Callose contributes to many biological processes of higher plants including pollen development,cell plate and vascular tissue formation,as well as regulating the transport function of plasmodesmata.The functions of ca...Callose contributes to many biological processes of higher plants including pollen development,cell plate and vascular tissue formation,as well as regulating the transport function of plasmodesmata.The functions of callose synthase genes in maize have been little studied.We describe a maize male-sterile mutant 39(ms39)characterized by reduced plant height.In this study,we confirmed using CRISPR/Cas9 technology that a mutation in Zm00001d043909(ZmCals12),encoding a callose synthase,is responsible for the male sterility of the ms39 mutant.Compared with male-fertile plants,callose deposition around the dyads and tetrads in ms39 anthers was significantly reduced.Increased cell autophagy observed in ms39 anthers may have been due to the premature programmed cell death of tapetal cells,leading to collapse of the anther wall structure.Disordered glucose metabolism in ms39 may have intensified autophagy in anthers.Evaluation of the ms39 gene on maize heterosis by paired-crossed experiment with 11 maize inbred lines indicated that ms39 can be used for maize hybrid seed production.展开更多
In previous study we reported that pretreatment with plasmolysis enhanced somatic embryo formation in hypocotyls of Eleutherococcus senticosus.In the present study,the expression level of callose synthase gene in embr...In previous study we reported that pretreatment with plasmolysis enhanced somatic embryo formation in hypocotyls of Eleutherococcus senticosus.In the present study,the expression level of callose synthase gene in embryos of E.senticosus in response to 2,4-D,sucrose and mannitol treatments was analyzed by RT-PCR.The results show that plasmolysis pretreatment using sucrose and mannitol significantly promoted the expression of callose synthase gene.Also,the thicker cell walls of explant plasmolyzed compared with controls were observed during the somatic embryogenesis.We suggest that the callose may make the cells in epidermis separate from neighboring cells and then develop into embryogenic potential cells.展开更多
The main defense response to Soybean mosaic virus(SMV)infection in soybean[Glycine max(L.)Merr.]is thought to be blockage of intercellular virus transport by callose deposition on plasmodesmata.But the specific regula...The main defense response to Soybean mosaic virus(SMV)infection in soybean[Glycine max(L.)Merr.]is thought to be blockage of intercellular virus transport by callose deposition on plasmodesmata.But the specific regulatory mechanism remains largely unknown.In this study,we found that hydrogen peroxide(H_(2)O_(2))signal downstream of NO was associated with the regulation of callose accumulation.Abundant H_(2)O_(2)was produced on the cell membrane and cell wall in the incompatible combination of soybean cultivar Jidou 7 and SMV strain N3,whereas no obvious H_(2)O_(2)was observed in the compatible combination of Jidou 7 and strain SC-8.When H_(2)O_(2)production was inhibited,callose accumulation induced by SMV infection decreased to a level insufficient to restrict virus transport in the incompatible combination.The H_(2)O_(2)-associated transcriptome dynamics of soybean during SMV infection was investigated.Transcriptome and functional analysis using virus-induced gene silencing showed that Gm SEOB and Gm PAP27,two genes regulated by H_(2)O_(2),functioned in resistance by positively regulating the accumulation of callose in response to SMV infection.These results lay a foundation for further research on the signal transduction and molecular regulation of callose deposition during soybean resistance to SMV infection.展开更多
Localized cell wall thickenings, so called papillae, are a common plant defense response to fungal attack at sites of penetration of the plant cell. The major constituent of papillae is callose, a (1,3)-β-glucan poly...Localized cell wall thickenings, so called papillae, are a common plant defense response to fungal attack at sites of penetration of the plant cell. The major constituent of papillae is callose, a (1,3)-β-glucan polymer, which contributes to slowing or blocking the invading fungal hyphae. In the model plant Arabidopsis thaliana, we could recently show that the overexpression of PMR4(POWDERY MILDEW RESITANT 4), which encodes a stress induced callose synthase, results in complete powdery mildew resistance. To evaluate if these findings are also transferable to monocot crops, we transiently expressed PMR4 under control of the 35S promoter in leaves of barley (Hordeum vulgare) seedlings, which were subsequently inoculated with the virulent powdery mildew Blumeria graminis f. sp. hordei. Fusion of the green fluorescent protein (GFP) to PMR4 allowed the identification of successfully transformed barley cells, which showed an increased penetration resistance to B. graminis compared to control cells that express only GFP.PMR4-GFP localized in a similar pattern at the site of attempted fungal penetration as observed inA. thaliana, which suggests that similar transport mechanisms of the callose synthase might exist in dicot and monocot plants.展开更多
During meiosis in flowering plants,degradation of the callose wall in tetrads releases newly produced microspores,which develop into mature pollen grains.In this study,we identified zbs1,a male-sterile mutant of naked...During meiosis in flowering plants,degradation of the callose wall in tetrads releases newly produced microspores,which develop into mature pollen grains.In this study,we identified zbs1,a male-sterile mutant of naked oat（Avena nuda L.）that displayed complete spikelet sterility due to inviable mature pollen.The abnormal pollen grains originated from microspores with a defective callose wall and cell plate during meiosis.The defective callose wall and cell plate of the zbs1 mutant were detected by the labeling of cell wall epitopes（β-1,3-glucan） with immunogold during meiosis,and an abnormal chromosome configuration was observed by propidium iodide staining.The mature pollen grains of the zbs1 mutant were irregular in shape,and abnormal germination was observed by scanning electron microscopy.Together,our results indicate that the cause of male sterility in zbs1 is abnormal meiosis.展开更多
The microdomains of plasmodesmata,specialized cell-wall channels responsible for communications between neighboring cells,are composed of various plasmodesmata-located proteins(PDLPs)and lipids.Here,we found that,amon...The microdomains of plasmodesmata,specialized cell-wall channels responsible for communications between neighboring cells,are composed of various plasmodesmata-located proteins(PDLPs)and lipids.Here,we found that,among all PDLP or homologous proteins in Arabidopsis thaliana genome,PDLP5 and PDLP7 possessed a C-terminal sphingolipid-binding motif,with the latter being the only member that was significantly upregulated upon turnip mosaic virus and cucumber mosaic virus infections.pdlp7mutant plants exhibited significantly reduced callose deposition,larger plasmodesmata diameters,and faster viral transmission.These plants exhibited increased glucosidase activity but no change in callose synthase activity.PDLP7 interacted specifically with glucan endo-1,3-β-glucosidase 10(BG10).Consistently,higher levels of callose deposition and slower virus transmission in bg10 mutants were observed.The interaction between PDLP7 and BG10 was found to depend on the presence of the Gnk2-homologous 1(Gn K2-1)domain at the N terminus of PDLP7 with Asp-35,Cys-42,Gln-44,and Leu-116 being essential.In vitro supplementation of callose was able to change the conformation of the Gn K2-1 domain.Our data suggest that the Gn K2-1 domain of PDLP7,in conjunction with callose and BG10,plays a key role in plasmodesmata opening and closure,which is necessary for intercellular movement of various molecules.展开更多
