Bud dormancy facilitates the survival of meristems under harsh environmental conditions.To elucidate how molecular responses to chilling accumulation controlling dormancy in peach buds,chromatin immunoprecipitation se...Bud dormancy facilitates the survival of meristems under harsh environmental conditions.To elucidate how molecular responses to chilling accumulation controlling dormancy in peach buds,chromatin immunoprecipitation sequencing to identify the H3K27me3 modifications and RNA sequencing of two peach cultivars with pronounced differences in chilling requirement were carried out,the results showed that genes associated with abscisic acid and gibberellic acid signal pathways play key roles in dormancy regulation.The results demonstrated that peach flower bud differentiation occurred continuously in both cultivars during chilling accumulation,which was correlated with the transcript abundance of key genes involved in phytohormone metabolism and flower bud development under adverse conditions.The more increased strength in high chillingrequirement cultivar along with the chilling accumulation at the genome-wide level.The function of the dormancy-associated MADS-box gene PpDAM6 was identified,which is involved in leaf bud break in peach and flower development in transgenic Nicotiana tabacum(NC89).In addition,PpDAM6 was positively regulated by PpCBF,and the genes of putative dormancy-related and associated with metabolic pathways were proposed.Taken together,these results constituted a theoretical basis for elucidating the regulation of peach bud dormancy transition.展开更多
Amaranthus retroflexus L. is a serious and widespread malignant weed in soybean fields in Heilongjiang Province. Exploring the dormancy characteristics of A. retroflexus L. seeds and the physiological response of its ...Amaranthus retroflexus L. is a serious and widespread malignant weed in soybean fields in Heilongjiang Province. Exploring the dormancy characteristics of A. retroflexus L. seeds and the physiological response of its seedlings to acifluorfen sodium can provide a basis for further researches on its resistance mechanism. Using newly harvested and stored A. retroflexus L. seeds for one year as experimental materials, the effects of different concentrations of HCl, NaOH, water temperature, gibberellic acid(GA) and polyethylene glycol(PEG) on the dormancy and germination of A. retroflexus L. seeds were studied. The sensitivity of A. retroflexus L.to acifluorfen sodium was determined using bioassay. The effects on leaf chlorophyll content and target enzyme activity were studied at a normal dosage of 360 g a.i. hm^(-2) and a doubling dosage of 720 g a.i. hm^(-2) of acifluorfen sodium. Newly harvested seeds exhibiting dormancy were soaked in water of various temperatures and in different concentrations of NaOH and HCl, which were ineffective in breaking the seed dormancy. GA could break seed dormancy, and the highest seed germination rate reached 93.33% when they were soaked at 3 000 mg·L^(-1) for 72 h and 4 000 mg·L^(-1) for 48 h. The drought stress was simulated with a 15%-25% polyethylene glycol solution, which had no significant effect on the seed germination rate. The GR_(50) value of acifluorfen sodium for A. retroflexus L. was 705.7 g a.i. hm^(-2), which was 1.96 times the recommended dose in the field. After the application of different doses of acifluorfen sodium, the chlorophyll content of A. retroflexus L. reached its minimum value 3 days after treatment(DAT), and then gradually increased. The activity of the target enzyme protoporphyrinogen oxidase(PPO) reached the highest value at 7 DAT under different dosages, and gradually returned to normal levels thereafter. Soaking with gibberellin was an effective method to break seed dormancy. A. retroflexus L. seeds had certain drought resistance during the germination process. A. retroflexus L. was not sensitive to acifluorfen sodium and acifluorfen sodium ether, and could not effectively inhibit the PPO activity, indicating that A. retroflexus L. had target resistance to acifluorfen sodium.展开更多
The crop seeds have been a staple food for humans,and seed yield is important for sustaining agriculture development and enhancing human adaptability to food risks.The phenomenon of pre-harvest sprouting(PHS),caused b...The crop seeds have been a staple food for humans,and seed yield is important for sustaining agriculture development and enhancing human adaptability to food risks.The phenomenon of pre-harvest sprouting(PHS),caused by seed dormancy deficiency,and the phenomenon of low seedling emergence caused by seed deep dormancy,will lead to a reduction in agricultural production.Therefore,it is particularly important to understand the regulation mechanisms of seed dormancy.There are many studies on the regulation of seed dormancy in rice,but there are few studies on the regulation of seed dormancy in other crops,and the research on its mechanism is not thorough enough.In this paper,we comprehensively summarize the regulation mechanisms of cereal seed dormancy,including rice,barley and wheat,discussing the integral mechanism of seed dormancy.This information should provide new insights for developing versatile cultivated lines to improve crop yield and economic benefits.展开更多
After harvest,potato tubers undergo an important period of dormancy,which significantly impacts potato quality and seed vigor.StSN2 has been reported as a key gene for maintaining tuber dormancy;in this study,we explo...After harvest,potato tubers undergo an important period of dormancy,which significantly impacts potato quality and seed vigor.StSN2 has been reported as a key gene for maintaining tuber dormancy;in this study,we explored the molecular mechanism by which StSN2 maintains dormancy.StBIN2 was first identified as a candidate protein that interacts with StSN2 by co-immunoprecipitation/mass spectrometry,and both qPCR and enzyme activity experiments showed that StSN2 can promote the StBIN2 expression and activity.In addition,the interaction between StSN2 and StBIN2 was verified by yeast two-hybrid,luciferase complementation experiments and co-immunoprecipitation.Bioinformatics analysis and site-directed mutagenesis confirmed the critical role of cysteine residues of StBIN2 in its binding to StSN2.Similar to that of StSN2,overexpression of StBIN2 extended the dormancy of potato tuber.Interaction between StSN2 and StBIN2 increased the activity of the StBIN2 enzyme,inhibited the expression of StBZR1,and suppressed BR signaling.On the contrary,this interaction promoted the expression of StSnRK2.2/2.3/2.4/2.6 and StABI5,key genes of ABA signaling,and the phosphorylation of StSnRK2.3,thereby promoting ABA signaling.Altogether,our results indicate that StSN2 interacts with StBIN2 through key cysteine residues and StBIN2 maintains tuber dormancy by affecting ABA and BR signaling.Findings of this research offer new insights into the molecular mechanism by which StSN2 maintains potato tuber dormancy through interaction with StSIN2 and provide guidance for potato improvement.展开更多
Green foxtail(Setaria viridis)is a notorious weed in corn fields in Heilongjiang Province.To investigate the best method to break the seed dormancy of green foxtail and its physiological response to topramezone,this s...Green foxtail(Setaria viridis)is a notorious weed in corn fields in Heilongjiang Province.To investigate the best method to break the seed dormancy of green foxtail and its physiological response to topramezone,this study selected newly harvested and one-year stored green foxtail seeds as research subjects.The seeds were treated with HCl,Na OH,gibberellic acid(GA),different water temperatures and polyethylene glycol(PEG)to study the seed dormancy and drought resistance of green foxtail.The results showed that newly harvested seeds exhibited dormancy,and treatments with HCl,NaOH and different water temperatures were unable to break the dormancy.Soaking the seeds in GA could overcome dormancy,but the seeds failed to germinate when exposed to 25%PEG concentration.When topramezone was applied at rates of 22.5 and 45.0 g a.i.·hm^(-2)at the 3-leaf and 5-leaf stages,respectively,the chlorophyll content reached the lowest value at 28 days after treatment(DAT).At the 7-leaf stage,the chlorophyll content reached the lowest value at 7 DAT.The activity of 4-hydroxyphenylpy-ruvate dioxygenase(HPPD)enzyme after topramezone application reached the maximum value at 7 DAT for different leaf ages,and the higher the leaf age,the higher the HPPD activity,which was an important factor contributing to the resistance of green foxtail to topramezone.展开更多
