In order to better understand the cultural route, biochemical and nutritional composition of two ecotypes of fonio, a study was carried out in village of Tambananing located approximately 7 km from Sédhiou. The o...In order to better understand the cultural route, biochemical and nutritional composition of two ecotypes of fonio, a study was carried out in village of Tambananing located approximately 7 km from Sédhiou. The objective of studies was to determine nutritional composition of two ecotypes of fonio: the first called momo in short-cycle mandinka (75 - 90 days) and the other called medium-cycle dibong (90 - 110 days). For this, samples of two ecotypes were collected in an experimental field which was split into two equal parts, one sown with the momo ecotype and the other with the dibong ecotype. The nutritional composition (sugars, fats, proteins, minerals, ash, etc.) and the physicochemical properties (pH, humidity, water activity, color, etc.) of fonio’s were determined by appropriate physicochemical methods. The two ecotypes exhibited quite similar physicochemical properties. The levels of biochemical compounds were relatively close with protein contents of 7.05 ± 0.06 mg/100g for the momo ecotype and of 8.02 ± 0.04 mg/100g for the dibong ecotype, in carbohydrates (76.37 ± 1.2 mg/100g for momo and 78.7 ± 1.5 mg/100g for dibong) and in fat (2.92 ± 0.05 mg/100g for momo and 3.14 ± 0.004 mg/100g for dibong). Identical mineral element contents were found except for iron, an element for which the contents were 10.80 ± 0.008 mg/100g for the momo ecotype and 99.59 ± 0.005 mg/100g for the dibong ecotype. Thus, two ecotypes of fonio present a fairly interesting nutritional composition and their consumption deserves to be popularized and could contribute effectively to fight against the problems of malnutrition of certain vulnerable groups.展开更多
This study was conducted from June 2021 to January 2023 to assess the genetic diversity of giant African snails in the western highlands of Cameroon. A total of 652 snails were randomly collected from the wild in thre...This study was conducted from June 2021 to January 2023 to assess the genetic diversity of giant African snails in the western highlands of Cameroon. A total of 652 snails were randomly collected from the wild in three localities in the western highlands (Bafang, Bafoussam, and Santchou). The study revealed significant variations in morphobiometric characteristics both between species and localities. The predominant shell coloration was brownish with yellow zigzag stripes (65%), while the dominant coloration for shell openings was whitish (48%). Regarding foot coloration, both brown with spotted black and black with spotted brown colorations were dominant (29%). The highest recorded live weight of snails (39.33 ± 34) was found in the species Archachatina marginata. In terms of length measurements (in mm), the length of the right and left sides of the shell was higher in the A. fulica species (49.8 ± 19.7 mm and 40.07 ± 18 mm, respectively). Bafang exhibited the highest values for shell length (56 ± 11 mm) and shell width (46.52 ± 11.46 mm). A. fulica recorded the highest shell length (81.5 ± 27 mm), while A. marginata recorded the highest shell width (49.6 ± 12.1 mm), with the highest values observed in A. fulica from fulica having a slightly higher aperture width value (30 ± 10 mm) compared to A. marginata, while A. marginata had the highest value for aperture length measurement (54.5 ± 12 mm). A. fulica also exhibited the highest values for the length from apex to the first whorl and the length from left to right of the first whorl (43.2 ± 18 mm and 39 ± 19.8 mm, respectively). Strong and positive correlations were observed between the live weight of snails and body measurements regardless of species, except for the number of whorls, which showed very weak or negative correlations with other body measurements. The results of Hierarchical Cluster Analysis (HCA) revealed three distinct snail population types. These findings provide valuable insights into the phenotypic diversity of edible land snails in the western highlands of Cameroon and can be considered in improvement and conservation programs aimed at enhancing snail meat yield.展开更多
The basin of Lake Titicaca is a faba bean-producing microregion of Bolivia where the crop is destined for export. The most commonly cultivated ecotypes “Gigante de Copacabana” and “Usnayo” are affected by diseases...The basin of Lake Titicaca is a faba bean-producing microregion of Bolivia where the crop is destined for export. The most commonly cultivated ecotypes “Gigante de Copacabana” and “Usnayo” are affected by diseases that can cause production losses. The aims of the present work were to identify the causal agents of leaf spot affecting these ecotypes, to record disease intensity levels, and to estimate their effect on production. In 2004 and 2005, leaflet, stem and pod samples were taken from faba bean plants with leaf spot growing in the Lake Titicaca area, and from plants in an experimental plot established to determine the effect of five different treatments on production and disease intensity: T1 = Control;T2 = seed treatment with Trichoderma sp. + alternate foliar spraying with benomyl and mancozeb;T3 = seed treatment with fludioxanil/metalaxyl M + alternate foliar spraying with benomyl and mancozeb;T4 = foliar spraying with Trichoderma sp.;T5 = alternate foliar spraying with cymoxanyl and mancozeb-chlorothalonil. Microscopic analysis of the samples revealed the presence of new fungal pathogens for faba beans in Bolivia (Cladosporium sp., and Lepthosphaerulina sp.) as well as emerging fungal pathogens (Botrytis cinerea, B. fabae, Ascochyta fabae, Alternaria sp. and Cercospora sp.). None of the treatments affected the disease progression curve (DPC) for incidence, although effects were seen with respect to disease severity. The seed + foliar treatments (T2 and T3) were more effective at controlling disease than leaf treatments on their own (T4 and T5). Modelling analysis showed faba bean leaf spot disease to be moderately destructive. Compared to chemical treatments, biocontrol with Trichoderma spp. preliminary was found to provide good control of the disease. Losses due to leaf spot disease of 36% were recorded, and a strong correlation detected between yield and disease severity.展开更多
The roots and leaves of four reed ecotypes (Phragmites communis Trinius) growing in the desertregions of northwest China were determined for the levels of abscisic acid (ABA) and cytokinins [isopenteny-ladenosine (iPA...The roots and leaves of four reed ecotypes (Phragmites communis Trinius) growing in the desertregions of northwest China were determined for the levels of abscisic acid (ABA) and cytokinins [isopenteny-ladenosine (iPA) and zeatin riboside (ZR) ] using an展开更多
To determine the size and the density of stomata among different environments, we conducted anatomical analyses using Aster hispidus var. hispidus (open field), As. hispidus var. leptocladus (serpentine soil), and As....To determine the size and the density of stomata among different environments, we conducted anatomical analyses using Aster hispidus var. hispidus (open field), As. hispidus var. leptocladus (serpentine soil), and As. hispidus var. insularis (coastal). The stomatal size was not significantly different among these ecotypes but the density of stomata in the serpentine and coastal ecotypes was significantly lower than that of As. hispidus var. hispidus, which suggests that these ecotypes have experienced selection that reduced the density of stomata for adaptation to the dry conditions of serpentine and coastal areas.展开更多