Extemal and internal signals can prime the plant immune system for a faster and/or stronger response to pathogen attack.β-aminobutyric acid(BABA)is an endogenous stress metabolite that induces broad-spectrum disease ...Extemal and internal signals can prime the plant immune system for a faster and/or stronger response to pathogen attack.β-aminobutyric acid(BABA)is an endogenous stress metabolite that induces broad-spectrum disease resistance in plants.BABA perception in Arabidopsis is mediated by the aspartyl tRNA synthetase IBI1,which activates priming of multiple immune responses,including callose-associated cell wall defenses that are under control by abscisic acid(ABA).However,the immediate signaling components after BABA perception by IBI1,as well as the regulatory role of ABA therein,remain unknown.Here,we have studied the early signaling events controlling IBI1-dependent BABA-induced resistance(BABAIR),using untargeted transcriptome and protein interaction analyses.Transcriptome analysis revealed that IBI1-dependent expression of BABA-IR against the biotrophic oomycete Hyaloperonospora arabidopsidis is associated with suppression of ABA-inducible abiotic stress genes.Protein interaction studies identified the VOZ1 and VOZ2 transcription factors(TFs)as IBI1-interacting partners,which are transcrip-tionally induced by ABA but suppress pathogen-induced expression of ABA-dependent genes.Furthermore,we show that VOZ TFs require nuclear localization for their contribution to BABA-IR by mediating augmented expression of callose-associated defense.Collectively,our study indicates that the IBI1-VOZ signaling module channels pathogen-induced ABA signaling toward cell wall defense while simultaneously suppressing abiotic stress-responsive genes.展开更多
Photoperiod/temperature-sensitive genic male sterility(P/TGMS)is widely applied for improving crop production.Previous investigations using the reversible male sterile(rvms)mutant showed that slow development is a gen...Photoperiod/temperature-sensitive genic male sterility(P/TGMS)is widely applied for improving crop production.Previous investigations using the reversible male sterile(rvms)mutant showed that slow development is a general mechanism for restoring fertility to P/TGMS lines in Arabidopsis.In this work,we isolated a restorer of rvms–2(res3),as the male sterility of rvms–2 was rescued by res3.Phenotype analysis and molecular cloning show that a point mutation in UPEX1 l in res3 leads to delayed secretion of callase A6 from the tapetum to the locule and tetrad callose wall degradation.Electrophoretic mobility shift assay and chromatin immunoprecipitation analysis demonstrated that the tapetal transcription factor ABORTED MICROSPORES directly regulates UPEX1 expression,revealing a pathway for tapetum secretory function.Early degradation of the callose wall in the transgenic line eliminated the fertility restoration effect of res3.The fertility of multiple known P/TGMS lines with pollen wall defects was also restored by res3.We propose that the remnant callose wall may broadly compensate for the pollen wall defects of P/TGMS lines by providing protection for pollen formation.A cellular mechanism is proposed to explain how slow development restores the fertility of P/TGMS lines in Arabidopsis.展开更多
The conditions that favor the in vitro synthesis of cellulose from tobacco BY-2 cell extracts were determined. The procedure leading to the highest yield of cellulose consisted of incubating digitonin extracts of memb...The conditions that favor the in vitro synthesis of cellulose from tobacco BY-2 cell extracts were determined. The procedure leading to the highest yield of cellulose consisted of incubating digitonin extracts of membranes from 11-day-old tobacco BY-2 cells in the presence of 1 mM UDP-glucose, 8 mM Ca^2＋ and 8 mM Mg^2＋. Under these conditions, up to nearly 40% of the polysaccharides synthesized in vitro corresponded to cellulose, the other polymer synthesized being callose. Transmission electron microscopy analysis revealed the occurrence of two types of structures in the synthetic reactions. The first type consisted of small aggregates with a diameter between 3 and 5 nm that associated to form fibrillar strings of a maximum length of 400 nm. These structures were sensitive to the acetic/nitric acid treatment of Updegraff and corresponded to callose. The second type of structures was resistant to the Updegraff reagent and corresponded to straight cellulose microfibrils of 2-3 nm in diameter and 200 nm to up to 5 μm in length. In vitro reactions performed on electron microscopy grids indicated that the minimal rate of microfibril elongation in vitro is 120 nm/min. Measurements of retardance by liquid crystal polarization microscopy as a function of time showed that small groups of microfibrils increased in retardance by up to 0.047 nm/min per pixel, confirming the formation of organized structures.展开更多
Citrus Huanglongbing,associated with Candidatus Liberibacter asiaticus(Las),is the serious disease of citrus worldwide.Here,we compared differences between leaf and root responses in Wanjincheng Orange(Citrus sinensis...Citrus Huanglongbing,associated with Candidatus Liberibacter asiaticus(Las),is the serious disease of citrus worldwide.Here,we compared differences between leaf and root responses in Wanjincheng Orange(Citrus sinensis Osbeck)to Las infection using leaf-disc grafting.Trees had no obvious symptoms in the first two months after grafting(MAG),but yellowing leaves,thickened midribs and decayed roots began to appear at 6 MAG.The Las growth rate in roots was greater than inmidribs from 2 to 6 MAG;however,by 10 MAG,it was significantly lower in roots than in midribs.Amicroscopic analysis revealed that starch accumulation,callose deposition,cellwall thickness and the number of cell layers increased in the phloem of infected trees.After Las infection,the starch content in the leaves was significantly higher than that in the roots,while the callose deposition in the midribs was 3–19 times that in the roots.A gene expression analysis showed that transcripts of callose-and starch metabolism-related genes were obviously affected by Las infection,and the pathogenesis-related genes PR1,PR2 and PR5 were significantly upregulated and downregulated in midrib and root,respectively.Our results indicated that the PR-mediated resistance response was repressed in root but activated in midrib,which may result in the more rapid Las growth in roots than in midribs during the early infection stage.展开更多
