Genetic and epigenetic changes during the invasion of a cosmopolitan species (Phragmites australis).

Genetic diversity defines the evolutionary potential of a species, yet mounting evidence suggests that epigenetic diversity could also contribute to adaptation. Elucidating the complex interplay between genetic and epigenetic variation in wild populations remains a challenge for evolutionary biologists, and the intriguing possibility that epigenetic diversity could compensate for the loss of genetic diversity is one aspect that remains basically unexplored in wild plants. This hypothesis is addressed in this paper by comparing the extent and patterns of genetic and epigenetic diversity of phylogenetically closely related but ecologically disparate species. Seven pairs of congeneric species from Cazorla mountains in south-eastern Spain were studied, each pair consisting of one endemic, restricted-range species associated to stressful environments, and one widespread species occupying more favourable habitats. The prediction was tested that endemic species should have lower genetic diversity due to population fragmentation, and higher epigenetic diversity induced by environmental stress, than their widespread congeners. Genetic (DNA sequence variants) and epigenetic (DNA cytosine methylation variants) diversities and their possible co-variation were assessed in three populations of each focal species using amplified fragment length polymorphism (AFLP) and methylation-sensitive AFLP (MSAP). All species and populations exhibited moderate to high levels of genetic polymorphism irrespective of their ecological characteristics. Epigenetic diversity was greater than genetic diversity in all cases. Only in endemic species were the two variables positively related, but the difference between epigenetic and genetic diversity was greater at populations with low genetic polymorphism. Results revealed that the relationship between genetic and epigenetic diversity can be more complex than envisaged by the simple hypothesis addressed in this study, and highlight the need of additional research on the actual role of epigenetic variation as a source of phenotypic diversity before a realistic understanding of the evolutionary relevance of epigenetic phenomena in plant adaptation can be achieved.

Epigenetic variation may contribute to traits that are important in domestication, but how patterns of genetic and epigenetic variation differ between cultivated and wild plants remains poorly understood. In particular, we know little about how selection may shape epigenetic variation in natural and cultivated populations. In this study, we investigated 11 natural populations and 6 major cultivated populations using amplified fragment length polymorphism (AFLP) and methylation-sensitive AFLP (MS-AFLP or MSAP) markers to identify patterns of genetic and epigenetic diversity among Corydalis yanhusuo populations. We further explored correlations among genetic, epigenetic, alkaloidal, and climatic factors in natural and cultivated C. yanhusuo. We found support for a single origin for all cultivated populations, from a natural population which was differentiated from the other natural populations. The magnitude of F ST based on AFLP was significantly correlated with that for MSAP in pairwise comparisons in both natural and cultivated populations, suggesting a relationship between genetic and epigenetic variation in C. yanhusuo. This relationship was further supported by dbRDA (distance-based redundancy analyses) where some of the epigenetic variation could be explained by genetic variation in natural and cultivated populations. Genetic variation was slightly higher in natural than cultivated populations, and exceeded epigenetic variation in both types of populations. However, epigenetic differentiation exceeded that of genetic differentiation among cultivated populations, while the reverse was observed among natural populations. The differences between wild and cultivated plants may be partly due to processes inherent to cultivation and in particular the differences in mode of reproduction. The importance of epigenetic compared to genetic modifications is thought to vary depending on reproductive strategies, and C. yanhusuo usually reproduces sexually in natural environments, while the cultivated C. yanhusuo are propagated clonally. In addition, alkaloid content of C. yanhusuo varied across cultivated populations, and alkaloid content was significantly correlated to climatic variation, but also to genetic (6.89%) and even more so to epigenetic (14.09%) variation in cultivated populations. Our study demonstrates that epigenetic variation could be important in cultivation of C. yanhusuo and serve as a source of variation for response to environmental conditions.