Aims The two coexisting Leymus chinensis ecotypes exhibit remarkable divergences in adaptive strategies under drought and salinity in semi-humid meadows and semi-arid steppes.In order to detect the major genetic and e...Aims The two coexisting Leymus chinensis ecotypes exhibit remarkable divergences in adaptive strategies under drought and salinity in semi-humid meadows and semi-arid steppes.In order to detect the major genetic and environmental factors dominating the intraspecific phenotype variations and ecotype formation,the questions regarding the two distinct phenotypic forms(ecotypes)in L.chin-ensis were addressed:(i)did environments drive the L.chinensis ecotype formation?(ii)was there a molecular basis for the morphological divergence between the two ecotypes?(iii)which driving force dominated the intraspecies divergence,divergent natural selection,genetic drift or stabilizing selection?Methods We applied a series experiments on demographical,morphological and physiological traits of two Leymus chinensis ecotypes with gray green(GG)and yellow green(YG)leaf color in nine wild sites along a longitudinal gradient from 114°to 124°E in northeast China.The environmental data including mean annual precipitation,mean annual temperature,elevation and soil properties were collected.We compared the differences of morphological,physiological and genetic differentiations between the two ecotypes.Important FindingsThe GG type exhibited stronger fitness than YG type from the population densities,morphological traits(e.g.shoot height,leaf area,leaf and seed weights et al.),leaf mass per area(LMA)and physiological traits[relative water content(RWC),proline,soluble sugar contents].Most of above phenotypes(e.g.total shoot densities,spike length et al.)were significantly correlated with mean annual precipitation,mean annual temperature and soil water content(SWC),rarely a correlated with soil pH and soil nutrient.Transplanted populations showed convergence trend by their leaf chlorophyll contents and osmotic adjustments(proline and soluble sugar contents)in the greenhouse,but still exhibited their divergences between two ecotypes in the outdoor transplantation,suggesting that whether L.chinensis ecotype differentiated could be largely affected by the environmental conditions.Furthermore,by the comparison result of quantitative genetic variation(Q_(ST))values from phenotypes with theoretical neutral genetic differentiation(F_(ST)),differentiation in phenotypic traits greatly surpassed neutral predictions,implying that directional natural selection played a crucial role in L.chinen-sis ecotype differentiation.In addition,microsatellite analysis from Neighbor-joining tree and Bayesian assignment generated into two groups according to ecotypes,indicating molecular genetic differentiation also propelled the two ecotypes divergence.We conclude that L.chinensis population variations were driven by combing divergent natural selection(precipitation,temperature and SWCs)along the large-scale gradient and significantly intrinsic genetic differentiation.展开更多
We investigated whether plant ecotype might affect aphid performance and behavioi. The probing behaviors of the polyphagous aphid Myzus persicae and the oligophagous aphid Brevicoryne brassicae on two ecotypes of Arab...We investigated whether plant ecotype might affect aphid performance and behavioi. The probing behaviors of the polyphagous aphid Myzus persicae and the oligophagous aphid Brevicoryne brassicae on two ecotypes of Arabidopsis thaliana, WS and Col-0 were recorded using the direct current electrical penetration graph method (DC-EPG). Myzus persicae displayed a significant preference for the WS ecotype but was not greatly disturbed on Col-0, while B. brassicae discriminated between the two A. thaliana ecotypes, feeding less on WS than on Col-0. A Principal Component Analysis of aphid probing behavior data recorded on Col-0 and WS ecotypes showed that the one of M. persicae was positively correlated with the phloem ingestion phases while the one of B. brassicae was more related to nonfeeding phase. The survival of the aphid species was followed during early larval stages on the two ecotypes and a significantly higher mortality was observed of B. brassicae neonates compared to M. persicae. Both reared on WS. Moreover, transcriptomic analysis of non infested plant leaves from both ecotypes was monitored and underlined constitutive differences between Col-0 and WS gene expression that might explain the different aphid behaviors. Among a unigene set comprising 39 042 sequences for A. thaliana, 6% were differently expressed affecting, for example, the secondary metabolites and cell wall pathways: two third upregulated in WS and one third upregulated in Col-0. Thus, the "ecotype” variable should be taken into account when setting up a plant-insect experimental research.展开更多
Genetic diversity of two chicken ecotypes from Ismailia-Egypt (ISM) and Taif-Saudi Arabia (TA) was evaluated using 39 microsatellites. DNA was extracted from blood of 25 chickens/ecotype. The number of alleles was 157...Genetic diversity of two chicken ecotypes from Ismailia-Egypt (ISM) and Taif-Saudi Arabia (TA) was evaluated using 39 microsatellites. DNA was extracted from blood of 25 chickens/ecotype. The number of alleles was 157 and 138, the number of alleles/locus averaged 4.2±2.2 and 3.6±1.6, and the highest number of private alleles was 9 and 5 for ISM and TA, respectively. Percentage of shared alleles between the two ecotypes was 45%. This panel of markers is reasonably informative as the mean polymorphic information content for ISM and TA was 0.47±0.21, and 0.41±0.2. Similar average of observed heterozygosity was attained for both ecotypes. Conversely, averages of expected heterozygosity differed between two ecotypes, 0.52±0.23 vs. 0.45±0.21 for ISM and TA. 8 and 12 loci have significantly deviated from HWE of ISM and TA. Estimate of genetic distance was 0.2 and F<sub>ST</sub> index was 0.29. Results showed only 6% of genetic diversity is shared between these two ecotypes.展开更多
Cyanotoxins are distinctive molecules in Cyanobacteria whose evolutionary origin, radiation and ecological role are still controversial. The cyanobacterium Cylindrospermopsis raciborskii is alternately capable of prod...Cyanotoxins are distinctive molecules in Cyanobacteria whose evolutionary origin, radiation and ecological role are still controversial. The cyanobacterium Cylindrospermopsis raciborskii is alternately capable of producing two types of potent toxins, cylindrospermopsin (CYN) or saxitoxin and analogues (SAX). It has been proposed that this species spread to all continents early in its evolutionary history and biogeographical differences in toxin production are found between populations. Most reports indicate that American strains are able to produce SAX but not CYN, while Australian strains are described to produce CYN but not SAX. Here we describe the presence of three genes belonging to the cylindrospermopsin cluster (cyr), cyrA, cyrB and cyrC, in two SAX producing South American C. raciborskii strains, MVCC14 and MVCC19, which due to their differences in morphology, growth preferences, SAX production and genetic context are defined as different ecotypes. No CYN production was detected in either strain (by ELISA) after growth under nitrogen replete or nitrogen-free nutrient conditions. Phylogenetic analyses of cyrA, cyrB and cyrC partial sequences from both strains showed high similarity (>99%) with CYN genes belonging to C. raciborskii strains from Australia and Germany and to Aphanizomenon strains. This is the first report of the presence of cyr genes in strains known to produce only SAX.展开更多