Primary dormancy of seeds of Korean pine(Pinus koraiensis Sieb.et Zucc.)after dispersal in the autumn and the induction of secondary dormancy the fi rst summer following seed dispersal limit the regeneration of mixed ...Primary dormancy of seeds of Korean pine(Pinus koraiensis Sieb.et Zucc.)after dispersal in the autumn and the induction of secondary dormancy the fi rst summer following seed dispersal limit the regeneration of mixed broadleaved Korean pine forests in Northeast China.This study was to determine how changes in the levels of abscisic acid(ABA)and gibberellic acid(GA)maintain primary and secondary dormancy of Korean pine seeds under germination conditions.We transferred seeds with one of fi ve primary dormancy states or three secondary dormancy states to germination conditions and measured changes in the levels of ABA,GA 1+3(GA 1 and GA 3)and GA 4+7(GA 4 and GA 7)in the seed coat,megagametophyte and embryo during incubation.Seed coat ABA levels in primary dormant seeds(PDS)and ABA levels in various parts of secondary dormant seeds(SDS)gradually declined during incubation but were still higher than in seeds for which dormancy was progressively released.GA 4+7 and GA 1+3 levels in embryos greatly decreased 35%and 24%,respectively,during incubation of SDS,and thus,the ratio of ABA to GA 4+7 in embryos and megagametophytes signifi cantly increased.The ratio of ABA to GA 1+3 in various parts of SDS increased slightly during incubation.In contrast,in seeds for which secondary dormancy was already released,GA 4+7 and GA 1+3 levels in the embryo,GA 4+7/ABA ratio in the embryo and seed coat,and the GA 1+3/ABA in the embryo and megagametophyte signifi cantly increased during incubation.There was no trend in the changes in the levels of ABA,GA 4+7 or GA 1+3 in embryos and megagametophytes of PDS or the levels of GA 4+7 or GA 1+3 in megagametophytes of SDS during incubation.The results suggest that high ABA levels in the seed coat maintain primary dormancy of Korean pine seeds.Maintenance of secondary dormancy involves a reduction of GA 4+7,GA 1+3,GA 4+7/ABA,and GA 1+3/ABA and the retention of high ABA levels.展开更多
Seasonal dormancy is an adaptive mechanism where plants suspend growth and become physiologically inactive to avoid extreme environmental conditions. Environmental factors like temperature, photoperiod, nutrients, and...Seasonal dormancy is an adaptive mechanism where plants suspend growth and become physiologically inactive to avoid extreme environmental conditions. Environmental factors like temperature, photoperiod, nutrients, and soil moisture control plant growth and development through various complex molecular mechanisms. Crown and seed dormancy of plants are mostly influenced by day length and temperature. Genes and physiological pathways triggered by these two factors along with genotype variability are some targets to manipulate seasonal dormancy. There is genetic variation in the depth and duration of seasonal dormancy. Therefore, their genetic manipulation is possible. Manipulations of summer and fall dormancy are relatively easier compared to winter dormancy because plants require protection of their apical meristem from freezing temperatures and limited water supply. Genetic factors that regulate seed dormancy may also have regulatory role for seasonal dormancy of the maternal plants. Limited genetic and genomic information are available for seasonal dormancy in herbaceous perennial species. Knowledge of genes controlling seasonal dormancy of eudicots, forest trees, and horticultural crops could be interpolated to explore possible dormancy mechanisms in perennial forages. This study reviews current knowledge of seasonal dormancy of herbaceous forages emphasizing the genetic and physiological context that would be valuable to breeders and plant biologists to expand the production season of perennial species by developing non-dormant and semi-dormant cultivars.展开更多
Pre-harvest sprouting(PHS)is a disadvantageous trait in cereal production worldwide,causing large economic losses each year.Its regulation mechanism is still unclear.We generated the Oryza sativa Viviparous1(OsVP1)mut...Pre-harvest sprouting(PHS)is a disadvantageous trait in cereal production worldwide,causing large economic losses each year.Its regulation mechanism is still unclear.We generated the Oryza sativa Viviparous1(OsVP1)mutant using gene editing technique,which shows increased PHS compared with that of the wild type Nipponbare.OsVP1 is localized mainly in the nucleus and expressed in various tissues and organs.Expression of Seed dormancy 4(Sdr4),a key gene controlling PHS,was sharply reduced in OsVP1 mutants.OsVP1 bound to the specific motif CACCTG in the promoter of Sdr4 and activated its expression in rice protoplasts.Overexpression of Sdr4 reduced the high seed germination rate of OsVP1 mutant cr-osvp1-1,showing that Sdr4 acts as a downstream target of OsVP1.Both OsVP1 and Sdr4 loss-of-function mutants were insensitive to exogenous ABA and employed the ABA signaling pathway in regulating seed dormancy.These findings shed light on the control of seed dormancy aimed at preventing PHS in rice.展开更多
Seed dormancy and germination characteristics are important factors determining plant reproductive success, and may be expected to have a major influence on plant distribution. In this study, we aimed to explore the c...Seed dormancy and germination characteristics are important factors determining plant reproductive success, and may be expected to have a major influence on plant distribution. In this study, we aimed to explore the characteristics of seed dormancy and germination in two endemic Rheum species(Rheum nobile and Rheum alexandrae) in the Himalaya-Hengduan Mountains. To determine the type of dormancy,fresh seeds of the two species(one population each) were incubated in light at 25/15 and 15/5℃, and then dry after-ripening(DAR) seeds were incubated on water agar substrate with or without GA_3. To determine the effect of temperature and light on germination, DAR seeds of the two species(two populations each) were incubated both in the light and in the dark at several temperatures, including constant and alternating temperatures. Base temperature(T_b) and thermal times for 50% germination(θ_(50)) were calculated. DAR released physiological dormancy(PD), increasing final germination at 15/5℃ and widening the range of germination temperatures from higher to lower, indicative of type 2 non-deep PD for the two Rheum species. Light had no significant effect on germination of seeds from the two species(two populations each). Seeds of the two species germinated significantly better(>80%) at medium temperatures(10-25℃) than at extreme low(5℃) or high(35℃) temperatures. Alternating temperatures(25/15 and 15/5℃) did not significantly increase the final germination of the two species either in the light and in the dark, but it promoted seed germination more quickly than corresponding constant temperatures in the light in both Rh. alexandrae populations, especially at 15/5℃. Germination in response to temperature was well described by the thermal-time model at suboptimal temperatures. The estimated Tbvalues were 1 and 0.9℃, respectively, in two Rh. nobile populations; 4 and 4.1℃,respectively, in two Rh. alexandrae populations; θ_(50)(thermal time) were 100 and 125℃d, respectively in two Rh. nobile populations; 76.92 and 83.33℃d, respectively in two Rh. alexandrae populations. The dormancy type, and germination responses to temperature and light condition does not explain why the two Rheum species are distributed in contrasting habitats. However, these findings reflect an advantageous germination strategy of these two Rheum species to adapt to the same alpine environments.展开更多
Plant dormancy is essential for perennial plant survival.Different genotypes of Prunus mume,including Eumume group and Apricot Mei group,undergo leaf senescence and dormancy at different times.In order to verify the c...Plant dormancy is essential for perennial plant survival.Different genotypes of Prunus mume,including Eumume group and Apricot Mei group,undergo leaf senescence and dormancy at different times.In order to verify the cold resistance of P.mume,freeze resistance evaluation was carried out.Our results showed that Apricot Mei group had a stronger freezing tolerance than Eumume group and that leaf senescence and dormancy of Apricot Mei group occurred at an earlier period before winter.Based on phenotypic data in response to seasonal climate change,the significant candidate regions were selected using GWAS.Furthermore,through KEGG pathway and qRT-PCR analyses,we found that the ethylene-related genes,including PmEIL(Pm002057)and PmERF(Pm004265),were significantly upregulated in‘Songchun’Mei(Apricot Mei group)and downregulated in‘Zaohua Lve’Mei(Eumume group).Ethylene-related genes expression models showed that ethylene may be indirectly involved in the induction of dormancy.The PmEIL and PmERF genes were the core genes of the ethylene signal transduction pathway and were regulated by the exogenous ACC or PZA compounds.For non-dormant or weekly dormant perennial plants,application of ACC was able to induce plant dormancy and thus enhance cold/freeze tolerance.Overall,the expression of the major ethylene genes played a significant role in dormancy induction and freezing tolerance in P.mume;accordingly,application of ACC and PZA compounds were an effective approach for enhancing cold/freeze of tolerance of woody plant.展开更多