Potassium(K),an important nutrient element,can improve the stress resistance/tolerance of crops.The application of K in resisting plant-parasitic nematodes shows that the K treatment can reduce the occurrence of nemat...Potassium(K),an important nutrient element,can improve the stress resistance/tolerance of crops.The application of K in resisting plant-parasitic nematodes shows that the K treatment can reduce the occurrence of nematode diseases and increase crop yield.However,data on K_(2)SO_(4)induced rice resistance against the root-knot nematode Meloidogyne graminicola are still lacking.In this work,K_(2)SO_(4)treatment reduced galls and nematodes in rice plants and delayed the development of nematodes.Rather than affecting the attractiveness of roots to nematodes and the morphological phenotype of giant cells at feeding sites,such an effect is achieved by rapidly priming hydrogen peroxide(H_(2)O_(2))accumulation and increasing callose deposition.Meanwhile,galls and nematodes in rice roots were more in the potassium channel OsAKT11 and transporter OsHAK5 gene-deficient plants than in wild-type,while the K_(2)SO_(4)-induced resistance showed weaker in the defective plants.In addition,during the process of nematode infection,the expression of jasmonic acid(JA)/ethylene(ET)/brassinolide(BR)signaling pathway-related genes and pathogenesis-related(PR)genes OsPR1 a/OsPR1 b was up-regulated in rice after K_(2)SO_(4)treatment.In conclusion,K_(2)SO_(4)induced rice resistance against M.graminicola.The mechanism of inducing resistance was to prime the basal defense and required the participation of the K^(+)channel and transporter in rice.These laid a foundation for further study on the mechanism of rice defense against nematodes and the rational use of potassium fertilizer on improving rice resistance against nematodes in the field.展开更多
Background: Central or hypothalamic hypogonadism as an initial manifestation of Shapiro Syndrome has not been described in the literature. Herein, we report first case in which initial presentation of central hypogona...Background: Central or hypothalamic hypogonadism as an initial manifestation of Shapiro Syndrome has not been described in the literature. Herein, we report first case in which initial presentation of central hypogonadism led to a confirmed diagnosis of Shapiro Syndrome during a casual evaluation of hypothalamic pituitary anatomy with MRI of brain. Case presentation: 53 year old Caucasian man was documented to manifest Central or hypogonadotropic hypogonadism following evaluation of excessive sweating episodes, lack of libido and erectile dysfunction for a duration of several years. Brain MRI performed for assessment of the etiology documented no pituitary abnormality. Instead agenesis of Corpus Callosum was noted. The subject had been hospitalized on many occasions at this and several other medical centers with hypothermia or hyperthermia without a documentation of a definite cause. Therefore, the diagnosis of Shapiro Syndrome was made. Conclusion: This report is the first documentation of subject manifesting central, more likely to be hypothalamic rather than hypogonadotropic hypogonadism in conjunction with Shapiro Syndrome.展开更多
Callose,aβ-1,3-glucan plant cell wall polymer,regulates symplasmic channel size at plasmodesmata(PD)and plays a crucial role in a variety of plant processes.However,elucidating the molecular mechanism of PD callose h...Callose,aβ-1,3-glucan plant cell wall polymer,regulates symplasmic channel size at plasmodesmata(PD)and plays a crucial role in a variety of plant processes.However,elucidating the molecular mechanism of PD callose homeostasis is limited.We screened and identified an Arabidopsis mutant plant with excessive callose deposition at PD and found that the mutated gene wasα1-COP,a member of the coat protein I(COPI)coatomer complex.We report that loss of function ofα1-COP elevates the callose accumulation at PD by affecting subcellular protein localization of callose degradation enzyme Pd BG2.This process is linked to the functions of ERH1,an inositol phosphoryl ceramide synthase,and glucosylceramide synthase through physical interactions with theα1-COP protein.Additionally,the loss of function ofα1-COP alters the subcellular localization of ERH1 and GCS proteins,resulting in a reduction of Glc Cers and Glc HCers molecules,which are key sphingolipid(SL)species for lipid raft formation.Our findings suggest thatα1-COP protein,together with SL modifiers controlling lipid raft compositions,regulates the subcellular localization of GPI-anchored PDBG2 proteins,and hence the callose turnover at PD and symplasmic movement of biomolecules.Our findings provide the first key clue to link the COPI-mediated intracellular trafficking pathway to the callose-mediated intercellular signaling pathway through PD.展开更多
Riboflavin （vitamin B2） participates in a variety of redox processes that affect plant defense responses. Previously we have shown that riboflavin induces pathogen resistance in the absence of hypersensitive cell de...Riboflavin （vitamin B2） participates in a variety of redox processes that affect plant defense responses. Previously we have shown that riboflavin induces pathogen resistance in the absence of hypersensitive cell death （HCD） in plants. Herein, we report that riboflavin induces priming of defense responses in Arabidopsis thaliana toward infection by virulent Pseudomonas syringae pv. tomato DC3000 （Pst）. Induced resistance was mechanistically connected with the expression of defense response genes and cellular defense events, including H202 burst, HCD, and callose deposition in the plant. Riboflavin treatment and inoculation of plants with Pst were neither active but both synergized to induce defense responses. The priming process needed NPRI （essential regulator of systemic acquired resistance） and maintenance of H202 burst but was independent of salicylic acid, jasmonic acid, ethylene, and abscisic acid. Our results suggest that the role of riboflavin in priming defenses is subject to a signaling process distinct from the known pathways of hormone signal transduction.展开更多
Lily was grown worldwide as a fresh cutting flower because of its colorful petals, but its anther contained a large number of pollen grains that cause serious pollen contamination, however, pollen abortion can effecti...Lily was grown worldwide as a fresh cutting flower because of its colorful petals, but its anther contained a large number of pollen grains that cause serious pollen contamination, however, pollen abortion can effectively reduce the level of pollen pollution. Our analysis aims to use cytological observation to detect the critical stage when pollen abortion occurs and to provide comprehensive gene expression information at the transcriptional level. The result showed that pollen abortion in ‘Little Kiss’ began at the mononuclear stage and the callose that covers the microspores failed to degenerate when young pollens were released from the tetrads. In addition, compared with the normally developed one,the tapetum of ‘Little Kiss’ degraded in advance while the degradation of callose was delayed. Furthermore, 103 differentially expressed genes(DEGs) related to the advance degeneration of tapetum cells and callose were found in the expression levels, including 22 transcription factors(TFs). In particular, two β-glucanase genes(endo-1,3(4)-β-glucanase, exo-β-glucanase) responsible for callose degeneration were significantly down-regulated. These results suggested that pollen abortion may occur at mononuclear stage and that early degeneration of tapetum cells resulted in a significant down-regulation of β-glucanase genes. As a result, the callose to cover microspores impedes the formation of pollen walls, which may possibly lead to pollen abortion.展开更多