Switchgrass(Panicum virgatum L.) is a warm-season rhizomatous perennial grass that can tolerate diverse abiotic stresses while yielding relatively high biomass, and is considered a leading biofuel feedstock for margin...Switchgrass(Panicum virgatum L.) is a warm-season rhizomatous perennial grass that can tolerate diverse abiotic stresses while yielding relatively high biomass, and is considered a leading biofuel feedstock for marginal lands. Nitrogen(N) is crucial for the growth and development of switchgrass, and its tolerance to low N supply and high N use efficiency are very important for its production under poor conditions. The large-scale planting of switchgrass on marginal lands could be an effective approach to solving the problem of feedstock supply for biomass energy. This study used a hydroponic experiment to evaluate the effect of N deficiency on switchgrass seedlings. Three N treatments(0, 0.15, and 1.50 mmol L-1Hoagland's solution)and six cultivars were used, three of each ecotype(upland and lowland). The results showed that biomass, leaf area, root surface area, net photosynthesis, and total chlorophyll content significantly decreased under low N treatments compared with those in full strength Hoagland's nutrient solution. However, once established, all plants survived extreme N stress(0 mmol L-1) and, to some extent, were productive. Cultivar Kanlow performed best of the six cultivars under stress. Significant interactions between stress treatment and cultivars showed that breeding for cultivars with high yield and superior performance under N deficiency is warranted. The lowland outperformed the upland ecotypes under stress, suggesting that lowland cultivars may survive and be productive under a wider range of stress conditions.However, given the better adaptability of lowland ecotypes to hydroponic cultivation, further study is needed.展开更多
Propamocarb(PM)residue in cucumber(Cucumis sativus L.)receives little attention.As is well known to all,high PM residue of cucumber could lead to increase in the violation rates of maximum residue limits and ultimatel...Propamocarb(PM)residue in cucumber(Cucumis sativus L.)receives little attention.As is well known to all,high PM residue of cucumber could lead to increase in the violation rates of maximum residue limits and ultimately cause harm to human health.Knowledge of PM residue could help cucumber breeders in developing cultivars with low PM residue and improving cucumber quality.In this study,32 representative cucumber accessions(26 breeding lines and six cultivars)from different regions of China were evaluated for their PM residue in fruit and leaf to provide meaning to the subjective rating,which was highly correlated with PM residual content of fruit(r=0.97)and leaf(r=0.94).In addition,PM residual content of North China ecotype was the highest and Pickling ecotype was the lowest in fruit and leaf of cucumber.The leaf had significantly higher(P<0.01)PM residual content than the fruit,and poor correlation between leaf and fruit was represented.This study verified PM residual relationship between fruit and leaf,and laid the foundation for further identification of germplasm resources and breeding of new varieties for low PM residue of cucumber.展开更多
Phosphorus is one of the most important nutrients required for plant growth and development. While substantial amounts of total phosphorus are present in many soil types, plants are unable to utilize some organic phos...Phosphorus is one of the most important nutrients required for plant growth and development. While substantial amounts of total phosphorus are present in many soil types, plants are unable to utilize some organic phosphorus sources. The main goal of this study was to characterize the spectrum of secreted plant proteins, organic acids and other metabolites that can potentially contribute to utilization of various phosphorus compounds. Our data indicate that the composition of extracellular proteins secreted by plant roots varies depending on the specific source of P in the growth medium. Furthermore, some root-secreted metabolites, such as citrate, appear to be specific to a subset of ecotypes, while tartrate, succinate and oxalate are secreted by a number of A. thaliana ecotypes. We observed secretion of phenolic compounds, such as tannins, and deoxycytidine derivatives. Taken together, while no single secreted polypeptide, organic acid or secondary metabolite can be pinpointed as specific to plant growth in particular phosphorus conditions, our data indicate that A. thaliana ecotypes differ in their physiological responses to the source of phosphorus in the growth medium. Overall, these results suggest that physiological changes in plant responses to nutrient limitation are modulated by interactions between soil phosphorus source and the specific genotype of Arabidopsis plants.展开更多
The morphology and anatomy of leaves of rheophytic and non-rheophytic types of Adenophora triphylla (Thunb.) ADC var. japonica (Regel) H. Hara were compared in order to clarify how leaf characteristics differ. Our res...The morphology and anatomy of leaves of rheophytic and non-rheophytic types of Adenophora triphylla (Thunb.) ADC var. japonica (Regel) H. Hara were compared in order to clarify how leaf characteristics differ. Our results revealed that the leaf of the rheophytic type of A. triphylla var. japonica was narrower than the leaf of the non-rheophytic type because of fewer cells that were also smaller. Moreover, surprisingly, the rheophytic ecotype of A. triphylla var. japonica was thinner than that of the non-rheophytic type, although the general tendency is that the rheophytic leaf is thicker than the closely related non-rheophytic species, suggesting that the rheophytic type of A. triphylla var. japonica adapts differently, as compared to other rheophytic plants, to solar radiation and evaporation.展开更多
The comparative morphology and anatomy of leaves between the coastal ecotype and the normal type of Adenophora triphylla (Thunb.) A.DC. var. japonica (Regel) H.Hara (Campanulaceae) were examined to clarify the differe...The comparative morphology and anatomy of leaves between the coastal ecotype and the normal type of Adenophora triphylla (Thunb.) A.DC. var. japonica (Regel) H.Hara (Campanulaceae) were examined to clarify the differences in morphological characters between the 2 groups. Morphological and anatomical analyses revealed that the coastal ecotype had a thicker leaf than the normal type, because of the increased size of epidermal and spongy cells. Thus, the main morphological change from the normal type into the coastal ecotype of A. triphylla var. japonica is the increase in leaf size, suggesting that the coastal ecotype may have evolved from the normal type via a heterochronic process.展开更多
We compared the leaf morphology and anatomy of the putative rheophytic ecotype of Viola mandshurica W. Becker var. ikedaeana (W. Becker ex Taken.) F. Maek. and its closely related variety, V. mandshurica var. mandshur...We compared the leaf morphology and anatomy of the putative rheophytic ecotype of Viola mandshurica W. Becker var. ikedaeana (W. Becker ex Taken.) F. Maek. and its closely related variety, V. mandshurica var. mandshurica. We showed that the leaf of the rheophytic ecotype of V. mandshurica var. ikedaeana was narrower than that of V. mandshurica var. mandshurica. Moreover, the leaf thickness and guard cell size of the rheophytic ecotype of V. mandshurica var. ikedaeana were significantly larger than those of V. mandshurica var. mandshurica. We further showed that leaves of the rheophytic ecotype of V. mandshurica var. ikedaeana contained fewer cells than did those of V. mandshurica var. mandshurica. Our results suggest that the narrower leaves of V. mandshurica var. ikedaeana are caused by a decrease in the number of cells. A narrower leaf may enable the rheophytic ecotype of V. mandshurica var. ikedaeana to resist the strong flow of water that occurs after heavy rainfall, while a thicker leaf may enhance tolerance to desiccation and high- intensity light.展开更多