Maize is an important crop species that has been subjected to intensive breeding programs. Understanding the genetic diversity in maize is thus vital for crop improvement and breeding studies. We performed four different multi-allele detecting marker systems amplified fragment length polymorphism (AFLP), sequence-specific amplified polymorphism (SSAP), methylation-sensitive amplified polymorphism (MSAP), and transposon display methylation amplified polymorphism (TD-MSAP) to analyze genetic and epigenetic variation and diversity among dent, waxy, and sweet corn. The (epi) genetic diversity, (epi) genetic distance, gene flow, genetic frequency, cluster analysis, PCoA, and AMOVA analysis were calculated. Cultivar differentiation is well-established in maize, and the results suggest that not only genetic but also epigenetic variation is responsible for the differences obtained in maize cultivars. Estimates of genetic relationship were significantly correlated between the AFLP, SSAP, and MSAP datasets. The current study is the first report on the systematic comparison of TD-MSAP with the other marker systems. The genetic variation detected by TD-MSAP was higher than that calculated by AFLP, SSAP, and MSAP but was in discordance with accepted genetic relationships. These dissimilarities between TD-MSAP and other marker systems can be informative for understanding the genetic relationships between the species.

Juniperus drupacea Labill is a unique representative tree which, nowadays, has limited geographical range. In Greece, it exists only in the southeastern part of the Peloponnese, and it is labeled as endangered according to the IUCN in Europe. In the light of climatic changes, a conservation plan which will secure its adaptation and resilience is important. Knowledge of the genetic and the epigenetic diversity of J. drupacea in Greece can establish a pledge for sustainability. In this study, genetic diversity with amplified fragment length polymorphism (AFLP) markers and epigenetic diversity assessed with methylation-sensitive amplification polymorphism (MSAP) were used for eleven subpopulations of the species. Simultaneously, first assessment between midday water potential (Ψmd) and epigenetic diversity was calculated in order to determine drought response of the species. Results showed that genetic diversity was higher than epigenetic diversity and no subpopulation differentiation was observed. No significant correlations were found between geographic, epigenetic, and genetic diversity, indicating that the genetic diversity is uncoupled from epigenetic diversity. A significant negative correlation between epigenetic Shannon index and Ψmd was found. The holistic research of genetic and epigenetic diversity paves the way for an effective conservation plan for the species.

The mechanisms underlying heritable phenotypic divergence associated with adaptation in response to environmental stresses may involve both genetic and epigenetic variations. Several prior studies have revealed even higher levels of epigenetic variation than genetic variation. However, few population‐level studies have explored the effects of epigenetic variation on species with high levels of genetic diversity distributed across different habitats. Using AFLP and methylation‐sensitive AFLP markers, we tested the hypothesis that epigenetic variation may contribute to differences in plants occupying different habitats when genetic variation alone cannot fully explain adaptation. As a cosmopolitan invasive species, Phragmites australis (common reed) together with high genetic diversity and remarkable adaptability has been suggested as a model for responses to global change and indicators of environmental fluctuations. We found high levels of genetic and epigenetic diversity and significant genetic/epigenetic structure within each of 12 studied populations sampled from four natural habitats of P. australis. Possible adaptive epigenetic variation was suggested by significant correlations between DNA methylation‐based epigenetic differentiation and adaptive genetic divergence in populations across the habitats. Meanwhile, various AMOVAs indicated that some epigenetic differences may respond to various local habitats. A partial Mantel test was used to tease out the correlations between genetic/epigenetic variation and habitat after controlling for the correlation between genetic and epigenetic variations. We found that epigenetic diversity was affected mostly by soil nutrient availability, suggesting that at least some epigenetic differentiation occurred independently of genetic variation. We also found stronger correlations between epigenetic variation and phenotypic traits than between genetic variation and such traits. Overall, our findings indicate that genetically based differentiation correlates with heterogeneous habitats, while epigenetic variation plays an important role in ecological differentiation in natural populations of P. australis. In addition, our results suggest that when assessing global change responses of plant species, intraspecific variation needs to be considered.