The pollen wall is a solid and variously sculptured structure. This pattern is determined inside a tetrad. During meiosis, the callose wall is formed outside of the meiocyte/microspore to form a tetrad. Then, primexin...The pollen wall is a solid and variously sculptured structure. This pattern is determined inside a tetrad. During meiosis, the callose wall is formed outside of the meiocyte/microspore to form a tetrad. Then, primexine is deposited between the callose wall and the microspore plasma membrane which will become undulated. The sporopollenin deposits on top of the undulated membrane and develops into the pollen wall pattern, while the callose wall is gradually degraded. In recent years, much progress has been made in the study of pollen wall pattern formation, at both molecular and genetic levels. In this review,we summarize these achievements mainly in Arabidopsis.展开更多
Transfer cells （TCs） are specialized cells exhibiting invaginated wall ingrowths （Wls）, thereby amplifying their plasma membrane surface area （PMSA） and hence the capacity to transport nutrients. However, it rem...Transfer cells （TCs） are specialized cells exhibiting invaginated wall ingrowths （Wls）, thereby amplifying their plasma membrane surface area （PMSA） and hence the capacity to transport nutrients. However, it remains unknown as to whether TCs play a role in biomass yield increase during evolution or domestication. Here, we examine this issue from a comparative evolutionary perspective. The cultivated tetraploid AD genome species of cotton and its A and D genome diploid progenitors displayed high, medium, and low seed and fiber biomass yield, respectively. In all three species, cells of the innermost layer of the seed coat juxtaposed to the filial tissues trans-differentiated to a TC morphology. Electron microscopic analyses revealed that these TCs are characterized by sequential formation of flange and reticulate Wls during the phase of rapid increase in seed biomass. Significantly, TCs from the tetraploid species developed substantially more flange and reticulate Wls and exhibited a higher degree of reticulate WI formation than their progenitors. Consequently, the estimated PMSA of TCs of the tetraploid species was about 4 and 70 times higher than that of TCs of the A and D genome progenitors, respectively, which correlates positively with seed and fiber biomass yield. Further, TCs with extensive Wls in the tetraploid species had much stronger expression of sucrose synthase, a key enzyme involved in TC Wl formation and function, than those from the A and D progenitors. The analyses provide a set of novel evidence that the development of TC Wls may play an important role in the increase of seed and fiber biomass yield through polyploidization during evolution.展开更多
Intercellular and supracellular communications through plasmodesmata are involved in vital processes for plant development and physiological responses. Micro- and macromolecules, including hormones, RNA, and proteins,...Intercellular and supracellular communications through plasmodesmata are involved in vital processes for plant development and physiological responses. Micro- and macromolecules, including hormones, RNA, and proteins, serve as biological information vectors that traffic through the plasmodesmata between cells. Previous studies demonstrated that the plasmodesmata are elaborately regulated, whereby a long queue of multiple signaling molecules forms. However, the mechanism by which these signals are coupled or coor- dinated in terms of simultaneous transport in a single channel remains a puzzle. In the last few years, several phytohormones that could function as both non-cell-autonomous signals and plasmodesmal regulators have been disclosed. Plasmodesmal regulators such as auxin, salicylic acid, reactive oxygen species, gibberellic acids, chitin, and jasmonic acid could regulate intercellular trafficking by adjusting plasmodesmal permeability. Here, callose, along with β-glucan synthase and β-glucanase, plays a critical role in regulating plasmodesmal permeability. Interestingly, most of the previously identified regulators are capable of diffusing through the plasmodesmata. Given the small sizes of these molecules, the plasmo- desmata are prominent intercellular channels that allow diffusion-based movement of those signaling molecules. Obviously, intercellular communication is under the control of a major mechanism, named a feedback loop, at the plasmodesmata, which mediates complicated biological behaviors. Prospective research on the mechanism of coupling micromolecules at the plasmodesmata for developmental signaling and nutrient provision will help us to understand how plants coordinate their development and photosynthetic assimilation, which is important for agriculture.展开更多
Chemical genetics as a part of chemical genomics is a powerful and fast developing approach to dissect biological processes that may be difficult to characterize using conventional genetics because of gene redundancy ...Chemical genetics as a part of chemical genomics is a powerful and fast developing approach to dissect biological processes that may be difficult to characterize using conventional genetics because of gene redundancy or lethality and, in the case of polysaccharide biosynthesis, plant flexibility. Polysaccharide synthetic enzymes are located in two main compartments--the Golgi apparatus and plasma membrane-and can be studied in vitro using membrane fractions. Here, we first developed a high-throughput assay that allowed the screening of a library of chemicals with a potential effect on glycosyltransferase activities. Out of the 4800 chemicals screened for their effect on Golgi glucosyltransferases, 66 compounds from the primary screen had an effect on carbohydrate biosynthesis. Ten of these compounds were confirmed to inhibit glucose incorporation after a second screen. One compound exhibiting a strong inhibition effect （ID 6240780 named chemical A） was selected and further studied. It reversibly inhibits the transfer of glucose from UDP-glucose by Golgi membranes, but activates the plasma membrane-bound callose synthase. The inhibition effect is dependent on the chemical structure of the compound, which does not affect endomembrane morphology of the plant cells, but causes changes in cell wall composition. Chemical A represents a novel drug with a great potential for the study of the mechanisms of Golgi and plasma membrane-bound glucosyltransferases.展开更多
基金supported by the National Natural Science Foundation of China(31771876)the Sichuan Province Science and Technology Program(2021YFYZ0011,2021YFYZ0017).