Grass pea (Lathyrus sativus L.) has great agronomic potential as grain and forage legume, and presently is con-sidered as a model crop for sustainable agriculture. However, the development into an important food legum...Grass pea (Lathyrus sativus L.) has great agronomic potential as grain and forage legume, and presently is con-sidered as a model crop for sustainable agriculture. However, the development into an important food legume has been hin- dered by the presence of the neurotoxic amino acid β-N-Oxalyl-α, β-diaminopropionic acid (β-ODAP). Recent studies reported that homoarginine (Har) can counteract this toxic action. This research was undertaken to shed light on the variation of Har amount within grass pea. The influence of the environment and of the year-to-year variation of cli- matic conditions was also investigated. Seven Italian grass pea ecotypes were evaluated for two subsequent growing seasons in two locations of southern Italy. In contrast with previous studies collected data evidenced a significant variation of Har amount among the tested ecotypes. Moreover, a significant positive correlation between Har and ODAP level was observed. The effect of year-to-year variation of temperature and rainfall quantity is also discussed.展开更多
The objective of the present study was to determine the optimum sowing time of three quinoa ecotypes (Altipllano, sea level, and valley) for high seed yields in south Kanto, Japan. Pot experiments were conducted in th...The objective of the present study was to determine the optimum sowing time of three quinoa ecotypes (Altipllano, sea level, and valley) for high seed yields in south Kanto, Japan. Pot experiments were conducted in the experimental field at Nihon University during 2011, 2012, 2013, and 2014. In this experiment, the following quinoa varieties were used NL-6, Baer Cajon and Cauquenes (sea-level type), Amarilla de Marangani, Blanca de Junin, CICA-127, ECU-420, ECU-525, Ingapirica, and Narino (valley type), 94R and Isluga (Altiplano type). The quinoa seeds were sown on March 29, June 17 and September 22, 2011;March 27, June 17 and August 28, 2012;March 26, June 15 and 5 September 5, 2013;and March 27, June 17 and August 28, 2014. When the sea-level type and Altiplano type seeds were sowed from March to September, the seeds could be gained in all sowing plots. However, the seed weights of all varieties were the highest in the sowing plots of March. And the seed weights in the sowing plot of March were significantly higher than that in the other sowing plots. The sea-level type and Altiplano type quinoa had almost the same seed growth reaction for day length and day temperature. Thus, to gain a high seed yield of the sea-level and Altiplano type quinoa, March was the optimum sowing time in south Kanto, Japan. When the valley-type seeds were sowed from March to June, the seeds could not be gained, except in 2012. In 2012, the seed weights and seed numbers in sowing plots of March and June were significantly lower than those in the sowing plot of September. Thus, to obtain a high seed yield of the valley type quinoa, the optimum sowing time in south Kanto, Japan was from August to September.展开更多
Clonal organisms are particularly useful to investigate the contribution of epigenetics to phenotypic plasticity,because confounding effects of genetic variation are negligible.In the last decade,the apomictic parthen...Clonal organisms are particularly useful to investigate the contribution of epigenetics to phenotypic plasticity,because confounding effects of genetic variation are negligible.In the last decade,the apomictic parthenogenetic marbled crayfish,Procambarus virginalis,has been developed as a model to investigate the relationships between phenotypic plasticity and genetic and epigenetic diversity in detail.This crayfish originated about 30 years ago by autotriploidy from a single slough crayfish Procambarus fallax.As the result of human releases and active spreading,marbled crayfish has established numerous populations in very diverse habitats in 22 countries from the tropics to cold temperate regions.Studies in the laboratory and field revealed considerable plasticity in coloration,spination,morphometric parameters,growth,food preference,population structure,trophic position,and niche width.Illumina and PacBio whole-genome sequencing of marbled crayfish from representatives of 19 populations in Europe and Madagascar demonstrated extremely low genetic diversity within and among populations,indicating that the observed phenotypic diversity and ability to live in strikingly different environments are not due to adaptation by selection on genetic variation.In contrast,considerable differences were found between populations in the DNA methylation patterns of hundreds of genes,suggesting that the environmentally induced phenotypic plasticity is mediated by epigenetic mechanisms and corresponding changes in gene expression.Specific DNA methylation fingerprints persisted in local populations over successive years indicating the existence of epigenetic ecotypes,but there is presently no information as to whether these epigenetic signatures are transgenerationally inherited or established anew in each generation and whether the recorded phenotypic plasticity is adaptive or nonadaptive.展开更多
Aims Positive plant interactions can promote higher species density of beneficiary species in deserts.However,there is limited evidence examining the trait sets of seeds from beneficiary species.in this study,we exami...Aims Positive plant interactions can promote higher species density of beneficiary species in deserts.However,there is limited evidence examining the trait sets of seeds from beneficiary species.in this study,we examined the hypothesis that shrubs(benefactors)influ-ence the germination of desert annuals(beneficiaries)and promote ecotypic differentiation by generating distinct microhabitats through abiotic stress amelioration.The following predictions were tested using growth chambers and field-collected seeds:(i)seed mass and viability will be greater and less variable for seeds collected from within shrub understory relative to seeds from open microhabitats,(ii)germination of seeds from shrub and open microhabitats will be greatest under simulated home(source)conditions,(iii)seeds from the shrub microhabitat will adaptively accelerate their germination rate when germinated in simulated home(source)microhabitats relative to their simulated away(reciprocal)microhabitat.Methods Seeds and their associated maternal plants were collected from four annual species found within a shrub understory(Larrea triden-tata)and open microhabitats in the Mojave Desert of California(35.30ºN,117.26ºW,793 m.a.s.l.),and then reciprocally germi-nated in growth chambers simulating both microclimatic conditions.Cumulative germination and germination rate was measured every 4-5 days for 42 days.Important Findings There was no significant difference in the mean or coefficient of variation for seed mass and viability between the shrub and open microhabitats.The source of the seeds did not significantly impact the cumulative germination,and there was no accelerated rate of germination within potential species ecotypes thereby suggesting no ecotypic differentiation.Cumulative germination was signifi-cantly higher within the shrub-simulated microhabitat for three out of the four species examined.Cumulative germination and germina-tion rate were significantly different between species.Hence,shrubs influence the germination of desert annuals,and the outcome of this interaction is species specific,but shrub microhabitats do not nec-essarily alter the more conserved seed biology traits.Future studies should examine the influence of gene flow on beneficiary adapta-tion and the influence of species-specificity on beneficiary species response to facilitation.展开更多