AimEstuarine vegetation routinely experiences natural tidal fluctuations and is highly vulnerable to extreme events such as heavy rainfall, leading to changes in plant population structure and adaptability. Genetic and epigenetic modifications are widely considered to be mechanisms of phenotypic variation, triggered in plants responding to extreme changing environments. However, understanding on correlations among genetic, epigenetic, and phenotypic variation of wild plant populations is still limited.LocationChina.MethodsIn this study, populations of the typical wetland clonal species Phragmites australis were selected from four estuaries along various latitudes in China. Genetic and epigenetic diversity and phenotypic variation of these populations were analysed.ResultsPhenotypic variation of P. australis populations was the highest at Yellow River Estuary and the lowest at Min River Estuary. Across all estuaries, Genetic and epigenetic diversity was strongly linear‐correlated. Genetic diversity had significant correlations with variation in reproductive traits, whereas epigenetic diversity had significant correlations with variation in growth traits. Climatic factors of mean annual temperature and precipitation, as well as soil nitrogen and phosphorus, were negatively correlated with variation in genetic diversity, epigenetic diversity, and variation in reproductive traits of P. australis populations along latitudes. Variation in growth traits was negatively correlated with soil salinity, reflecting the limiting effect of salinity on plant growth.Main ConclusionOur findings found that genetic and epigenetic variations may play different roles in phenotypic variation of P. australis populations along latitudes, the variation becomes greater when the climatic and edaphic conditions deteriorate. The findings shed new light on the adaptation and evolution of wetland plant populations along a large latitudinal scale, and may contribute to the revegetation of estuary wetlands.

Ecological adaptation plays an important role in the process of plant expansion, and genetics and epigenetics are important in the process of plant adaptation. In this study, genetic and epigenetic analyses and soil properties were performed on D. angustifolia of 17 populations, which were selected in the tundra zone on the western slope of the Changbai Mountains. Our results showed that the levels of genetic and epigenetic diversity of D. angustifolia were relatively low, and the main variation occurred among different populations (amplified fragment length polymorphism (AFLP): 95%, methylation sensitive amplification polymorphism (MSAP): 87%). In addition, DNA methylation levels varied from 23.36% to 35.70%. Principal component analysis (PCA) results showed that soil properties of different populations were heterogeneous. Correlation analyses showed that soil moisture, pH and total nitrogen were significantly correlated with genetic diversity of D. angustifolia, and soil temperature and pH were closely related to epigenetic diversity. Simple Mantel tests and partial Mantel tests showed that genetic variation significantly correlated with habitat or geographical distance. However, the correlation between epigenetic variation and habitat or geographical distance was not significant. Our results showed that, in the case of low genetic variation and genetic diversity, epigenetic variation and DNA methylation may provide a basis for the adaptation of D. angustifolia.

The stone pine (Pinus pinea L.) is an evergreen coniferous species valued for its edible seeds, which provide significant economic benefits to local populations. Remarkable phenotypic plasticity but low genetic variation characterizes the species. In Greece, natural populations of P. pinea are part of the Natura 2000 network and are protected under Annex I Priority Habitat type 2270. These populations, located across six Natura 2000 sites (including two islands), face increasing threats from tourism and climate change, leading to ecosystem degradation. Genetic and epigenetic studies are critical for the conservation of forest species because they provide insights into the genetic diversity, adaptive potential, and resilience of species, helping to inform effective management strategies and protect biodiversity in changing environments. This study aims to assess the genetic and epigenetic diversity of P. pinea in four Natura 2000 sites using molecular markers and to propose conservation strategies to ensure the species' long-term sustainability. Additionally, a preliminary investigation of water potential under maximum daily water demand was conducted to evaluate the species' adaptive response. Genetic analysis was performed using Amplified Fragment Length Polymorphism (AFLP) markers, while epigenetic analysis was conducted using Methylation-Susceptible Amplified Polymorphism (MSAP) markers. Sampling was carried out in four Natura 2000 areas, where genetic and epigenetic diversity patterns were examined. Furthermore, a preliminary study on water potential under peak daily water demand conditions was conducted to assess the species' physiological adaptation to environmental stress. The results of this study provide valuable insights into conservation strategies by highlighting the potential role of epigenetic variation in the adaptability of P. pinea, despite its low genetic variability. Understanding the species' epigenetic flexibility can inform conservation efforts aimed at enhancing its resilience to environmental stressors, such as climate change. Additionally, the preliminary water potential analysis contributes to identifying physiological traits that may help predict the species' survival under varying environmental conditions, guiding the development of more targeted conservation practices and management plans. Further research could refine these findings and strengthen their application in conservation efforts. The conclusions emphasize the critical importance of this research in informing conservation efforts for P. pinea in Greece, particularly considering climate change and human pressures. The results highlight the need for both in-situ and ex-situ conservation strategies to ensure the long-term sustainability of the species. The key recommendations include the protection of natural habitats, the implementation of controlled seed collection practices, and further research into the epigenetic mechanisms that may enhance the species' resilience to environmental stress. Future studies should focus on deepening our understanding of these epigenetic factors and their role in the adaptability of P. pinea, which will be essential for developing more effective conservation measures.