In this study,two indica varieties with different dormancy characteristics [4 K58( II-32 B dormant),4 K59( II-32 B) ] and their F2 seeds( C178,C179) obtained through hybridization with sterile line( II-32 A) were used...In this study,two indica varieties with different dormancy characteristics [4 K58( II-32 B dormant),4 K59( II-32 B) ] and their F2 seeds( C178,C179) obtained through hybridization with sterile line( II-32 A) were used as materials. Different aged seeds( 0,3,6 and 9 d) of these four varieties were acquired by artificial accelerated aging method. Effects of artificial aging on malondialdehyde( MDA) content and catalase( CAT),ascorbate peroxidase( APX),peroxidase( POD) and superoxide dismutase( SOD) activity were investigated. The results showed that with the prolongation of aging time,MDA contents of these four rice varieties increased significantly,while the activity of antioxidant enzymes decreased dramatically. Besides,MDA contents and SOD,CAT and APX activity of the two inbred lines were significantly lower than those of the hybrid varieties. In addition,the activity of antioxidant enzymes in 4 K58 and C178 was significantly lower than that in 4 K59 and C179,respectively. This study indicated that artificial aging treatment significantly inhibited the activity of antioxidant system in seeds,improved membrane lipid peroxidation degree,and thus aggravated the deterioration of seeds. In addition,it also suggested that rice seeds with dormant property were more intolerant to storage.展开更多
Acer velutinum Boiss is a valuable tree species native to Iran, and its seeds possess physiological dormancy that hampers seedling production in the nursery for large-scale reforestation efforts. The aim of this study...Acer velutinum Boiss is a valuable tree species native to Iran, and its seeds possess physiological dormancy that hampers seedling production in the nursery for large-scale reforestation efforts. The aim of this study was to determine the optimal dormancy breaking treatments for A. velutinum seeds. We conducted a factorial experiment involving six seed lots collected along an elevation gradient from 300 to 1800 m at 300 m interval and four cold-moist stratification periods (0, 4, 8 and 16 weeks) at 4℃ and 70% relative humidity. The result shows that the germination of cold-moist stratified seeds was significantly (p < 0.0001) higher than the control for all seed lots. The highest germination capacity was recorded after 16 weeks of cold-moist stratification for all seed lots (68% 88% depending on the seed lot) except those collected from mid altitude sites (600 and 900 m) that germinated equally well (≥ 75%) after 4and 8-week of clod-moist stratification compared to the other seed lots. The mean germination time was significantly shorter (12 to 19 days, depending on the seed lot) for seeds stratified for 16 weeks than for untreated seeds. It can be concluded that: (1) cold-moist stratification for 16 weeks is the best pre-sowing treatment for breaking dormancy in A. velutinum seeds; and (2) seeds should be collected from mid altitude sites (600 and 900 m) to get more than 80% germination within 15 days, and these seed lots even required shorter cold-moist stratification period(eight weeks) than other seed lots.展开更多
Brassica napus cultivars have little or no primary dormancy;however,they are prone to sec on dary dorma ncy in ducti on.Secondary dormant seeds can produce volunteer plants,which can result in genetic contamination,re...Brassica napus cultivars have little or no primary dormancy;however,they are prone to sec on dary dorma ncy in ducti on.Secondary dormant seeds can produce volunteer plants,which can result in genetic contamination,reduced quality and biosafety issues.However,informati on regarding the molecular mecha nism un derlyi ng sec on dary dormancy is limited.The MOTHER OF FT AND TFL1(MFT)gene,which is evolutionarily conserved in the plant kingdom,acts in a complex gene network in the seed dormancy or germination processes.In this study,we identified four B.napus genes that share high homology with AtMFT,named as BnaMFT.Analyses of c/s-acting elements showed that BnaMFT promoters contain multiple seed-specific regulatory elements,and various stress-and hormone-responsive elements.Further experiments validated that BnaMFTs were specifically expressed during seed maturation and in the dry seed,with peaks at 35-42 days after pollination.BnaMFTs were not sufficient for primary dormancy;however,they were significantly enhanced by secondary dormancy induction with PEG6000 treatment.Moreover,BnaMFTtranscripts were elevated by treatment with abscisic acid(ABA),which is known to be accumulated duri ng sec on dary dorma ncy.These results collectively suggest that increased BnaMFT tra nscription levels are associated with sec on dary dorma ncy inducti on in an ABA-depe ndent mariner in B.napus.展开更多
Magnolia sinica is one of the most endangered Magnoliaceae species in China.Seed biology information concerning its long-term ex situ conservation and utilization is insufficient.This study investigated dormancy statu...Magnolia sinica is one of the most endangered Magnoliaceae species in China.Seed biology information concerning its long-term ex situ conservation and utilization is insufficient.This study investigated dormancy status,germination requirements and storage behavior of M.sinica.Freshly matured seeds germinated to ca.86.5%at 25/15℃but poorly at 30℃;GA3 and moist chilling promoted germination significantly at 20℃.Embryos grew at temperatures(alternating or constant)between 20℃and 25℃,but not at 5℃or 30℃.Our results indicate that M.sinica seeds possibly have non-deep simple mor-phophysiological dormancy(MPD).Seeds survived desiccation to 9.27%and 4.85%moisture content(MC)as well as a further 6-month storage at-20℃and in liquid nitrogen,including recovery in vitro as excised embryos.The established protocol ensured that at least 58%of seedlings were obtained after both cold storage and cryopreservation.These results indicate that both conventional seed banking and cryopreservation have potential as long-term ex situ conservation methods,although further optimized approaches are recommended for this critically endangered magnolia species.展开更多
The breaking of dormancy mediated by reac-tive nitrogen species(RNS)is related to the accumulation of reactive oxygen species(ROS)in germinating embryos but the underlying mechanism is unclear.The objectives of this s...The breaking of dormancy mediated by reac-tive nitrogen species(RNS)is related to the accumulation of reactive oxygen species(ROS)in germinating embryos but the underlying mechanism is unclear.The objectives of this study were:(1)to explore the relationship between RNS-mediated dormancy release and ROS accumulation in germinating embryos of Sorbus pohuashanensis;and,(2)to investigate the relationships among germination time,ROS metabolism,and endogenous hormone synthesis.We studied the effects of exogenous nitric oxide(NO)donor sodium nitroprusside(SNP),the NO scavenger(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide(PTIO),abscisic acid(ABA),the exogenous ethylene donor ethrel,and the ethylene receptor inhibitor 2,5-norbornadien(NBD)on embryo germination and seedling growth.Embryos were released from dormancy by pretreatment with NO or ethylene, which was related to increased ethylene biosyn-thesis and decreased ABA levels. Breaking of dormancy by SNP was related to increased levels of ethylene, hydrogen peroxide, and glutathione, increased activities of superoxide dismutase and glutathione peroxidase, and decreased levels of ABA, superoxide anions, and malondialdehyde. These effects of nitric oxide were especially significant in seedling hypocotyls and radicles. These results demonstrate that NO can break S. pohuashanensis embryo dormancy by induc-ing ethylene biosynthesis, and that this signalling pathway is closely related to ROS accumulation and the antioxidant defence response.展开更多
Over the past few decades, major strides have advanced the techniques for early detection and treatment of cancer. However, metastatic tumor growth still accounts for the majority of cancer-related deaths worldwide. I...Over the past few decades, major strides have advanced the techniques for early detection and treatment of cancer. However, metastatic tumor growth still accounts for the majority of cancer-related deaths worldwide. In fact, breast cancers are notorious for relapsing years or decades after the initial clinical treatment, and this relapse can vary according to the type of breast cancer. In estrogen receptor-positive breast cancers, late tumor relapses frequently occur whereas relapses in estrogen receptor-negative cancers or triple negative tumors arise early resulting in a higher mortality risk. One of the main causes of metastasis is tumor dormancy in which cancer cells remain concealed, asymptomatic, and untraceable over a prolonged period of time. Under certain conditions, dormant cells can re-enter into the cell cycle and resume proliferation leading to recurrence. However, the molecular and cellular regulators underlying this transition remain poorly understood. To date, three mechanisms have been identified to trigger tumor dormancy including cellular, angiogenic, and immunologic dormancies. In addition, recent studies have suggested that DNA repair mechanisms may contribute to the survival of dormant cancer cells. In this article, we summarize the recent experimental and clinical evidence governing cancer dormancy. In addition, we will discuss the role of DNA repair mechanisms in promoting the survival of dormant cells. This information provides mechanistic insight to explain why recurrence occurs, and strategies that may enhance therapeutic approaches to prevent disease recurrence.展开更多
