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1.
Glycyrrhiza uralensis Fisch. ex DC. (Chinese licorice) is an important medicinal plant in Mongolia. Despite its traditional role in local healing systems, little is known about the existing intra-specific diversity of this species. The aim of the present study therefore was to analyze morphological and genetic diversities of G. uralensis in the Bulgan River Basin in Western Mongolia and to test different treatments aimed at breaking seed dormancy in order to facilitate effective cultivation of this species. Morphological measurements were taken and leaf and seed samples were collected in eight populations of the Bulgan River Basin. Subsequently, DNA was extracted from leaves and analyzed employing amplified fragment length polymorphisms. A total of 11 treatments were used to test and enhance seed germination. Morphological characteristics differed among populations. Treatments used in the study affected total emergence and mean days to germination of the seeds differently, but populations did not differ in their response whereas differentiation within populations was high. Mechanical and acid scarifications were more effective compared to other treatments. The level of genetic diversity in the studied populations was lower than the average value of the short-lived perennial herbs, but close to that of the self-breeding species. Most of the genetic variation was within populations. Chinese licorice is suitable for cultivation in the Bulgan River Basin and effective scarification can increase germination of seeds across the populations collected in our study area.  相似文献   

2.
Tetraena mongolica Maxim, is a critically endangered and endemic species of westem Inner Mongolia in China. Genetic variability within and among eight extant populations of this species was assessed using ISSR PCR (13 primers). We expected a low genetic diversity level, but our results revealed an intermediate level of intraspecific genetic diversity, probably resulting from this species being in a refuge during the last glaciation (at population level: P=48.1%, Ae=1.305, HE=0.177 and Hpop=0.264; at species level: P=63.3%, A=1.368, HT=0.213 and Hsp=0.324). A low level of genetic differentiation among populations was detected based on Nei's genetic diversity analysis (16.91%), Shannon's diversity index (18.83%) and AMOVA (15.2%). Populations shared high levels of genetic identity (I=0.9516±0.013). The extensive gene flow was a plausible reason for the low genetic differentiation.  相似文献   

3.
Genetic variation of wild populations and cultivars of Luohanguo (Siraitia grosvenorii), a plant species endemic to southern China, was assessed using random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) markers. Based on the results for 130 individuals from seven populations, a high level of genetic diversity of Luohanguo was observed at the species level. The percentage of polymorphic loci (P) was 89.4%, Nei’s gene diversity (H e) was 0.239, and Shannon’s information index (H o) was 0.373 based on the combined AFLP and RAPD data. There was a high degree of genetic differentiation, with 45.1% of the genetic variation attributed to differences between the populations. The genetic diversity of the Luohanguo cultivars is much lower than that of wild populations (P = 41.8%, H e = 0.141, H o = 0.211), and a distinct genetic differentiation is observed between the cultivars and wild accessions. The pool of genetic variation in the wild populations provides an excellent gene resource for Luohanguo breeding.  相似文献   

4.
Pilgerodendron uviferum (Cipres de las Guiatecas, Cupressaceae) is a long-lived conifer, endemic to southern Chile and Argentina, reaching a southern limit in Tierra del Fuego. Remnant populations are generally fragmented and highly disturbed because of exploitation for timber, grazing and fire. The extent of genetic variation within and between 16 populations of this species, distributed throughout its range, was assessed using random amplified polymorphic DNA (RAPD) markers. Eight 10-mer primers produced a total of 84 scorable markers, 30 of which (35.7%) were polymorphic. AMOVA indicated that 18.6% of the variation recorded was attributable to differences between populations, a relatively high value compared with other conifers from the region. Pair-wise Phist comparisons between populations were all significant at P<0.05, with one exception, highlighting a high degree of population differentiation. Values of Shannon's diversity index (S) differed significantly among populations (P=0.002, ANOVA), values ranging from 0.337 to 0.716, suggesting that some populations are currently characterised by very low genetic variability. Current patterns of genetic variation were related to biogeographic history and human impact. The high degree of population differentiation recorded here highlights the need for additional conservation measures for this species, both in terms of incorporating further populations into the protected areas, and the restoration of severely degraded populations, to ensure their continued viability.  相似文献   