文摘Callose contributes to many biological processes of higher plants including pollen development,cell plate and vascular tissue formation,as well as regulating the transport function of plasmodesmata.The functions of callose synthase genes in maize have been little studied.We describe a maize male-sterile mutant 39(ms39)characterized by reduced plant height.In this study,we confirmed using CRISPR/Cas9 technology that a mutation in Zm00001d043909(ZmCals12),encoding a callose synthase,is responsible for the male sterility of the ms39 mutant.Compared with male-fertile plants,callose deposition around the dyads and tetrads in ms39 anthers was significantly reduced.Increased cell autophagy observed in ms39 anthers may have been due to the premature programmed cell death of tapetal cells,leading to collapse of the anther wall structure.Disordered glucose metabolism in ms39 may have intensified autophagy in anthers.Evaluation of the ms39 gene on maize heterosis by paired-crossed experiment with 11 maize inbred lines indicated that ms39 can be used for maize hybrid seed production.
基金supported by the 948 Program of State Forestry Administration (No2009-4-26)co-sponsored by SRF for ROCS and the National Natural Science Foundation (No 30972390) of China
文摘In previous study we reported that pretreatment with plasmolysis enhanced somatic embryo formation in hypocotyls of Eleutherococcus senticosus.In the present study,the expression level of callose synthase gene in embryos of E.senticosus in response to 2,4-D,sucrose and mannitol treatments was analyzed by RT-PCR.The results show that plasmolysis pretreatment using sucrose and mannitol significantly promoted the expression of callose synthase gene.Also,the thicker cell walls of explant plasmolyzed compared with controls were observed during the somatic embryogenesis.We suggest that the callose may make the cells in epidermis separate from neighboring cells and then develop into embryogenic potential cells.
基金supported by the National Natural Science Foundation of China(30971706 and31471421)"973"Preliminary Program(2014CB160318)Hebei Natural Science Foundation(C2020204132)。
文摘The main defense response to Soybean mosaic virus(SMV)infection in soybean[Glycine max(L.)Merr.]is thought to be blockage of intercellular virus transport by callose deposition on plasmodesmata.But the specific regulatory mechanism remains largely unknown.In this study,we found that hydrogen peroxide(H_(2)O_(2))signal downstream of NO was associated with the regulation of callose accumulation.Abundant H_(2)O_(2)was produced on the cell membrane and cell wall in the incompatible combination of soybean cultivar Jidou 7 and SMV strain N3,whereas no obvious H_(2)O_(2)was observed in the compatible combination of Jidou 7 and strain SC-8.When H_(2)O_(2)production was inhibited,callose accumulation induced by SMV infection decreased to a level insufficient to restrict virus transport in the incompatible combination.The H_(2)O_(2)-associated transcriptome dynamics of soybean during SMV infection was investigated.Transcriptome and functional analysis using virus-induced gene silencing showed that Gm SEOB and Gm PAP27,two genes regulated by H_(2)O_(2),functioned in resistance by positively regulating the accumulation of callose in response to SMV infection.These results lay a foundation for further research on the signal transduction and molecular regulation of callose deposition during soybean resistance to SMV infection.
文摘Localized cell wall thickenings, so called papillae, are a common plant defense response to fungal attack at sites of penetration of the plant cell. The major constituent of papillae is callose, a (1,3)-β-glucan polymer, which contributes to slowing or blocking the invading fungal hyphae. In the model plant Arabidopsis thaliana, we could recently show that the overexpression of PMR4(POWDERY MILDEW RESITANT 4), which encodes a stress induced callose synthase, results in complete powdery mildew resistance. To evaluate if these findings are also transferable to monocot crops, we transiently expressed PMR4 under control of the 35S promoter in leaves of barley (Hordeum vulgare) seedlings, which were subsequently inoculated with the virulent powdery mildew Blumeria graminis f. sp. hordei. Fusion of the green fluorescent protein (GFP) to PMR4 allowed the identification of successfully transformed barley cells, which showed an increased penetration resistance to B. graminis compared to control cells that express only GFP.PMR4-GFP localized in a similar pattern at the site of attempted fungal penetration as observed inA. thaliana, which suggests that similar transport mechanisms of the callose synthase might exist in dicot and monocot plants.
基金supported by the Natural Science Foundation of Hebei Province,China(C2004000747)
文摘During meiosis in flowering plants,degradation of the callose wall in tetrads releases newly produced microspores,which develop into mature pollen grains.In this study,we identified zbs1,a male-sterile mutant of naked oat（Avena nuda L.）that displayed complete spikelet sterility due to inviable mature pollen.The abnormal pollen grains originated from microspores with a defective callose wall and cell plate during meiosis.The defective callose wall and cell plate of the zbs1 mutant were detected by the labeling of cell wall epitopes（β-1,3-glucan） with immunogold during meiosis,and an abnormal chromosome configuration was observed by propidium iodide staining.The mature pollen grains of the zbs1 mutant were irregular in shape,and abnormal germination was observed by scanning electron microscopy.Together,our results indicate that the cause of male sterility in zbs1 is abnormal meiosis.
基金supported by the National Natural Science Foundation of China(31830057)。
文摘The microdomains of plasmodesmata,specialized cell-wall channels responsible for communications between neighboring cells,are composed of various plasmodesmata-located proteins(PDLPs)and lipids.Here,we found that,among all PDLP or homologous proteins in Arabidopsis thaliana genome,PDLP5 and PDLP7 possessed a C-terminal sphingolipid-binding motif,with the latter being the only member that was significantly upregulated upon turnip mosaic virus and cucumber mosaic virus infections.pdlp7mutant plants exhibited significantly reduced callose deposition,larger plasmodesmata diameters,and faster viral transmission.These plants exhibited increased glucosidase activity but no change in callose synthase activity.PDLP7 interacted specifically with glucan endo-1,3-β-glucosidase 10(BG10).Consistently,higher levels of callose deposition and slower virus transmission in bg10 mutants were observed.The interaction between PDLP7 and BG10 was found to depend on the presence of the Gnk2-homologous 1(Gn K2-1)domain at the N terminus of PDLP7 with Asp-35,Cys-42,Gln-44,and Leu-116 being essential.In vitro supplementation of callose was able to change the conformation of the Gn K2-1 domain.Our data suggest that the Gn K2-1 domain of PDLP7,in conjunction with callose and BG10,plays a key role in plasmodesmata opening and closure,which is necessary for intercellular movement of various molecules.