Fig (Ficus carica L.) is a deciduous species well adapted to Mediterranean conditions but its chilling requirement is still not well understood. The present study examines the pattern of bud-break in seven fig cultiva...Fig (Ficus carica L.) is a deciduous species well adapted to Mediterranean conditions but its chilling requirement is still not well understood. The present study examines the pattern of bud-break in seven fig cultivars over two years under Moroccan conditions. Evaluation of dormancy behavior was made using a biological test known as “single node cuttings” carried out under controlled conditions. The responses of cultivars from Morocco, Italy, Spain and France were assessed. The period from full leaf fall to bud-break was characterized by a small variation (10 - 20 days) which did not appear to reflect the origin of the cultivars. Steady-sates were at high level in the middle of December or in January depending on the year. During the cold period, MTB didn’t exceed 200 days for “Borjassate noire”, “Ournakssi” and “Kadota” and varied from 100 to 128 days for the other cultivars. Therefore, dormancy was not deep and its period was short. Forcing bud during the coldest period allowed to a bud break but it didn’t exceed 10% and dormancy wasn’t complete. Missing bud break wasn’t observed and the geographic origin of examined cultivars didn’t seem to determine the length, and the deepness of bud dormancy. Bud-break occurred within a month of last leaf fall in the cultivars, indicating that they were all suited to commercial production in Morocco. Apparently, bud-break is more reliable in fig than it is in other Rosaceous species in this environment.展开更多
Switchgrass is a prominent bioenergy crop. Like most perennial warm season species, switchgrass undergoes growth suspension in winter as a surviving strategy in temperate climates to protect their meristems from cold ...Switchgrass is a prominent bioenergy crop. Like most perennial warm season species, switchgrass undergoes growth suspension in winter as a surviving strategy in temperate climates to protect their meristems from cold injuries and dehydration, while storage organs below ground drive spring regrowth when conditions become favourable. In this paper, we describe a reliable phenotyping method for winter dormancy in switchgrass using various traits including regrowth height after clipping in early fall (FRH), senescence percentage, date of spring regrowth (SRD), and flowering date (FD). FRH and senescence percentage appear to be reliable indicators of the onset of winter dormancy, whereby accessions that initiated dormancy early have a low FRH and a high senescence percentage. Even though it is difficult to have an exact assessment of the duration of dormancy because it is hard to determine with precision the date of growth suspension, SRD can be used as a surrogate indicator of the duration. Flowering date showed low correlations with all the traits and biomass yield suggesting that it may not be a reliable indicator for winter dormancy in switchgrass. Combining the variables FRH, senescence, and SRD in a selection index may provide a reliable tool to phenotype winter dormancy in switchgrass. The strong correlation of these variables with biomass yield makes them useful candidates for the manipulation of the duration of dormancy to increase the growing season and consequently improving biomass production. In southern regions with mild winters, it might be possible through intense selection to develop germplasm with much reduced dormancy or even non-dormant switchgrass germplasm.展开更多
The Fabaceae(legume family) is one of the largest families of plants with a worldwide distribution and a major role in agriculture and in agroforestry.A hard seed coat impermeable to water is a typical feature of seve...The Fabaceae(legume family) is one of the largest families of plants with a worldwide distribution and a major role in agriculture and in agroforestry.A hard seed coat impermeable to water is a typical feature of several species.Physical dormancy delays and reduces germination so that mechanical,physical and chemical scarification methods have been classically used to break seed dormancy of many species.We evaluate the effectiveness of a methodology to scarify seeds of several woody Fabaceae of ecological and economical importance,including Robinia pseudoacacia and Acacia dealbata and the shrubs Cytisus scoparius,C.multiflorus and Ulex europaeus.We describe the optimized use of a handheld rotary tool(HRT),and compare its effectiveness with other scarification methods reported to break dormancy such as boiling or dry heating.Total germination and/or speed of germination were enhanced after the application of the HRT,with germination percentages significantly higher than those achieved by other methods of scarification.Based on a thorough literature review,a mode of action for the HRT is suggested which could operate by breaking the physical and physiological dormancy of treated seeds through thecombined action of coat abrasion and moderate temperatures.Considering these results,we recommend the application of this rapid,effective,low-cost and highly reproducible HRT method to break seed dormancy and enhance germination of these species and others with similar dormancy constraints.展开更多
Elucidating the regulatory mechanisms of environmental factors on seed dormancy and germination will provide guidance for tree regeneration.Toward understanding the coupled effect of light and temperature on dormancy ...Elucidating the regulatory mechanisms of environmental factors on seed dormancy and germination will provide guidance for tree regeneration.Toward understanding the coupled effect of light and temperature on dormancy release and germination of Pinus koraiensis seeds,we set up three light conditions(L200:200μmol m^(-2) s^(-1),L20:20μmol m^(-2) s^(-1),L0:0μm^(-2) s^(-1))and four storage temperatures[T-5:-5°C(50 days),T5:-5°C(50 days)+5°C(50 days),T25:-5°C(50 days)+5°C(50 days)+25°C(50 days),T15:-5°C(50 days)+5°C(50 days)+25°C(50 days)+15°C(50 days)]using imbibed seeds,then quantified phytohormones gibberellic acid(GA_(3))and abscisic acid(ABA)during the stratification.Germination percentage(G_(P)),mean germination time(T_(M)),and germination value(G_(V))under 25/15°C temperature and the three light conditions were then determined.Phytohormone levels and germination performances were significantly affected by light and temperature.No consistent trend was found between the phytohormone levels and G_(P) caused by light levels.Under the three light conditions,ABA concentrations in the embryo and endosperm decreased as storage temperature shifted from T-5 to T25 and increased from T25 to T15;GA_(3) decreased in nearly all four storage temperatures.G_(P) reached 40–60%in T25 storage without light irradiance.In the three light conditions,G_(P) and G_(V) were higher at T5 and T25 than at T-5 and T15;so T5 and T25 are considered as optimum storage temperatures for dormancy release and germination.At optimum temperatures,light(L200,L20)significantly increased the G_(P) and G_(V) compared with the dark(L0).At L200 and L20,significant negative correlations between G_(V) and the ABA concentrations and positive correlations between G_(V) and GA/ABA in the seed embryo were found.Temperature played a more important role in primary dormancy release and germination;light was unnecessary for primary dormancy release.Light facilitated seed germination at optimum temperatures.The dormancy release and germination of P.koraiensis seeds were controlled by a decrease in ABA concentrations or an increase in GA/ABA induced by temperature variations.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.32001996)Central Publicinterest Scientific Institution Basal Research Fund(Grant No.Y2022QC23)+2 种基金Agricultural Science and Technology Innovation Program(Grant No.CAAS-ASTIP-2021-ZFRI-01)the Crop Germplasm Resources Conservation Project(Grant No.2016NWB041)the Science and Technology Major Project of Yunnan(Gene mining and breeding of peach at highaltitude and low-latitude regions)。
文摘Bud dormancy facilitates the survival of meristems under harsh environmental conditions.To elucidate how molecular responses to chilling accumulation controlling dormancy in peach buds,chromatin immunoprecipitation sequencing to identify the H3K27me3 modifications and RNA sequencing of two peach cultivars with pronounced differences in chilling requirement were carried out,the results showed that genes associated with abscisic acid and gibberellic acid signal pathways play key roles in dormancy regulation.The results demonstrated that peach flower bud differentiation occurred continuously in both cultivars during chilling accumulation,which was correlated with the transcript abundance of key genes involved in phytohormone metabolism and flower bud development under adverse conditions.The more increased strength in high chillingrequirement cultivar along with the chilling accumulation at the genome-wide level.The function of the dormancy-associated MADS-box gene PpDAM6 was identified,which is involved in leaf bud break in peach and flower development in transgenic Nicotiana tabacum(NC89).In addition,PpDAM6 was positively regulated by PpCBF,and the genes of putative dormancy-related and associated with metabolic pathways were proposed.Taken together,these results constituted a theoretical basis for elucidating the regulation of peach bud dormancy transition.