Drought resistance is required in rice breeding to address the challenge of frequent droughts . However, the evolutionary mechanism of rice drought resistance is not fully understood. We investigated the genetic diffe...Drought resistance is required in rice breeding to address the challenge of frequent droughts . However, the evolutionary mechanism of rice drought resistance is not fully understood. We investigated the genetic differentiation between upland and lowland rice domesticated in agro-ecosystems with contrasting water-soil conditions using genome-wide SNPs. We estimated morphological differences among upland and lowland rice in drought resistance and productivity through common garden experiments. Upland rice had better drought resistance but poorer productivity. The negative correlations between traits of drought resistance and productivity are attributed to the underlying genetic trade-offs through tight linkages (e.g., DCA1 and OsCesA7) or pleiotropic effects (e.g., LAX1). The genetic trade-offs are comm on and greatly shape the evolutio n of drought resista nee in upland rice . In genomic regions associated with both productivity and drought resistance, signs of balancing selection were detected in upland rice, while signs of directional selection were detected in lowland rice, potentially contributing to their adaptive differentiation. Signs of balancing selection in upland rice resulted from bi-directional selection during its domestication in drought-prone upland agro-ecosystems.Using genome-wide association analysis, we ide ntified several valuable quantitative trait loci associated with drought resista nee, for which highly differentiated genes should be considered candidates. Bi-directional selection breaking tight linkages by accumulating recombination events would be applicable in breeding water-saving and droughtresistance rice.展开更多
文摘In order to better understand the cultural route, biochemical and nutritional composition of two ecotypes of fonio, a study was carried out in village of Tambananing located approximately 7 km from Sédhiou. The objective of studies was to determine nutritional composition of two ecotypes of fonio: the first called momo in short-cycle mandinka (75 - 90 days) and the other called medium-cycle dibong (90 - 110 days). For this, samples of two ecotypes were collected in an experimental field which was split into two equal parts, one sown with the momo ecotype and the other with the dibong ecotype. The nutritional composition (sugars, fats, proteins, minerals, ash, etc.) and the physicochemical properties (pH, humidity, water activity, color, etc.) of fonio’s were determined by appropriate physicochemical methods. The two ecotypes exhibited quite similar physicochemical properties. The levels of biochemical compounds were relatively close with protein contents of 7.05 ± 0.06 mg/100g for the momo ecotype and of 8.02 ± 0.04 mg/100g for the dibong ecotype, in carbohydrates (76.37 ± 1.2 mg/100g for momo and 78.7 ± 1.5 mg/100g for dibong) and in fat (2.92 ± 0.05 mg/100g for momo and 3.14 ± 0.004 mg/100g for dibong). Identical mineral element contents were found except for iron, an element for which the contents were 10.80 ± 0.008 mg/100g for the momo ecotype and 99.59 ± 0.005 mg/100g for the dibong ecotype. Thus, two ecotypes of fonio present a fairly interesting nutritional composition and their consumption deserves to be popularized and could contribute effectively to fight against the problems of malnutrition of certain vulnerable groups.
文摘This study was conducted from June 2021 to January 2023 to assess the genetic diversity of giant African snails in the western highlands of Cameroon. A total of 652 snails were randomly collected from the wild in three localities in the western highlands (Bafang, Bafoussam, and Santchou). The study revealed significant variations in morphobiometric characteristics both between species and localities. The predominant shell coloration was brownish with yellow zigzag stripes (65%), while the dominant coloration for shell openings was whitish (48%). Regarding foot coloration, both brown with spotted black and black with spotted brown colorations were dominant (29%). The highest recorded live weight of snails (39.33 ± 34) was found in the species Archachatina marginata. In terms of length measurements (in mm), the length of the right and left sides of the shell was higher in the A. fulica species (49.8 ± 19.7 mm and 40.07 ± 18 mm, respectively). Bafang exhibited the highest values for shell length (56 ± 11 mm) and shell width (46.52 ± 11.46 mm). A. fulica recorded the highest shell length (81.5 ± 27 mm), while A. marginata recorded the highest shell width (49.6 ± 12.1 mm), with the highest values observed in A. fulica from fulica having a slightly higher aperture width value (30 ± 10 mm) compared to A. marginata, while A. marginata had the highest value for aperture length measurement (54.5 ± 12 mm). A. fulica also exhibited the highest values for the length from apex to the first whorl and the length from left to right of the first whorl (43.2 ± 18 mm and 39 ± 19.8 mm, respectively). Strong and positive correlations were observed between the live weight of snails and body measurements regardless of species, except for the number of whorls, which showed very weak or negative correlations with other body measurements. The results of Hierarchical Cluster Analysis (HCA) revealed three distinct snail population types. These findings provide valuable insights into the phenotypic diversity of edible land snails in the western highlands of Cameroon and can be considered in improvement and conservation programs aimed at enhancing snail meat yield.
文摘The basin of Lake Titicaca is a faba bean-producing microregion of Bolivia where the crop is destined for export. The most commonly cultivated ecotypes “Gigante de Copacabana” and “Usnayo” are affected by diseases that can cause production losses. The aims of the present work were to identify the causal agents of leaf spot affecting these ecotypes, to record disease intensity levels, and to estimate their effect on production. In 2004 and 2005, leaflet, stem and pod samples were taken from faba bean plants with leaf spot growing in the Lake Titicaca area, and from plants in an experimental plot established to determine the effect of five different treatments on production and disease intensity: T1 = Control;T2 = seed treatment with Trichoderma sp. + alternate foliar spraying with benomyl and mancozeb;T3 = seed treatment with fludioxanil/metalaxyl M + alternate foliar spraying with benomyl and mancozeb;T4 = foliar spraying with Trichoderma sp.;T5 = alternate foliar spraying with cymoxanyl and mancozeb-chlorothalonil. Microscopic analysis of the samples revealed the presence of new fungal pathogens for faba beans in Bolivia (Cladosporium sp., and Lepthosphaerulina sp.) as well as emerging fungal pathogens (Botrytis cinerea, B. fabae, Ascochyta fabae, Alternaria sp. and Cercospora sp.). None of the treatments affected the disease progression curve (DPC) for incidence, although effects were seen with respect to disease severity. The seed + foliar treatments (T2 and T3) were more effective at controlling disease than leaf treatments on their own (T4 and T5). Modelling analysis showed faba bean leaf spot disease to be moderately destructive. Compared to chemical treatments, biocontrol with Trichoderma spp. preliminary was found to provide good control of the disease. Losses due to leaf spot disease of 36% were recorded, and a strong correlation detected between yield and disease severity.