基金the European Research Council(ERC,no.309944,“Prime-A-Plant”)J.T..a Research Leadership Award from the Leverhulme Trust(no.RL-2012-042)+1 种基金J.T..a BBSRC-IPA grant to J.T.(BB/P006698/1)J.T..and an ERC-PoC grant to J.T.(no.824985,“ChemPrime”).
文摘Extemal and internal signals can prime the plant immune system for a faster and/or stronger response to pathogen attack.β-aminobutyric acid(BABA)is an endogenous stress metabolite that induces broad-spectrum disease resistance in plants.BABA perception in Arabidopsis is mediated by the aspartyl tRNA synthetase IBI1,which activates priming of multiple immune responses,including callose-associated cell wall defenses that are under control by abscisic acid(ABA).However,the immediate signaling components after BABA perception by IBI1,as well as the regulatory role of ABA therein,remain unknown.Here,we have studied the early signaling events controlling IBI1-dependent BABA-induced resistance(BABAIR),using untargeted transcriptome and protein interaction analyses.Transcriptome analysis revealed that IBI1-dependent expression of BABA-IR against the biotrophic oomycete Hyaloperonospora arabidopsidis is associated with suppression of ABA-inducible abiotic stress genes.Protein interaction studies identified the VOZ1 and VOZ2 transcription factors(TFs)as IBI1-interacting partners,which are transcrip-tionally induced by ABA but suppress pathogen-induced expression of ABA-dependent genes.Furthermore,we show that VOZ TFs require nuclear localization for their contribution to BABA-IR by mediating augmented expression of callose-associated defense.Collectively,our study indicates that the IBI1-VOZ signaling module channels pathogen-induced ABA signaling toward cell wall defense while simultaneously suppressing abiotic stress-responsive genes.
基金supported by grants from the National Natural Science Foundation of China(31930009,31900260)the Shanghai Municipal Education Commission(2019-01-07-00-02-E00006)the Science and Technology Commission of Shanghai Municipality(18DZ2260500 and 17DZ2252700)。
文摘Photoperiod/temperature-sensitive genic male sterility(P/TGMS)is widely applied for improving crop production.Previous investigations using the reversible male sterile(rvms)mutant showed that slow development is a general mechanism for restoring fertility to P/TGMS lines in Arabidopsis.In this work,we isolated a restorer of rvms–2(res3),as the male sterility of rvms–2 was rescued by res3.Phenotype analysis and molecular cloning show that a point mutation in UPEX1 l in res3 leads to delayed secretion of callase A6 from the tapetum to the locule and tetrad callose wall degradation.Electrophoretic mobility shift assay and chromatin immunoprecipitation analysis demonstrated that the tapetal transcription factor ABORTED MICROSPORES directly regulates UPEX1 expression,revealing a pathway for tapetum secretory function.Early degradation of the callose wall in the transgenic line eliminated the fertility restoration effect of res3.The fertility of multiple known P/TGMS lines with pollen wall defects was also restored by res3.We propose that the remnant callose wall may broadly compensate for the pollen wall defects of P/TGMS lines by providing protection for pollen formation.A cellular mechanism is proposed to explain how slow development restores the fertility of P/TGMS lines in Arabidopsis.
基金Supported by the Netherlands Organization for Scientific Research (NWO), Physical Biology Program 2,project number 805.47.065,the Swedish Centre for Biomimetic Fibre Engineering (Biomime), and the European Cooperation in Science and Technology (COST) Short term scientificmission(STSM) action E50
文摘The conditions that favor the in vitro synthesis of cellulose from tobacco BY-2 cell extracts were determined. The procedure leading to the highest yield of cellulose consisted of incubating digitonin extracts of membranes from 11-day-old tobacco BY-2 cells in the presence of 1 mM UDP-glucose, 8 mM Ca^2＋ and 8 mM Mg^2＋. Under these conditions, up to nearly 40% of the polysaccharides synthesized in vitro corresponded to cellulose, the other polymer synthesized being callose. Transmission electron microscopy analysis revealed the occurrence of two types of structures in the synthetic reactions. The first type consisted of small aggregates with a diameter between 3 and 5 nm that associated to form fibrillar strings of a maximum length of 400 nm. These structures were sensitive to the acetic/nitric acid treatment of Updegraff and corresponded to callose. The second type of structures was resistant to the Updegraff reagent and corresponded to straight cellulose microfibrils of 2-3 nm in diameter and 200 nm to up to 5 μm in length. In vitro reactions performed on electron microscopy grids indicated that the minimal rate of microfibril elongation in vitro is 120 nm/min. Measurements of retardance by liquid crystal polarization microscopy as a function of time showed that small groups of microfibrils increased in retardance by up to 0.047 nm/min per pixel, confirming the formation of organized structures.
基金supported by grants from the National Key R&D Program of China(Grant No.2018YFD0201500)the Earmarked Fund for the China Agriculture Research System(Grant No.CARS26)the Natural Science Foundation Project of Chongqing(Grant No.cstc2017jcyjBX0020).
文摘Citrus Huanglongbing,associated with Candidatus Liberibacter asiaticus(Las),is the serious disease of citrus worldwide.Here,we compared differences between leaf and root responses in Wanjincheng Orange(Citrus sinensis Osbeck)to Las infection using leaf-disc grafting.Trees had no obvious symptoms in the first two months after grafting(MAG),but yellowing leaves,thickened midribs and decayed roots began to appear at 6 MAG.The Las growth rate in roots was greater than inmidribs from 2 to 6 MAG;however,by 10 MAG,it was significantly lower in roots than in midribs.Amicroscopic analysis revealed that starch accumulation,callose deposition,cellwall thickness and the number of cell layers increased in the phloem of infected trees.After Las infection,the starch content in the leaves was significantly higher than that in the roots,while the callose deposition in the midribs was 3–19 times that in the roots.A gene expression analysis showed that transcripts of callose-and starch metabolism-related genes were obviously affected by Las infection,and the pathogenesis-related genes PR1,PR2 and PR5 were significantly upregulated and downregulated in midrib and root,respectively.Our results indicated that the PR-mediated resistance response was repressed in root but activated in midrib,which may result in the more rapid Las growth in roots than in midribs during the early infection stage.