基金Supported by the National Major Special Project for the Cultivation of New Genetically Modified Biological Varieties(Topic ZX08011-003)。
文摘Amaranthus retroflexus L. is a serious and widespread malignant weed in soybean fields in Heilongjiang Province. Exploring the dormancy characteristics of A. retroflexus L. seeds and the physiological response of its seedlings to acifluorfen sodium can provide a basis for further researches on its resistance mechanism. Using newly harvested and stored A. retroflexus L. seeds for one year as experimental materials, the effects of different concentrations of HCl, NaOH, water temperature, gibberellic acid(GA) and polyethylene glycol(PEG) on the dormancy and germination of A. retroflexus L. seeds were studied. The sensitivity of A. retroflexus L.to acifluorfen sodium was determined using bioassay. The effects on leaf chlorophyll content and target enzyme activity were studied at a normal dosage of 360 g a.i. hm^(-2) and a doubling dosage of 720 g a.i. hm^(-2) of acifluorfen sodium. Newly harvested seeds exhibiting dormancy were soaked in water of various temperatures and in different concentrations of NaOH and HCl, which were ineffective in breaking the seed dormancy. GA could break seed dormancy, and the highest seed germination rate reached 93.33% when they were soaked at 3 000 mg·L^(-1) for 72 h and 4 000 mg·L^(-1) for 48 h. The drought stress was simulated with a 15%-25% polyethylene glycol solution, which had no significant effect on the seed germination rate. The GR_(50) value of acifluorfen sodium for A. retroflexus L. was 705.7 g a.i. hm^(-2), which was 1.96 times the recommended dose in the field. After the application of different doses of acifluorfen sodium, the chlorophyll content of A. retroflexus L. reached its minimum value 3 days after treatment(DAT), and then gradually increased. The activity of the target enzyme protoporphyrinogen oxidase(PPO) reached the highest value at 7 DAT under different dosages, and gradually returned to normal levels thereafter. Soaking with gibberellin was an effective method to break seed dormancy. A. retroflexus L. seeds had certain drought resistance during the germination process. A. retroflexus L. was not sensitive to acifluorfen sodium and acifluorfen sodium ether, and could not effectively inhibit the PPO activity, indicating that A. retroflexus L. had target resistance to acifluorfen sodium.
基金funded by the National Natural Science Foundation of China(Grant No.32170562).
文摘The crop seeds have been a staple food for humans,and seed yield is important for sustaining agriculture development and enhancing human adaptability to food risks.The phenomenon of pre-harvest sprouting(PHS),caused by seed dormancy deficiency,and the phenomenon of low seedling emergence caused by seed deep dormancy,will lead to a reduction in agricultural production.Therefore,it is particularly important to understand the regulation mechanisms of seed dormancy.There are many studies on the regulation of seed dormancy in rice,but there are few studies on the regulation of seed dormancy in other crops,and the research on its mechanism is not thorough enough.In this paper,we comprehensively summarize the regulation mechanisms of cereal seed dormancy,including rice,barley and wheat,discussing the integral mechanism of seed dormancy.This information should provide new insights for developing versatile cultivated lines to improve crop yield and economic benefits.
基金This work was supported by the Innovation Team Project no.sccxtd-2023-09 of the Modern Agricultural Industrious Technology System of Sichuan Provincethe Biological Breeding Project no.SKL-ZY202203 of the State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China.We thank A&L Scientific Editing(www.alpublish.com)for the linguistic assistance during the preparation of this manuscript.
文摘After harvest,potato tubers undergo an important period of dormancy,which significantly impacts potato quality and seed vigor.StSN2 has been reported as a key gene for maintaining tuber dormancy;in this study,we explored the molecular mechanism by which StSN2 maintains dormancy.StBIN2 was first identified as a candidate protein that interacts with StSN2 by co-immunoprecipitation/mass spectrometry,and both qPCR and enzyme activity experiments showed that StSN2 can promote the StBIN2 expression and activity.In addition,the interaction between StSN2 and StBIN2 was verified by yeast two-hybrid,luciferase complementation experiments and co-immunoprecipitation.Bioinformatics analysis and site-directed mutagenesis confirmed the critical role of cysteine residues of StBIN2 in its binding to StSN2.Similar to that of StSN2,overexpression of StBIN2 extended the dormancy of potato tuber.Interaction between StSN2 and StBIN2 increased the activity of the StBIN2 enzyme,inhibited the expression of StBZR1,and suppressed BR signaling.On the contrary,this interaction promoted the expression of StSnRK2.2/2.3/2.4/2.6 and StABI5,key genes of ABA signaling,and the phosphorylation of StSnRK2.3,thereby promoting ABA signaling.Altogether,our results indicate that StSN2 interacts with StBIN2 through key cysteine residues and StBIN2 maintains tuber dormancy by affecting ABA and BR signaling.Findings of this research offer new insights into the molecular mechanism by which StSN2 maintains potato tuber dormancy through interaction with StSIN2 and provide guidance for potato improvement.
基金Supported by the National Major Special Project for the Cultivation of New Genetically Modified Biological Varieties(2018)(Topic ZX08011-003)。
文摘Green foxtail(Setaria viridis)is a notorious weed in corn fields in Heilongjiang Province.To investigate the best method to break the seed dormancy of green foxtail and its physiological response to topramezone,this study selected newly harvested and one-year stored green foxtail seeds as research subjects.The seeds were treated with HCl,Na OH,gibberellic acid(GA),different water temperatures and polyethylene glycol(PEG)to study the seed dormancy and drought resistance of green foxtail.The results showed that newly harvested seeds exhibited dormancy,and treatments with HCl,NaOH and different water temperatures were unable to break the dormancy.Soaking the seeds in GA could overcome dormancy,but the seeds failed to germinate when exposed to 25%PEG concentration.When topramezone was applied at rates of 22.5 and 45.0 g a.i.·hm^(-2)at the 3-leaf and 5-leaf stages,respectively,the chlorophyll content reached the lowest value at 28 days after treatment(DAT).At the 7-leaf stage,the chlorophyll content reached the lowest value at 7 DAT.The activity of 4-hydroxyphenylpy-ruvate dioxygenase(HPPD)enzyme after topramezone application reached the maximum value at 7 DAT for different leaf ages,and the higher the leaf age,the higher the HPPD activity,which was an important factor contributing to the resistance of green foxtail to topramezone.