Uniola paniculata, commonly known as sea oats, is a C4 perennial grass capable of stabilizing sand dunes. It is most abundant along the Gulf of Mexico and southeastern Atlantic coastal regions of the United States. The species exhibits low seed set and low rates of germination and seedling emergence, and so extensive clonal reproduction is achieved through production of rhizomes, which may contribute to a decline in genetic diversity. To date, there has been no systematic assessment of genetic variability and population structure in naturally occurring stands in the USA. This study was conducted to assess the genetic relationship and diversity among nineteen U. paniculata accessions representing eight states: Texas, Louisiana, Mississippi, Alabama, Florida, South Carolina, North Carolina, and Virginia, using amplified fragment length polymorphism (AFLP). Twelve AFLP EcoRI + MseI primer combinations generated a wide range of polymorphisms (42-81%) with a mean of 59%. Overall, the sea oats plants exhibited a low range of genetic similarity. Florida accessions, FL-33 and FL-39, were most genetically diverse and the accessions from both Carolinas and Virginia (NC-1, NC-11, SC-15, and VA-53) harbored less genetic variability. Cluster analysis using the UPGMA approach separated U. paniculata plants into four major clusters which were also confirmed by principal coordinate analysis (PCO). Further examination of the different components of genetic variation by analysis of molecular variance (AMOVA) indicated the largest proportion of variability at the state level (47.8%) followed by the variation due to the differences among the genotypes within an accession (34.4%), and the differences among the accessions within a state (17.8%). The relationship between genetic diversity and geographic source of sea oats populations of the United States as revealed through this comprehensive study will be helpful to resource managers and commercial nurseries in identifying suitable plant materials for restoration of new areas without compromising the adaptation and genetic diversity.

The adaptive capacity of a species and its population is determined by both genetic and epigenetic variation, which defines the potential for adaptive evolution and plastic response to environmental changes. In this study, we used Methylation Sensitive Amplified Polymorphism (MSAP) and Amplified Fragment Length Polymorphism (AFLP), similar genome-wide profiling techniques, to analyze the epigenetic and genetic variability in European beech provenances from Germany (DE), Spain (ES) and Sweden (SE), representing the latitudinal distribution of the species. In addition, we evaluated the effect of moderate water stress on cytosine methylation dynamics by comparing two latitudinal contrasting provenances. Our analysis revealed that trees from ES showed lower values of epigenetic and genetic diversity than those from DE and SE. Analyses of molecular variance for MSAPs and AFLPs showed that 16% and 15% of the among population variations were associated with epigenetic and genetic variation, respectively. The study of the effect of water stress on cytosine methylation dynamics in seedlings from ES and SE revealed no significant levels of epigenetic differentiation between well-watered and stressed plants. Only 2% of the epigenetic variation was explained by the watering regime in ES without changes in SE. The results support that DNA methylation may play a role in the local adaptation of Fagus sylvatica to environmental variation.