基金supported by the Natural Science Foundation of China(32172382,31801716,and 31571986)the National Key Research and Development Program of China(2021YFC2600404)the Scientific Research Project of Hunan Provincial Department of Education of China(19B259)。
文摘Potassium(K),an important nutrient element,can improve the stress resistance/tolerance of crops.The application of K in resisting plant-parasitic nematodes shows that the K treatment can reduce the occurrence of nematode diseases and increase crop yield.However,data on K_(2)SO_(4)induced rice resistance against the root-knot nematode Meloidogyne graminicola are still lacking.In this work,K_(2)SO_(4)treatment reduced galls and nematodes in rice plants and delayed the development of nematodes.Rather than affecting the attractiveness of roots to nematodes and the morphological phenotype of giant cells at feeding sites,such an effect is achieved by rapidly priming hydrogen peroxide(H_(2)O_(2))accumulation and increasing callose deposition.Meanwhile,galls and nematodes in rice roots were more in the potassium channel OsAKT11 and transporter OsHAK5 gene-deficient plants than in wild-type,while the K_(2)SO_(4)-induced resistance showed weaker in the defective plants.In addition,during the process of nematode infection,the expression of jasmonic acid(JA)/ethylene(ET)/brassinolide(BR)signaling pathway-related genes and pathogenesis-related(PR)genes OsPR1 a/OsPR1 b was up-regulated in rice after K_(2)SO_(4)treatment.In conclusion,K_(2)SO_(4)induced rice resistance against M.graminicola.The mechanism of inducing resistance was to prime the basal defense and required the participation of the K^(+)channel and transporter in rice.These laid a foundation for further study on the mechanism of rice defense against nematodes and the rational use of potassium fertilizer on improving rice resistance against nematodes in the field.
文摘Background: Central or hypothalamic hypogonadism as an initial manifestation of Shapiro Syndrome has not been described in the literature. Herein, we report first case in which initial presentation of central hypogonadism led to a confirmed diagnosis of Shapiro Syndrome during a casual evaluation of hypothalamic pituitary anatomy with MRI of brain. Case presentation: 53 year old Caucasian man was documented to manifest Central or hypogonadotropic hypogonadism following evaluation of excessive sweating episodes, lack of libido and erectile dysfunction for a duration of several years. Brain MRI performed for assessment of the etiology documented no pituitary abnormality. Instead agenesis of Corpus Callosum was noted. The subject had been hospitalized on many occasions at this and several other medical centers with hypothermia or hyperthermia without a documentation of a definite cause. Therefore, the diagnosis of Shapiro Syndrome was made. Conclusion: This report is the first documentation of subject manifesting central, more likely to be hypothalamic rather than hypogonadotropic hypogonadism in conjunction with Shapiro Syndrome.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea Government(MSIT)(Grant Nos.NRF 2018R1A2A1A05077295,2020M3A9I4038352,2022R1A2C3010331,2020R1A6A1A03044344,and 2022R1A 5A1031361)a grant from the New Breeding Technologies Development Program(Grant No.PJ01653202),Rural Development Administration(RDA),Republic of Korea。
文摘Callose,aβ-1,3-glucan plant cell wall polymer,regulates symplasmic channel size at plasmodesmata(PD)and plays a crucial role in a variety of plant processes.However,elucidating the molecular mechanism of PD callose homeostasis is limited.We screened and identified an Arabidopsis mutant plant with excessive callose deposition at PD and found that the mutated gene wasα1-COP,a member of the coat protein I(COPI)coatomer complex.We report that loss of function ofα1-COP elevates the callose accumulation at PD by affecting subcellular protein localization of callose degradation enzyme Pd BG2.This process is linked to the functions of ERH1,an inositol phosphoryl ceramide synthase,and glucosylceramide synthase through physical interactions with theα1-COP protein.Additionally,the loss of function ofα1-COP alters the subcellular localization of ERH1 and GCS proteins,resulting in a reduction of Glc Cers and Glc HCers molecules,which are key sphingolipid(SL)species for lipid raft formation.Our findings suggest thatα1-COP protein,together with SL modifiers controlling lipid raft compositions,regulates the subcellular localization of GPI-anchored PDBG2 proteins,and hence the callose turnover at PD and symplasmic movement of biomolecules.Our findings provide the first key clue to link the COPI-mediated intracellular trafficking pathway to the callose-mediated intercellular signaling pathway through PD.
基金Supported by the National Science Fund for Distinguished Young Scholars (30525088)the State Key Basic Research and Development Plan of China (2006CB101902)+1 种基金the National Natural Science Foundation of China (30771441)the Hi-Tech Research and Development Program of China (2006AA10Z430).
文摘Riboflavin （vitamin B2） participates in a variety of redox processes that affect plant defense responses. Previously we have shown that riboflavin induces pathogen resistance in the absence of hypersensitive cell death （HCD） in plants. Herein, we report that riboflavin induces priming of defense responses in Arabidopsis thaliana toward infection by virulent Pseudomonas syringae pv. tomato DC3000 （Pst）. Induced resistance was mechanistically connected with the expression of defense response genes and cellular defense events, including H202 burst, HCD, and callose deposition in the plant. Riboflavin treatment and inoculation of plants with Pst were neither active but both synergized to induce defense responses. The priming process needed NPRI （essential regulator of systemic acquired resistance） and maintenance of H202 burst but was independent of salicylic acid, jasmonic acid, ethylene, and abscisic acid. Our results suggest that the role of riboflavin in priming defenses is subject to a signaling process distinct from the known pathways of hormone signal transduction.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Fundamental Research Funds for the Central Universities(Grant No.KYTZ201602)+1 种基金the High Level Talent Project of the Top Six Talents in Jiangsu(Grant No.NY-077)the earmarked fund for germplasm resources of Nanjing Agricultural University(Grant No.KYZZ201920)。
文摘Lily was grown worldwide as a fresh cutting flower because of its colorful petals, but its anther contained a large number of pollen grains that cause serious pollen contamination, however, pollen abortion can effectively reduce the level of pollen pollution. Our analysis aims to use cytological observation to detect the critical stage when pollen abortion occurs and to provide comprehensive gene expression information at the transcriptional level. The result showed that pollen abortion in ‘Little Kiss’ began at the mononuclear stage and the callose that covers the microspores failed to degenerate when young pollens were released from the tetrads. In addition, compared with the normally developed one,the tapetum of ‘Little Kiss’ degraded in advance while the degradation of callose was delayed. Furthermore, 103 differentially expressed genes(DEGs) related to the advance degeneration of tapetum cells and callose were found in the expression levels, including 22 transcription factors(TFs). In particular, two β-glucanase genes(endo-1,3(4)-β-glucanase, exo-β-glucanase) responsible for callose degeneration were significantly down-regulated. These results suggested that pollen abortion may occur at mononuclear stage and that early degeneration of tapetum cells resulted in a significant down-regulation of β-glucanase genes. As a result, the callose to cover microspores impedes the formation of pollen walls, which may possibly lead to pollen abortion.