文摘The roots and leaves of four reed ecotypes (Phragmites communis Trinius) growing in the desertregions of northwest China were determined for the levels of abscisic acid (ABA) and cytokinins [isopenteny-ladenosine (iPA) and zeatin riboside (ZR) ] using an
文摘To determine the size and the density of stomata among different environments, we conducted anatomical analyses using Aster hispidus var. hispidus (open field), As. hispidus var. leptocladus (serpentine soil), and As. hispidus var. insularis (coastal). The stomatal size was not significantly different among these ecotypes but the density of stomata in the serpentine and coastal ecotypes was significantly lower than that of As. hispidus var. hispidus, which suggests that these ecotypes have experienced selection that reduced the density of stomata for adaptation to the dry conditions of serpentine and coastal areas.
基金National Scientific Foundation of China(31470404 and 31070228).
文摘Aims The two coexisting Leymus chinensis ecotypes exhibit remarkable divergences in adaptive strategies under drought and salinity in semi-humid meadows and semi-arid steppes.In order to detect the major genetic and environmental factors dominating the intraspecific phenotype variations and ecotype formation,the questions regarding the two distinct phenotypic forms(ecotypes)in L.chin-ensis were addressed:(i)did environments drive the L.chinensis ecotype formation?(ii)was there a molecular basis for the morphological divergence between the two ecotypes?(iii)which driving force dominated the intraspecies divergence,divergent natural selection,genetic drift or stabilizing selection?Methods We applied a series experiments on demographical,morphological and physiological traits of two Leymus chinensis ecotypes with gray green(GG)and yellow green(YG)leaf color in nine wild sites along a longitudinal gradient from 114°to 124°E in northeast China.The environmental data including mean annual precipitation,mean annual temperature,elevation and soil properties were collected.We compared the differences of morphological,physiological and genetic differentiations between the two ecotypes.Important FindingsThe GG type exhibited stronger fitness than YG type from the population densities,morphological traits(e.g.shoot height,leaf area,leaf and seed weights et al.),leaf mass per area(LMA)and physiological traits[relative water content(RWC),proline,soluble sugar contents].Most of above phenotypes(e.g.total shoot densities,spike length et al.)were significantly correlated with mean annual precipitation,mean annual temperature and soil water content(SWC),rarely a correlated with soil pH and soil nutrient.Transplanted populations showed convergence trend by their leaf chlorophyll contents and osmotic adjustments(proline and soluble sugar contents)in the greenhouse,but still exhibited their divergences between two ecotypes in the outdoor transplantation,suggesting that whether L.chinensis ecotype differentiated could be largely affected by the environmental conditions.Furthermore,by the comparison result of quantitative genetic variation(Q_(ST))values from phenotypes with theoretical neutral genetic differentiation(F_(ST)),differentiation in phenotypic traits greatly surpassed neutral predictions,implying that directional natural selection played a crucial role in L.chinen-sis ecotype differentiation.In addition,microsatellite analysis from Neighbor-joining tree and Bayesian assignment generated into two groups according to ecotypes,indicating molecular genetic differentiation also propelled the two ecotypes divergence.We conclude that L.chinensis population variations were driven by combing divergent natural selection(precipitation,temperature and SWCs)along the large-scale gradient and significantly intrinsic genetic differentiation.
文摘We investigated whether plant ecotype might affect aphid performance and behavioi. The probing behaviors of the polyphagous aphid Myzus persicae and the oligophagous aphid Brevicoryne brassicae on two ecotypes of Arabidopsis thaliana, WS and Col-0 were recorded using the direct current electrical penetration graph method (DC-EPG). Myzus persicae displayed a significant preference for the WS ecotype but was not greatly disturbed on Col-0, while B. brassicae discriminated between the two A. thaliana ecotypes, feeding less on WS than on Col-0. A Principal Component Analysis of aphid probing behavior data recorded on Col-0 and WS ecotypes showed that the one of M. persicae was positively correlated with the phloem ingestion phases while the one of B. brassicae was more related to nonfeeding phase. The survival of the aphid species was followed during early larval stages on the two ecotypes and a significantly higher mortality was observed of B. brassicae neonates compared to M. persicae. Both reared on WS. Moreover, transcriptomic analysis of non infested plant leaves from both ecotypes was monitored and underlined constitutive differences between Col-0 and WS gene expression that might explain the different aphid behaviors. Among a unigene set comprising 39 042 sequences for A. thaliana, 6% were differently expressed affecting, for example, the secondary metabolites and cell wall pathways: two third upregulated in WS and one third upregulated in Col-0. Thus, the "ecotype” variable should be taken into account when setting up a plant-insect experimental research.
文摘Genetic diversity of two chicken ecotypes from Ismailia-Egypt (ISM) and Taif-Saudi Arabia (TA) was evaluated using 39 microsatellites. DNA was extracted from blood of 25 chickens/ecotype. The number of alleles was 157 and 138, the number of alleles/locus averaged 4.2±2.2 and 3.6±1.6, and the highest number of private alleles was 9 and 5 for ISM and TA, respectively. Percentage of shared alleles between the two ecotypes was 45%. This panel of markers is reasonably informative as the mean polymorphic information content for ISM and TA was 0.47±0.21, and 0.41±0.2. Similar average of observed heterozygosity was attained for both ecotypes. Conversely, averages of expected heterozygosity differed between two ecotypes, 0.52±0.23 vs. 0.45±0.21 for ISM and TA. 8 and 12 loci have significantly deviated from HWE of ISM and TA. Estimate of genetic distance was 0.2 and F<sub>ST</sub> index was 0.29. Results showed only 6% of genetic diversity is shared between these two ecotypes.
文摘Cyanotoxins are distinctive molecules in Cyanobacteria whose evolutionary origin, radiation and ecological role are still controversial. The cyanobacterium Cylindrospermopsis raciborskii is alternately capable of producing two types of potent toxins, cylindrospermopsin (CYN) or saxitoxin and analogues (SAX). It has been proposed that this species spread to all continents early in its evolutionary history and biogeographical differences in toxin production are found between populations. Most reports indicate that American strains are able to produce SAX but not CYN, while Australian strains are described to produce CYN but not SAX. Here we describe the presence of three genes belonging to the cylindrospermopsin cluster (cyr), cyrA, cyrB and cyrC, in two SAX producing South American C. raciborskii strains, MVCC14 and MVCC19, which due to their differences in morphology, growth preferences, SAX production and genetic context are defined as different ecotypes. No CYN production was detected in either strain (by ELISA) after growth under nitrogen replete or nitrogen-free nutrient conditions. Phylogenetic analyses of cyrA, cyrB and cyrC partial sequences from both strains showed high similarity (>99%) with CYN genes belonging to C. raciborskii strains from Australia and Germany and to Aphanizomenon strains. This is the first report of the presence of cyr genes in strains known to produce only SAX.