Environmentally induced phenotypic plasticity is thought to play an important role in the adaption of plant populations to heterogeneous habitat conditions, and yet the importance of epigenetic variation as a mechanism of adaptive plasticity in natural plant populations still merits further research. In this study, we investigated populations of Vitex negundo var. heterophylla (Chinese chastetree) from adjacent habitat types at seven sampling sites. Using several functional traits, we detected a significant differentiation between habitat types. With amplified fragment length polymorphisms (AFLP) and methylation‐sensitive AFLP (MSAP), we found relatively high levels of genetic and epigenetic diversity but very low genetic and epigenetic differences between habitats within sites. Bayesian clustering showed a remarkable habitat‐related differentiation and more genetic loci associated with the habitat type than epigenetic, suggesting that the adaptation to the habitat is genetically based. However, we did not find any significant correlation between genetic or epigenetic variation and habitat using simple and partial Mantel tests. Moreover, we found no correlation between genetic and ecologically relevant phenotypic variation and a significant correlation between epigenetic and phenotypic variation. Although we did not find any direct relationship between epigenetic variation and habitat environment, our findings suggest that epigenetic variation may complement genetic variation as a source of functional phenotypic diversity associated with adaptation to the heterogeneous habitat in natural plant populations.

Liu, Y., Fu, Y.-B. and Coulman, B. E. 2013. Evaluating genetic variation and relationships amongPuccinellia nuttallianapopulations using amplified fragment length polymorphism markers. Can. J. Plant Sci. 93: 1097-1104. Nuttall's salt-meadow, or alkali grass [Puccinellia nuttalliana (Shultes) Hitchc.], is a native grass species in North America, well known for its salt tolerance. Little information is available about the genetic diversity of natural populations of this species. Amplified fragment length polymorphism (AFLP) markers were used to examine the inter-population relationships and to compare variances within and among 23 populations collected from the Canadian Great Plains. Five AFLP primer pairs were employed to screen 15 genotypes (five sets of three half-sib plants) from each population, and 185 polymorphic AFLP bands were scored for each sample. The frequencies of these scored bands ranged from 0.02 to 0.99 with a mean of 0.60. The analysis of molecular variance revealed more than 96% of the total AFLP variation resided within populations. Populations were not highly differentiated with only 4% of the total AFLP variation residing among populations. A Mantel test revealed a significant but low correlation between genetic and geographic distances (r=0.29, P=0.024). Implications for P. nuttalliana conservation, germplasm sampling, and cultivar development are discussed.

BackgroundThe main bottleneck to elevate jatropha (Jatropha curcas L.) from a wild species to a profitable biodiesel crop is the low genetic and phenotypic variation found in different regions of the world, hampering efficient plant breeding for productivity traits. In this study, 182 accessions from Asia (91), Africa (35), South America (9) and Central America (47) were evaluated at genetic and phenotypic level to find genetic variation and important traits for oilseed production.ResultsGenetic variation was assessed with SSR (Simple Sequence Repeat), TRAP (Target Region Amplification Polymorphism) and AFLP (Amplified fragment length polymorphism) techniques. Phenotypic variation included seed morphological characteristics, seed oil content and fatty acid composition and early growth traits. Jaccard’s similarity and cluster analysis by UPGM (Unweighted Paired Group Method) with arithmetic mean and PCA (Principle Component Analysis) indicated higher variability in Central American accessions compared to Asian, African and South American accessions. Polymorphism Information Content (PIC) values ranged from 0 to 0.65. In the set of Central American accessions. PIC values were higher than in other regions. Accessions from the Central American population contain alleles that were not found in the accessions from other populations. Analysis of Molecular Variance (AMOVA; P < 0.0001) indicated high genetic variation within regions (81.7%) and low variation across regions (18.3%). A high level of genetic variation was found on early growth traits and on components of the relative growth rate (specific leaf area, leaf weight, leaf weight ratio and net assimilation rate) as indicated by significant differences between accessions and by the high heritability values (50–88%). The fatty acid composition of jatropha oil significantly differed (P < 0.05) between regions.ConclusionsThe pool of Central American accessions showed very large genetic variation as assessed by DNA-marker variation compared to accessions from other regions. Central American accessions also showed the highest phenotypic variation and should be considered as the most important source for plant breeding. Some variation in early growth traits was found within a group of accessions from Asia and Africa, while these accessions did not differ in a single DNA-marker, possibly indicating epigenetic variation.