基金supported by the Major Research Plan from the Ministry of Science and Technology of China(2013CB945100)the National Natural Foundation of China(31300262)
文摘The pollen wall is a solid and variously sculptured structure. This pattern is determined inside a tetrad. During meiosis, the callose wall is formed outside of the meiocyte/microspore to form a tetrad. Then, primexine is deposited between the callose wall and the microspore plasma membrane which will become undulated. The sporopollenin deposits on top of the undulated membrane and develops into the pollen wall pattern, while the callose wall is gradually degraded. In recent years, much progress has been made in the study of pollen wall pattern formation, at both molecular and genetic levels. In this review,we summarize these achievements mainly in Arabidopsis.
文摘Transfer cells （TCs） are specialized cells exhibiting invaginated wall ingrowths （Wls）, thereby amplifying their plasma membrane surface area （PMSA） and hence the capacity to transport nutrients. However, it remains unknown as to whether TCs play a role in biomass yield increase during evolution or domestication. Here, we examine this issue from a comparative evolutionary perspective. The cultivated tetraploid AD genome species of cotton and its A and D genome diploid progenitors displayed high, medium, and low seed and fiber biomass yield, respectively. In all three species, cells of the innermost layer of the seed coat juxtaposed to the filial tissues trans-differentiated to a TC morphology. Electron microscopic analyses revealed that these TCs are characterized by sequential formation of flange and reticulate Wls during the phase of rapid increase in seed biomass. Significantly, TCs from the tetraploid species developed substantially more flange and reticulate Wls and exhibited a higher degree of reticulate WI formation than their progenitors. Consequently, the estimated PMSA of TCs of the tetraploid species was about 4 and 70 times higher than that of TCs of the A and D genome progenitors, respectively, which correlates positively with seed and fiber biomass yield. Further, TCs with extensive Wls in the tetraploid species had much stronger expression of sucrose synthase, a key enzyme involved in TC Wl formation and function, than those from the A and D progenitors. The analyses provide a set of novel evidence that the development of TC Wls may play an important role in the increase of seed and fiber biomass yield through polyploidization during evolution.
文摘Intercellular and supracellular communications through plasmodesmata are involved in vital processes for plant development and physiological responses. Micro- and macromolecules, including hormones, RNA, and proteins, serve as biological information vectors that traffic through the plasmodesmata between cells. Previous studies demonstrated that the plasmodesmata are elaborately regulated, whereby a long queue of multiple signaling molecules forms. However, the mechanism by which these signals are coupled or coor- dinated in terms of simultaneous transport in a single channel remains a puzzle. In the last few years, several phytohormones that could function as both non-cell-autonomous signals and plasmodesmal regulators have been disclosed. Plasmodesmal regulators such as auxin, salicylic acid, reactive oxygen species, gibberellic acids, chitin, and jasmonic acid could regulate intercellular trafficking by adjusting plasmodesmal permeability. Here, callose, along with β-glucan synthase and β-glucanase, plays a critical role in regulating plasmodesmal permeability. Interestingly, most of the previously identified regulators are capable of diffusing through the plasmodesmata. Given the small sizes of these molecules, the plasmo- desmata are prominent intercellular channels that allow diffusion-based movement of those signaling molecules. Obviously, intercellular communication is under the control of a major mechanism, named a feedback loop, at the plasmodesmata, which mediates complicated biological behaviors. Prospective research on the mechanism of coupling micromolecules at the plasmodesmata for developmental signaling and nutrient provision will help us to understand how plants coordinate their development and photosynthetic assimilation, which is important for agriculture.
基金This work supported by grants DBI-0211797 （to N.V.R.） and MCB- 0515963 （to N.V.R.）from the National Science Foundation Plant Genome Research Program.We thank Dr Somerville （Carnegie Institution, Stanford, CA） and Dr Dupree （University of Cambridge, UK） for the seeds of transgenic plants. No conflict of interest declared.
文摘Chemical genetics as a part of chemical genomics is a powerful and fast developing approach to dissect biological processes that may be difficult to characterize using conventional genetics because of gene redundancy or lethality and, in the case of polysaccharide biosynthesis, plant flexibility. Polysaccharide synthetic enzymes are located in two main compartments--the Golgi apparatus and plasma membrane-and can be studied in vitro using membrane fractions. Here, we first developed a high-throughput assay that allowed the screening of a library of chemicals with a potential effect on glycosyltransferase activities. Out of the 4800 chemicals screened for their effect on Golgi glucosyltransferases, 66 compounds from the primary screen had an effect on carbohydrate biosynthesis. Ten of these compounds were confirmed to inhibit glucose incorporation after a second screen. One compound exhibiting a strong inhibition effect （ID 6240780 named chemical A） was selected and further studied. It reversibly inhibits the transfer of glucose from UDP-glucose by Golgi membranes, but activates the plasma membrane-bound callose synthase. The inhibition effect is dependent on the chemical structure of the compound, which does not affect endomembrane morphology of the plant cells, but causes changes in cell wall composition. Chemical A represents a novel drug with a great potential for the study of the mechanisms of Golgi and plasma membrane-bound glucosyltransferases.