基金We thank Kai Yang and Lizhong Yu and Xiao Zheng and Tao Sun for valuable discussion and suggestions about this study.We also thank Hongjun Xu,Jingpu Zhang,Weiwei Zhang and Shuang Xu for fi eld support and technical assistance.
文摘Primary dormancy of seeds of Korean pine(Pinus koraiensis Sieb.et Zucc.)after dispersal in the autumn and the induction of secondary dormancy the fi rst summer following seed dispersal limit the regeneration of mixed broadleaved Korean pine forests in Northeast China.This study was to determine how changes in the levels of abscisic acid(ABA)and gibberellic acid(GA)maintain primary and secondary dormancy of Korean pine seeds under germination conditions.We transferred seeds with one of fi ve primary dormancy states or three secondary dormancy states to germination conditions and measured changes in the levels of ABA,GA 1+3(GA 1 and GA 3)and GA 4+7(GA 4 and GA 7)in the seed coat,megagametophyte and embryo during incubation.Seed coat ABA levels in primary dormant seeds(PDS)and ABA levels in various parts of secondary dormant seeds(SDS)gradually declined during incubation but were still higher than in seeds for which dormancy was progressively released.GA 4+7 and GA 1+3 levels in embryos greatly decreased 35%and 24%,respectively,during incubation of SDS,and thus,the ratio of ABA to GA 4+7 in embryos and megagametophytes signifi cantly increased.The ratio of ABA to GA 1+3 in various parts of SDS increased slightly during incubation.In contrast,in seeds for which secondary dormancy was already released,GA 4+7 and GA 1+3 levels in the embryo,GA 4+7/ABA ratio in the embryo and seed coat,and the GA 1+3/ABA in the embryo and megagametophyte signifi cantly increased during incubation.There was no trend in the changes in the levels of ABA,GA 4+7 or GA 1+3 in embryos and megagametophytes of PDS or the levels of GA 4+7 or GA 1+3 in megagametophytes of SDS during incubation.The results suggest that high ABA levels in the seed coat maintain primary dormancy of Korean pine seeds.Maintenance of secondary dormancy involves a reduction of GA 4+7,GA 1+3,GA 4+7/ABA,and GA 1+3/ABA and the retention of high ABA levels.
文摘Seasonal dormancy is an adaptive mechanism where plants suspend growth and become physiologically inactive to avoid extreme environmental conditions. Environmental factors like temperature, photoperiod, nutrients, and soil moisture control plant growth and development through various complex molecular mechanisms. Crown and seed dormancy of plants are mostly influenced by day length and temperature. Genes and physiological pathways triggered by these two factors along with genotype variability are some targets to manipulate seasonal dormancy. There is genetic variation in the depth and duration of seasonal dormancy. Therefore, their genetic manipulation is possible. Manipulations of summer and fall dormancy are relatively easier compared to winter dormancy because plants require protection of their apical meristem from freezing temperatures and limited water supply. Genetic factors that regulate seed dormancy may also have regulatory role for seasonal dormancy of the maternal plants. Limited genetic and genomic information are available for seasonal dormancy in herbaceous perennial species. Knowledge of genes controlling seasonal dormancy of eudicots, forest trees, and horticultural crops could be interpolated to explore possible dormancy mechanisms in perennial forages. This study reviews current knowledge of seasonal dormancy of herbaceous forages emphasizing the genetic and physiological context that would be valuable to breeders and plant biologists to expand the production season of perennial species by developing non-dormant and semi-dormant cultivars.
基金supported by grants from the National Major Science and Technology Program on New GMO Organism Variety Breeding(2016ZX08001-001)Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(CAAS)。
文摘Pre-harvest sprouting(PHS)is a disadvantageous trait in cereal production worldwide,causing large economic losses each year.Its regulation mechanism is still unclear.We generated the Oryza sativa Viviparous1(OsVP1)mutant using gene editing technique,which shows increased PHS compared with that of the wild type Nipponbare.OsVP1 is localized mainly in the nucleus and expressed in various tissues and organs.Expression of Seed dormancy 4(Sdr4),a key gene controlling PHS,was sharply reduced in OsVP1 mutants.OsVP1 bound to the specific motif CACCTG in the promoter of Sdr4 and activated its expression in rice protoplasts.Overexpression of Sdr4 reduced the high seed germination rate of OsVP1 mutant cr-osvp1-1,showing that Sdr4 acts as a downstream target of OsVP1.Both OsVP1 and Sdr4 loss-of-function mutants were insensitive to exogenous ABA and employed the ABA signaling pathway in regulating seed dormancy.These findings shed light on the control of seed dormancy aimed at preventing PHS in rice.
基金supported by National Key Research and Development Program of China (2017YFC0505201)NSFC (grant 31670206 to Z.-M. L. and 31570228 to B. S.),major Program of NSFC (grant 31590823 to H. S.)+1 种基金the Orientation Training Programme for Postdoctoral Fellows from Yunnan Province to D.-L. P.the Young Academic and Technical Leader Raising Foundation of Yunnan Province to B. S.
文摘Seed dormancy and germination characteristics are important factors determining plant reproductive success, and may be expected to have a major influence on plant distribution. In this study, we aimed to explore the characteristics of seed dormancy and germination in two endemic Rheum species(Rheum nobile and Rheum alexandrae) in the Himalaya-Hengduan Mountains. To determine the type of dormancy,fresh seeds of the two species(one population each) were incubated in light at 25/15 and 15/5℃, and then dry after-ripening(DAR) seeds were incubated on water agar substrate with or without GA_3. To determine the effect of temperature and light on germination, DAR seeds of the two species(two populations each) were incubated both in the light and in the dark at several temperatures, including constant and alternating temperatures. Base temperature(T_b) and thermal times for 50% germination(θ_(50)) were calculated. DAR released physiological dormancy(PD), increasing final germination at 15/5℃ and widening the range of germination temperatures from higher to lower, indicative of type 2 non-deep PD for the two Rheum species. Light had no significant effect on germination of seeds from the two species(two populations each). Seeds of the two species germinated significantly better(>80%) at medium temperatures(10-25℃) than at extreme low(5℃) or high(35℃) temperatures. Alternating temperatures(25/15 and 15/5℃) did not significantly increase the final germination of the two species either in the light and in the dark, but it promoted seed germination more quickly than corresponding constant temperatures in the light in both Rh. alexandrae populations, especially at 15/5℃. Germination in response to temperature was well described by the thermal-time model at suboptimal temperatures. The estimated Tbvalues were 1 and 0.9℃, respectively, in two Rh. nobile populations; 4 and 4.1℃,respectively, in two Rh. alexandrae populations; θ_(50)(thermal time) were 100 and 125℃d, respectively in two Rh. nobile populations; 76.92 and 83.33℃d, respectively in two Rh. alexandrae populations. The dormancy type, and germination responses to temperature and light condition does not explain why the two Rheum species are distributed in contrasting habitats. However, these findings reflect an advantageous germination strategy of these two Rheum species to adapt to the same alpine environments.