基金supported by the project of Scientific and Technological Innovation Ability Construction funded by Beijing Academy of Agriculture and Forestry Sciences(KJCX201102005,KJCX201101003,and KJCX201103001)
文摘Switchgrass(Panicum virgatum L.) is a warm-season rhizomatous perennial grass that can tolerate diverse abiotic stresses while yielding relatively high biomass, and is considered a leading biofuel feedstock for marginal lands. Nitrogen(N) is crucial for the growth and development of switchgrass, and its tolerance to low N supply and high N use efficiency are very important for its production under poor conditions. The large-scale planting of switchgrass on marginal lands could be an effective approach to solving the problem of feedstock supply for biomass energy. This study used a hydroponic experiment to evaluate the effect of N deficiency on switchgrass seedlings. Three N treatments(0, 0.15, and 1.50 mmol L-1Hoagland's solution)and six cultivars were used, three of each ecotype(upland and lowland). The results showed that biomass, leaf area, root surface area, net photosynthesis, and total chlorophyll content significantly decreased under low N treatments compared with those in full strength Hoagland's nutrient solution. However, once established, all plants survived extreme N stress(0 mmol L-1) and, to some extent, were productive. Cultivar Kanlow performed best of the six cultivars under stress. Significant interactions between stress treatment and cultivars showed that breeding for cultivars with high yield and superior performance under N deficiency is warranted. The lowland outperformed the upland ecotypes under stress, suggesting that lowland cultivars may survive and be productive under a wider range of stress conditions.However, given the better adaptability of lowland ecotypes to hydroponic cultivation, further study is needed.
基金Supported by the National Natural Science Foundation of China(31272158)863 Program of the National Science and Technology of China(2012AA100105)
文摘Propamocarb(PM)residue in cucumber(Cucumis sativus L.)receives little attention.As is well known to all,high PM residue of cucumber could lead to increase in the violation rates of maximum residue limits and ultimately cause harm to human health.Knowledge of PM residue could help cucumber breeders in developing cultivars with low PM residue and improving cucumber quality.In this study,32 representative cucumber accessions(26 breeding lines and six cultivars)from different regions of China were evaluated for their PM residue in fruit and leaf to provide meaning to the subjective rating,which was highly correlated with PM residual content of fruit(r=0.97)and leaf(r=0.94).In addition,PM residual content of North China ecotype was the highest and Pickling ecotype was the lowest in fruit and leaf of cucumber.The leaf had significantly higher(P<0.01)PM residual content than the fruit,and poor correlation between leaf and fruit was represented.This study verified PM residual relationship between fruit and leaf,and laid the foundation for further identification of germplasm resources and breeding of new varieties for low PM residue of cucumber.
文摘Phosphorus is one of the most important nutrients required for plant growth and development. While substantial amounts of total phosphorus are present in many soil types, plants are unable to utilize some organic phosphorus sources. The main goal of this study was to characterize the spectrum of secreted plant proteins, organic acids and other metabolites that can potentially contribute to utilization of various phosphorus compounds. Our data indicate that the composition of extracellular proteins secreted by plant roots varies depending on the specific source of P in the growth medium. Furthermore, some root-secreted metabolites, such as citrate, appear to be specific to a subset of ecotypes, while tartrate, succinate and oxalate are secreted by a number of A. thaliana ecotypes. We observed secretion of phenolic compounds, such as tannins, and deoxycytidine derivatives. Taken together, while no single secreted polypeptide, organic acid or secondary metabolite can be pinpointed as specific to plant growth in particular phosphorus conditions, our data indicate that A. thaliana ecotypes differ in their physiological responses to the source of phosphorus in the growth medium. Overall, these results suggest that physiological changes in plant responses to nutrient limitation are modulated by interactions between soil phosphorus source and the specific genotype of Arabidopsis plants.
文摘The morphology and anatomy of leaves of rheophytic and non-rheophytic types of Adenophora triphylla (Thunb.) ADC var. japonica (Regel) H. Hara were compared in order to clarify how leaf characteristics differ. Our results revealed that the leaf of the rheophytic type of A. triphylla var. japonica was narrower than the leaf of the non-rheophytic type because of fewer cells that were also smaller. Moreover, surprisingly, the rheophytic ecotype of A. triphylla var. japonica was thinner than that of the non-rheophytic type, although the general tendency is that the rheophytic leaf is thicker than the closely related non-rheophytic species, suggesting that the rheophytic type of A. triphylla var. japonica adapts differently, as compared to other rheophytic plants, to solar radiation and evaporation.
文摘The comparative morphology and anatomy of leaves between the coastal ecotype and the normal type of Adenophora triphylla (Thunb.) A.DC. var. japonica (Regel) H.Hara (Campanulaceae) were examined to clarify the differences in morphological characters between the 2 groups. Morphological and anatomical analyses revealed that the coastal ecotype had a thicker leaf than the normal type, because of the increased size of epidermal and spongy cells. Thus, the main morphological change from the normal type into the coastal ecotype of A. triphylla var. japonica is the increase in leaf size, suggesting that the coastal ecotype may have evolved from the normal type via a heterochronic process.
文摘We compared the leaf morphology and anatomy of the putative rheophytic ecotype of Viola mandshurica W. Becker var. ikedaeana (W. Becker ex Taken.) F. Maek. and its closely related variety, V. mandshurica var. mandshurica. We showed that the leaf of the rheophytic ecotype of V. mandshurica var. ikedaeana was narrower than that of V. mandshurica var. mandshurica. Moreover, the leaf thickness and guard cell size of the rheophytic ecotype of V. mandshurica var. ikedaeana were significantly larger than those of V. mandshurica var. mandshurica. We further showed that leaves of the rheophytic ecotype of V. mandshurica var. ikedaeana contained fewer cells than did those of V. mandshurica var. mandshurica. Our results suggest that the narrower leaves of V. mandshurica var. ikedaeana are caused by a decrease in the number of cells. A narrower leaf may enable the rheophytic ecotype of V. mandshurica var. ikedaeana to resist the strong flow of water that occurs after heavy rainfall, while a thicker leaf may enhance tolerance to desiccation and high- intensity light.
文摘Grass pea (Lathyrus sativus L.) has great agronomic potential as grain and forage legume, and presently is con-sidered as a model crop for sustainable agriculture. However, the development into an important food legume has been hin- dered by the presence of the neurotoxic amino acid β-N-Oxalyl-α, β-diaminopropionic acid (β-ODAP). Recent studies reported that homoarginine (Har) can counteract this toxic action. This research was undertaken to shed light on the variation of Har amount within grass pea. The influence of the environment and of the year-to-year variation of cli- matic conditions was also investigated. Seven Italian grass pea ecotypes were evaluated for two subsequent growing seasons in two locations of southern Italy. In contrast with previous studies collected data evidenced a significant variation of Har amount among the tested ecotypes. Moreover, a significant positive correlation between Har and ODAP level was observed. The effect of year-to-year variation of temperature and rainfall quantity is also discussed.