PDF HTML阅读 XML下载 导出引用 引用提醒 内蒙古荒漠草原植物遗传多样性对模拟增温处理的响应 DOI: 10.5846/stxb201504220826 作者: 作者单位: 中国农业科学院草原研究所;内蒙古农业大学生命科学学院,中国农业科学院草原研究所：内蒙古农业大学生命科学学院,中国农业科学院草原研究所,中国农业科学院草原研究所,内蒙古农业大学生态与环境学院,中国农业科学院草原研究所;内蒙古农业大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 内蒙古自治区自然科学基金资助项目（2015MS0305）；中国科学院西部之光“人才培养”项目；中国农业科学院草原研究所科技创新工程资助项目 The response of genetic diversity in desert steppe plants to simulated warming in Inner Mongolia, China Author: Affiliation: Institute of Grassland Research, Chinese Academy of Agricultural Sciences;College of Life Sciences, Inner Mongolia Agricultural University,,,,,Institute of Grassland Research, Chinese Academy of Agricultural Sciences;College of Life Science, Inner Mongolia Agricultural University, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为探究全球变暖对温带荒漠草原地上种群的遗传影响，对已经接受模拟增温处理6年的短花针茅草原4种不同生活型植物，即半灌木、多年生禾草、多年生杂类草和一年生植物，应用AFLP分子标记方法研究了其遗传多样性和遗传结构。结果显示，对照处理与增温处理下的木地肤、短花针茅、细叶葱、猪毛菜4种植物的多态位点百分率（PPB）分别为11.32%，11.32%；40.83%，39.91%；14.29%，13.10%；19.85%，19.12%。Nei's基因多样性指数（He）分别为0.0274，0.0259；0.0812，0.0899；0.0131，0.0084；0.0506，0.0456。Shannon's信息指数值（I）分别为0.0447，0.0430；0.1354，0.1466；0.0267，0.0182；0.0811，0.0733。分子方差分析（AMOVA）显示4种植物的变异主要来源于实验处理内部，木地肤为85.03%，短花针茅为66.35%，细叶葱为70.00%，猪毛菜为66.52%；增温处理间的变异分别占-2.81%，-5.47%，-3.60%，2.53%（P>0.05）。4种植物增温处理与变异程度之间在统计学上并无相关性。研究表明虽然短时间的模拟增温并不足以使4种生活型植物种群遗传多样性和遗传结构发生显著变化，但相对于3种多年生植物，一年生植物猪毛菜更容易受到增温影响。多年生和一年生植物对增温具有不同的遗传响应。 Abstract:Climate is the most important factor that determines vegetation types and the distribution of species, and, accordingly, these features are two of the most prominent indicators of climate change. Currently, scientists generally agree that climate change will inevitably lead to changes in plant community structure and function, and if this change continues, the effects will be profound and enduring. Existing research shows that simulated warming causes an increase in biomass in Deschampsia caespitosa, Carex alrofusca, and Leymus chinensis; as climates change, these constructive species and their main companion species within a Kobresia humilis meadow have experienced an advancement in their spring phenology and a delay in their autumn phenophase. In addition, the photosynthetic rate of Deschampsia caespitosa in a Northwest Sichuan alpine meadow has increased. Although the change in stomatal conductance was irregular, a significant decrease has also been observed in the sodium, potassium, and phosphorus content of leaves. However, relatively little research has been conducted on the effects of simulated warming on the genetic structure and diversity of plant populations. Against the background of global climate change, the temperatures of the Inner Mongolian desert steppe have become unevenly elevated, with average annual temperatures increasing from 8.1℃ in the 1950s to 9.0℃ in the 1990s. The present study explores the effects of global warming on the genetics of wild forage plant populations with different life forms in desert steppe habitat, in an effort to elucidate their potential to adapt to environmental change. The study site was located in the desert steppe in Siziwangqi territory of Inner Mongolia. Suspension infrared radiators were used to create a controlled warming experiment under otherwise natural field conditions. Warming began on May 3, 2006. The average soil temperature at depths of 0, 7.5, 15, 30, and 50 cm increased by 1.32, 0.92, 0.88, 0.80, and 0.74℃, respectively, after warming for 1 year compared with the average in plots not exposed to warming. For this study, changes in genetic diversity and structure were analyzed in four plant populations: (1) small half shrubs, represented by Kochia prostrata; (2) perennial grasses, represented by Stipa breviflora; (3) perennial forbs, represented by Allium tenuissimum; and (4) annuals and biennials, represented by Salsola collina). The study was conducted under simulated warming pressure and genetic analysis was performed using amplified fragment length polymorphism. The percentages of polymorphic loci in K. prostrata, S. breviflora, A. tenuissimum, and S. collina under non-warming were 11.32%, 40.83%, 14.29%, and 19.85%, whereas those under simulated warming were 11.32%, 39.91%, 13.10%, and 19.12%, respectively. The genetic diversity of the four populations measured under control and simulated warming, measured by the Shannon's information index, were as follows: K. prostrata (0.0274, 0.0259), S. breviflora (0.0812, 0.0899), Allium tenuissimum (0.0131, 0.0084), and S. collina (0.0506, 0.0456). These findings exhibited the same distributional pattern as that of Nei's genetic diversity index for K. prostrata (0.0447, 0.0430), S. breviflora (0.1354, 0.1466), Allium tenuissimum (0.0267, 0.0182), and S. collina (0.0811, 0.0733). Cluster analysis of these four species showed that known of the species reacted significantly to the warming process, and that inter-individual clusters were not significantly different. The results of an analysis of molecular variance (AMOVA) indicated that the main source of variation among the four life form populations was within-population variation: K. prostrata (85.03%), S. breviflora (66.35%), A. tenuissimum (70.00%), and S. collina (66.52%). The among-groups variation was not significant and accounted for the following percentages of variation: K. prostrata (-2.81%), S. breviflora (-5.47%), Allium tenuissimum (-3.60%), and S. collina (2.53%). No statistically significant correlation was found between simulated warming and genetic differentiation. This study shows that a short period of simulated warming was not sufficient to create a significant change in genetic diversity and structure for the four life form populations studied here; however, compared with the three types of perennials studied, the annual plant S. collina, is more susceptible to the effects of warming. Perennials and annuals have different genetic responses to warming. This study provides experimental evidence that can reveal the potential adaptation of plants to environmental change for different life forms of wild forage plants of the desert steppe, and will help researchers to predict forage yield and changes in forage quality. 参考文献 相似文献 引证文献