基金The research was supported by the National Key Research and Development Programof China(Grant No.2019YFD1001500)the National Natural Science Foundation of China(Grant No.31800595)Special Fund for Beijing Common Construction Project.
文摘Plant dormancy is essential for perennial plant survival.Different genotypes of Prunus mume,including Eumume group and Apricot Mei group,undergo leaf senescence and dormancy at different times.In order to verify the cold resistance of P.mume,freeze resistance evaluation was carried out.Our results showed that Apricot Mei group had a stronger freezing tolerance than Eumume group and that leaf senescence and dormancy of Apricot Mei group occurred at an earlier period before winter.Based on phenotypic data in response to seasonal climate change,the significant candidate regions were selected using GWAS.Furthermore,through KEGG pathway and qRT-PCR analyses,we found that the ethylene-related genes,including PmEIL(Pm002057)and PmERF(Pm004265),were significantly upregulated in‘Songchun’Mei(Apricot Mei group)and downregulated in‘Zaohua Lve’Mei(Eumume group).Ethylene-related genes expression models showed that ethylene may be indirectly involved in the induction of dormancy.The PmEIL and PmERF genes were the core genes of the ethylene signal transduction pathway and were regulated by the exogenous ACC or PZA compounds.For non-dormant or weekly dormant perennial plants,application of ACC was able to induce plant dormancy and thus enhance cold/freeze tolerance.Overall,the expression of the major ethylene genes played a significant role in dormancy induction and freezing tolerance in P.mume;accordingly,application of ACC and PZA compounds were an effective approach for enhancing cold/freeze of tolerance of woody plant.
基金Supported by National Key Research and Development Project(2018YFD0101000)
文摘In this study,two indica varieties with different dormancy characteristics [4 K58( II-32 B dormant),4 K59( II-32 B) ] and their F2 seeds( C178,C179) obtained through hybridization with sterile line( II-32 A) were used as materials. Different aged seeds( 0,3,6 and 9 d) of these four varieties were acquired by artificial accelerated aging method. Effects of artificial aging on malondialdehyde( MDA) content and catalase( CAT),ascorbate peroxidase( APX),peroxidase( POD) and superoxide dismutase( SOD) activity were investigated. The results showed that with the prolongation of aging time,MDA contents of these four rice varieties increased significantly,while the activity of antioxidant enzymes decreased dramatically. Besides,MDA contents and SOD,CAT and APX activity of the two inbred lines were significantly lower than those of the hybrid varieties. In addition,the activity of antioxidant enzymes in 4 K58 and C178 was significantly lower than that in 4 K59 and C179,respectively. This study indicated that artificial aging treatment significantly inhibited the activity of antioxidant system in seeds,improved membrane lipid peroxidation degree,and thus aggravated the deterioration of seeds. In addition,it also suggested that rice seeds with dormant property were more intolerant to storage.
基金the Gorgan University of Agricultural Sciences and Natural Resources for supporting this research
文摘Acer velutinum Boiss is a valuable tree species native to Iran, and its seeds possess physiological dormancy that hampers seedling production in the nursery for large-scale reforestation efforts. The aim of this study was to determine the optimal dormancy breaking treatments for A. velutinum seeds. We conducted a factorial experiment involving six seed lots collected along an elevation gradient from 300 to 1800 m at 300 m interval and four cold-moist stratification periods (0, 4, 8 and 16 weeks) at 4℃ and 70% relative humidity. The result shows that the germination of cold-moist stratified seeds was significantly (p < 0.0001) higher than the control for all seed lots. The highest germination capacity was recorded after 16 weeks of cold-moist stratification for all seed lots (68% 88% depending on the seed lot) except those collected from mid altitude sites (600 and 900 m) that germinated equally well (≥ 75%) after 4and 8-week of clod-moist stratification compared to the other seed lots. The mean germination time was significantly shorter (12 to 19 days, depending on the seed lot) for seeds stratified for 16 weeks than for untreated seeds. It can be concluded that: (1) cold-moist stratification for 16 weeks is the best pre-sowing treatment for breaking dormancy in A. velutinum seeds; and (2) seeds should be collected from mid altitude sites (600 and 900 m) to get more than 80% germination within 15 days, and these seed lots even required shorter cold-moist stratification period(eight weeks) than other seed lots.
基金This work was funded by the National Natural Science Foundation of China(31470572 and 31701514)and the Qing Lan Project of Jiangsu Province,China(2016).
文摘Brassica napus cultivars have little or no primary dormancy;however,they are prone to sec on dary dorma ncy in ducti on.Secondary dormant seeds can produce volunteer plants,which can result in genetic contamination,reduced quality and biosafety issues.However,informati on regarding the molecular mecha nism un derlyi ng sec on dary dormancy is limited.The MOTHER OF FT AND TFL1(MFT)gene,which is evolutionarily conserved in the plant kingdom,acts in a complex gene network in the seed dormancy or germination processes.In this study,we identified four B.napus genes that share high homology with AtMFT,named as BnaMFT.Analyses of c/s-acting elements showed that BnaMFT promoters contain multiple seed-specific regulatory elements,and various stress-and hormone-responsive elements.Further experiments validated that BnaMFTs were specifically expressed during seed maturation and in the dry seed,with peaks at 35-42 days after pollination.BnaMFTs were not sufficient for primary dormancy;however,they were significantly enhanced by secondary dormancy induction with PEG6000 treatment.Moreover,BnaMFTtranscripts were elevated by treatment with abscisic acid(ABA),which is known to be accumulated duri ng sec on dary dorma ncy.These results collectively suggest that increased BnaMFT tra nscription levels are associated with sec on dary dorma ncy inducti on in an ABA-depe ndent mariner in B.napus.
文摘Magnolia sinica is one of the most endangered Magnoliaceae species in China.Seed biology information concerning its long-term ex situ conservation and utilization is insufficient.This study investigated dormancy status,germination requirements and storage behavior of M.sinica.Freshly matured seeds germinated to ca.86.5%at 25/15℃but poorly at 30℃;GA3 and moist chilling promoted germination significantly at 20℃.Embryos grew at temperatures(alternating or constant)between 20℃and 25℃,but not at 5℃or 30℃.Our results indicate that M.sinica seeds possibly have non-deep simple mor-phophysiological dormancy(MPD).Seeds survived desiccation to 9.27%and 4.85%moisture content(MC)as well as a further 6-month storage at-20℃and in liquid nitrogen,including recovery in vitro as excised embryos.The established protocol ensured that at least 58%of seedlings were obtained after both cold storage and cryopreservation.These results indicate that both conventional seed banking and cryopreservation have potential as long-term ex situ conservation methods,although further optimized approaches are recommended for this critically endangered magnolia species.
基金provided by National Natural Science Foundation of China(No.32071757)National Natural Science Foundation of Heilongjiang Province of China(C201407).
文摘The breaking of dormancy mediated by reac-tive nitrogen species(RNS)is related to the accumulation of reactive oxygen species(ROS)in germinating embryos but the underlying mechanism is unclear.The objectives of this study were:(1)to explore the relationship between RNS-mediated dormancy release and ROS accumulation in germinating embryos of Sorbus pohuashanensis;and,(2)to investigate the relationships among germination time,ROS metabolism,and endogenous hormone synthesis.We studied the effects of exogenous nitric oxide(NO)donor sodium nitroprusside(SNP),the NO scavenger(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide(PTIO),abscisic acid(ABA),the exogenous ethylene donor ethrel,and the ethylene receptor inhibitor 2,5-norbornadien(NBD)on embryo germination and seedling growth.Embryos were released from dormancy by pretreatment with NO or ethylene, which was related to increased ethylene biosyn-thesis and decreased ABA levels. Breaking of dormancy by SNP was related to increased levels of ethylene, hydrogen peroxide, and glutathione, increased activities of superoxide dismutase and glutathione peroxidase, and decreased levels of ABA, superoxide anions, and malondialdehyde. These effects of nitric oxide were especially significant in seedling hypocotyls and radicles. These results demonstrate that NO can break S. pohuashanensis embryo dormancy by induc-ing ethylene biosynthesis, and that this signalling pathway is closely related to ROS accumulation and the antioxidant defence response.