文摘The objective of the present study was to determine the optimum sowing time of three quinoa ecotypes (Altipllano, sea level, and valley) for high seed yields in south Kanto, Japan. Pot experiments were conducted in the experimental field at Nihon University during 2011, 2012, 2013, and 2014. In this experiment, the following quinoa varieties were used NL-6, Baer Cajon and Cauquenes (sea-level type), Amarilla de Marangani, Blanca de Junin, CICA-127, ECU-420, ECU-525, Ingapirica, and Narino (valley type), 94R and Isluga (Altiplano type). The quinoa seeds were sown on March 29, June 17 and September 22, 2011;March 27, June 17 and August 28, 2012;March 26, June 15 and 5 September 5, 2013;and March 27, June 17 and August 28, 2014. When the sea-level type and Altiplano type seeds were sowed from March to September, the seeds could be gained in all sowing plots. However, the seed weights of all varieties were the highest in the sowing plots of March. And the seed weights in the sowing plot of March were significantly higher than that in the other sowing plots. The sea-level type and Altiplano type quinoa had almost the same seed growth reaction for day length and day temperature. Thus, to gain a high seed yield of the sea-level and Altiplano type quinoa, March was the optimum sowing time in south Kanto, Japan. When the valley-type seeds were sowed from March to June, the seeds could not be gained, except in 2012. In 2012, the seed weights and seed numbers in sowing plots of March and June were significantly lower than those in the sowing plot of September. Thus, to obtain a high seed yield of the valley type quinoa, the optimum sowing time in south Kanto, Japan was from August to September.
文摘Clonal organisms are particularly useful to investigate the contribution of epigenetics to phenotypic plasticity,because confounding effects of genetic variation are negligible.In the last decade,the apomictic parthenogenetic marbled crayfish,Procambarus virginalis,has been developed as a model to investigate the relationships between phenotypic plasticity and genetic and epigenetic diversity in detail.This crayfish originated about 30 years ago by autotriploidy from a single slough crayfish Procambarus fallax.As the result of human releases and active spreading,marbled crayfish has established numerous populations in very diverse habitats in 22 countries from the tropics to cold temperate regions.Studies in the laboratory and field revealed considerable plasticity in coloration,spination,morphometric parameters,growth,food preference,population structure,trophic position,and niche width.Illumina and PacBio whole-genome sequencing of marbled crayfish from representatives of 19 populations in Europe and Madagascar demonstrated extremely low genetic diversity within and among populations,indicating that the observed phenotypic diversity and ability to live in strikingly different environments are not due to adaptation by selection on genetic variation.In contrast,considerable differences were found between populations in the DNA methylation patterns of hundreds of genes,suggesting that the environmentally induced phenotypic plasticity is mediated by epigenetic mechanisms and corresponding changes in gene expression.Specific DNA methylation fingerprints persisted in local populations over successive years indicating the existence of epigenetic ecotypes,but there is presently no information as to whether these epigenetic signatures are transgenerationally inherited or established anew in each generation and whether the recorded phenotypic plasticity is adaptive or nonadaptive.
文摘Aims Positive plant interactions can promote higher species density of beneficiary species in deserts.However,there is limited evidence examining the trait sets of seeds from beneficiary species.in this study,we examined the hypothesis that shrubs(benefactors)influ-ence the germination of desert annuals(beneficiaries)and promote ecotypic differentiation by generating distinct microhabitats through abiotic stress amelioration.The following predictions were tested using growth chambers and field-collected seeds:(i)seed mass and viability will be greater and less variable for seeds collected from within shrub understory relative to seeds from open microhabitats,(ii)germination of seeds from shrub and open microhabitats will be greatest under simulated home(source)conditions,(iii)seeds from the shrub microhabitat will adaptively accelerate their germination rate when germinated in simulated home(source)microhabitats relative to their simulated away(reciprocal)microhabitat.Methods Seeds and their associated maternal plants were collected from four annual species found within a shrub understory(Larrea triden-tata)and open microhabitats in the Mojave Desert of California(35.30ºN,117.26ºW,793 m.a.s.l.),and then reciprocally germi-nated in growth chambers simulating both microclimatic conditions.Cumulative germination and germination rate was measured every 4-5 days for 42 days.Important Findings There was no significant difference in the mean or coefficient of variation for seed mass and viability between the shrub and open microhabitats.The source of the seeds did not significantly impact the cumulative germination,and there was no accelerated rate of germination within potential species ecotypes thereby suggesting no ecotypic differentiation.Cumulative germination was signifi-cantly higher within the shrub-simulated microhabitat for three out of the four species examined.Cumulative germination and germina-tion rate were significantly different between species.Hence,shrubs influence the germination of desert annuals,and the outcome of this interaction is species specific,but shrub microhabitats do not nec-essarily alter the more conserved seed biology traits.Future studies should examine the influence of gene flow on beneficiary adapta-tion and the influence of species-specificity on beneficiary species response to facilitation.
基金the National Key R&D Programe of China (grant no. 2017YFD0300100)Shanghai Agriculture Applied Technology Development Program, China (grant no. G2016060107)+4 种基金Shanghai Natural Science Foundation (17ZR1425500)National High-Tech Research and Development Program of China (863 Plan (grant no.2014AA10A603)Shan ghai Agriculture Applied Tech no logy Developme nt Program, China (grant no. 2017-02-08-00-08-F00071)National Natural Science Foundation of China (grant no. 31501270)Shared Platform of Crop Germplasm Resources in Shanghai (18DZ2293700).
文摘Drought resistance is required in rice breeding to address the challenge of frequent droughts . However, the evolutionary mechanism of rice drought resistance is not fully understood. We investigated the genetic differentiation between upland and lowland rice domesticated in agro-ecosystems with contrasting water-soil conditions using genome-wide SNPs. We estimated morphological differences among upland and lowland rice in drought resistance and productivity through common garden experiments. Upland rice had better drought resistance but poorer productivity. The negative correlations between traits of drought resistance and productivity are attributed to the underlying genetic trade-offs through tight linkages (e.g., DCA1 and OsCesA7) or pleiotropic effects (e.g., LAX1). The genetic trade-offs are comm on and greatly shape the evolutio n of drought resista nee in upland rice . In genomic regions associated with both productivity and drought resistance, signs of balancing selection were detected in upland rice, while signs of directional selection were detected in lowland rice, potentially contributing to their adaptive differentiation. Signs of balancing selection in upland rice resulted from bi-directional selection during its domestication in drought-prone upland agro-ecosystems.Using genome-wide association analysis, we ide ntified several valuable quantitative trait loci associated with drought resista nee, for which highly differentiated genes should be considered candidates. Bi-directional selection breaking tight linkages by accumulating recombination events would be applicable in breeding water-saving and droughtresistance rice.