A study was conducted to investigate the genetic diversity of C. radicicola from different regions of Oman and its relationship to populations of C. radicicola from other parts in the Arabian peninsula and the USA. A total of 32 C. radicicola isolates from Oman (23), the United Arab Emirates (UAE) (2), Kuwait (1) and the USA (6) were analyzed using sequences of the internal transcribed spacer region of the ribosomal DNA (ITS rDNA) and amplified fragment length polymorphism (AFLP). AFLP analysis of the 32 isolates produced 32 different genotypes and 999 polymorphic alleles (100% polymorphism). The Omani population of C. radicicola was found to be more genetically diverse (H = 0.274) than the USA population (H = 0.186), which may suggest a longer history of C. radicicola in Oman. UPGMA analysis based on Nei's genetic distance as well as phylogenetic analysis based on ITS rDNA sequences separated the USA isolates from those from Oman, UAE and Kuwait with a very high bootstrap support. This was supported by low to moderate levels of genetic differentiation between populations of C. radicicola within the Arabian peninsula (FST = - 0.0297-0.1341) as compared with high levels of genetic differentiation (FST = 0.2939-0.3913) of the population from the USA. These findings may imply that populations of C. radicicola from the USA and the Arabian peninsula have been evolving independently for a considerably long period of time as opposite to constant gene flow between regions in the Arabian peninsula. Analysis of molecular variance (AMOVA) showed that genetic variation is more associated with geographical regions (FST = 0.1807, P < 0.0001) than hosts (FST = 0.0307, P = 0.1681), which may imply the lack of host "cultivar" specialization in C. radicicola.