基金Supported by The DOD Innovator and Scholar Concept Award,No.W81XWH-12-1-0372
文摘Over the past few decades, major strides have advanced the techniques for early detection and treatment of cancer. However, metastatic tumor growth still accounts for the majority of cancer-related deaths worldwide. In fact, breast cancers are notorious for relapsing years or decades after the initial clinical treatment, and this relapse can vary according to the type of breast cancer. In estrogen receptor-positive breast cancers, late tumor relapses frequently occur whereas relapses in estrogen receptor-negative cancers or triple negative tumors arise early resulting in a higher mortality risk. One of the main causes of metastasis is tumor dormancy in which cancer cells remain concealed, asymptomatic, and untraceable over a prolonged period of time. Under certain conditions, dormant cells can re-enter into the cell cycle and resume proliferation leading to recurrence. However, the molecular and cellular regulators underlying this transition remain poorly understood. To date, three mechanisms have been identified to trigger tumor dormancy including cellular, angiogenic, and immunologic dormancies. In addition, recent studies have suggested that DNA repair mechanisms may contribute to the survival of dormant cancer cells. In this article, we summarize the recent experimental and clinical evidence governing cancer dormancy. In addition, we will discuss the role of DNA repair mechanisms in promoting the survival of dormant cells. This information provides mechanistic insight to explain why recurrence occurs, and strategies that may enhance therapeutic approaches to prevent disease recurrence.
文摘Fig (Ficus carica L.) is a deciduous species well adapted to Mediterranean conditions but its chilling requirement is still not well understood. The present study examines the pattern of bud-break in seven fig cultivars over two years under Moroccan conditions. Evaluation of dormancy behavior was made using a biological test known as “single node cuttings” carried out under controlled conditions. The responses of cultivars from Morocco, Italy, Spain and France were assessed. The period from full leaf fall to bud-break was characterized by a small variation (10 - 20 days) which did not appear to reflect the origin of the cultivars. Steady-sates were at high level in the middle of December or in January depending on the year. During the cold period, MTB didn’t exceed 200 days for “Borjassate noire”, “Ournakssi” and “Kadota” and varied from 100 to 128 days for the other cultivars. Therefore, dormancy was not deep and its period was short. Forcing bud during the coldest period allowed to a bud break but it didn’t exceed 10% and dormancy wasn’t complete. Missing bud break wasn’t observed and the geographic origin of examined cultivars didn’t seem to determine the length, and the deepness of bud dormancy. Bud-break occurred within a month of last leaf fall in the cultivars, indicating that they were all suited to commercial production in Morocco. Apparently, bud-break is more reliable in fig than it is in other Rosaceous species in this environment.
文摘Switchgrass is a prominent bioenergy crop. Like most perennial warm season species, switchgrass undergoes growth suspension in winter as a surviving strategy in temperate climates to protect their meristems from cold injuries and dehydration, while storage organs below ground drive spring regrowth when conditions become favourable. In this paper, we describe a reliable phenotyping method for winter dormancy in switchgrass using various traits including regrowth height after clipping in early fall (FRH), senescence percentage, date of spring regrowth (SRD), and flowering date (FD). FRH and senescence percentage appear to be reliable indicators of the onset of winter dormancy, whereby accessions that initiated dormancy early have a low FRH and a high senescence percentage. Even though it is difficult to have an exact assessment of the duration of dormancy because it is hard to determine with precision the date of growth suspension, SRD can be used as a surrogate indicator of the duration. Flowering date showed low correlations with all the traits and biomass yield suggesting that it may not be a reliable indicator for winter dormancy in switchgrass. Combining the variables FRH, senescence, and SRD in a selection index may provide a reliable tool to phenotype winter dormancy in switchgrass. The strong correlation of these variables with biomass yield makes them useful candidates for the manipulation of the duration of dormancy to increase the growing season and consequently improving biomass production. In southern regions with mild winters, it might be possible through intense selection to develop germplasm with much reduced dormancy or even non-dormant switchgrass germplasm.
基金funded by the Xunta de Galicia(Spain) through Project XUGA 07MDS030310PR
文摘The Fabaceae(legume family) is one of the largest families of plants with a worldwide distribution and a major role in agriculture and in agroforestry.A hard seed coat impermeable to water is a typical feature of several species.Physical dormancy delays and reduces germination so that mechanical,physical and chemical scarification methods have been classically used to break seed dormancy of many species.We evaluate the effectiveness of a methodology to scarify seeds of several woody Fabaceae of ecological and economical importance,including Robinia pseudoacacia and Acacia dealbata and the shrubs Cytisus scoparius,C.multiflorus and Ulex europaeus.We describe the optimized use of a handheld rotary tool(HRT),and compare its effectiveness with other scarification methods reported to break dormancy such as boiling or dry heating.Total germination and/or speed of germination were enhanced after the application of the HRT,with germination percentages significantly higher than those achieved by other methods of scarification.Based on a thorough literature review,a mode of action for the HRT is suggested which could operate by breaking the physical and physiological dormancy of treated seeds through thecombined action of coat abrasion and moderate temperatures.Considering these results,we recommend the application of this rapid,effective,low-cost and highly reproducible HRT method to break seed dormancy and enhance germination of these species and others with similar dormancy constraints.
基金supported by National Natural Science Foundation of China(No.31830016 and 31800534)。
文摘Elucidating the regulatory mechanisms of environmental factors on seed dormancy and germination will provide guidance for tree regeneration.Toward understanding the coupled effect of light and temperature on dormancy release and germination of Pinus koraiensis seeds,we set up three light conditions(L200:200μmol m^(-2) s^(-1),L20:20μmol m^(-2) s^(-1),L0:0μm^(-2) s^(-1))and four storage temperatures[T-5:-5°C(50 days),T5:-5°C(50 days)+5°C(50 days),T25:-5°C(50 days)+5°C(50 days)+25°C(50 days),T15:-5°C(50 days)+5°C(50 days)+25°C(50 days)+15°C(50 days)]using imbibed seeds,then quantified phytohormones gibberellic acid(GA_(3))and abscisic acid(ABA)during the stratification.Germination percentage(G_(P)),mean germination time(T_(M)),and germination value(G_(V))under 25/15°C temperature and the three light conditions were then determined.Phytohormone levels and germination performances were significantly affected by light and temperature.No consistent trend was found between the phytohormone levels and G_(P) caused by light levels.Under the three light conditions,ABA concentrations in the embryo and endosperm decreased as storage temperature shifted from T-5 to T25 and increased from T25 to T15;GA_(3) decreased in nearly all four storage temperatures.G_(P) reached 40–60%in T25 storage without light irradiance.In the three light conditions,G_(P) and G_(V) were higher at T5 and T25 than at T-5 and T15;so T5 and T25 are considered as optimum storage temperatures for dormancy release and germination.At optimum temperatures,light(L200,L20)significantly increased the G_(P) and G_(V) compared with the dark(L0).At L200 and L20,significant negative correlations between G_(V) and the ABA concentrations and positive correlations between G_(V) and GA/ABA in the seed embryo were found.Temperature played a more important role in primary dormancy release and germination;light was unnecessary for primary dormancy release.Light facilitated seed germination at optimum temperatures.The dormancy release and germination of P.koraiensis seeds were controlled by a decrease in ABA concentrations or an increase in GA/ABA induced by temperature variations.