5.
Anchote (Coccinia abyssinica) is plant endemic in Ethiopia with a high calcium content grown for its edible tuberous roots. In spite of its importance as food security crop, there is no information available on molecular genetic diversity of this crop. Therefore, the aim of this study was to assess genetic diversity within and among 12 populations of anchote using ISSR markers. Using nine ISSR primers, a total of 87 scorable bands was generated of which 74 were polymorphic. Within population diversity based on polymorphic bands ranged from 13.8 to 43.53 % with a mean of 33.05 %, Nei’s genetic diversity of 0.04–0.156 with a mean of 0.12, Shannon information index of 0.07–0.23 with a mean of 0.175 and analysis of molecular variation (AMOVA) of 51.4 % were detected. With all diversity parameters, the highest diversity was obtained from Gimbi, Bedele and Ale populations, whilst the lowest was from Manna. AMOVA showed a 48.56 % between populations variability and significantly lower than that of within population variation. Population differentiation with FST was 48.56 %. From Jaccard’s pairwise similarity coefficient, Decha and Nedjo were most related populations exhibiting 0.76 similarity and Manna and Nedjo were the most distantly related populations with similarity of 0.52. The only pentanucliotide primer used in the study, Primer 880 (GGAGA)3, showed a unique band in some individuals that appeared to be associated with morphological quantitative traits (lowest seed number, high protein content, largest fruit size and smallest vine length). Illubabor and Gimbi populations exhibited highest genetic diversity so that the populations should be considered as the primary sites in designing conservation areas for this crop.  相似文献   

6.
The relative importance of ecological and genetic factors in regulating the demographic processes of small populations is unknown for most rare plants. Dithyrea maritima (beach spectacle pod; Brassicaceae) is a rare, rhizomatously spreading, and self-incompatible herbaceous perennial endemic to coastal sand dunes of southern California. Low seed production in this species may be caused by insufficient pollinator visits, which may be exacerbated by competition for pollinator visits from non-native plants that have invaded the coastal dunes. I tested this ‘ecological’ hypothesis by removing flowers of Cakile maritima and Carpobrotus spp. from three experimental plots on San Nicolas Island. A second possible limitation on seed set is low diversity of genets within subpopulations, which could lead to scarcity of compatible mates. I tested this ‘genetic’ hypothesis by assigning ramets to clones using isozymes, and by relating clonal diversity within populations to seed set. Removal of non-native plants had no detectable effect on pollination service to D. maritima or on seed set, and seed set was unrelated to natural variation in pollination service among populations within a single year. In contrast, clonal diversity within a 10 m2 patch was a strong predictor of seed set. Hence a genetic factor explains spatial variation in seed set on San Nicolas Island. On larger spatial and temporal scales, however, pollination service also affects patterns of seed set: a shift in pollination from flies in 1998 to bees in 1999 probably caused a corresponding increase in seed set across San Nicolas Island, while extremely low seed set at another site (San Miguel Island) is probably caused by a virtual absence of pollinators there.  相似文献   

7.
There is much concern over the high mortality of many populations of Acacia raddiana, a keystone tree species in the Negev desert of Israel. We used random amplified polymorphic DNA (RAPD) to assess patterns of genetic variation within and among 12 populations of A. raddiana from the Arava (Syrian-African Rift) valley and western Negev. A high level of genetic polymorphism was recorded within populations. An analysis of molecular variance (AMOVA) showed that about 59.4% of total genetic variance occurred among populations, which is considerably greater population differentiation than that recorded for other outbreeding species. Cluster and principal coordinates analyses and AMOVA indicate that the western Negev and Arava valley populations are highly differentiated. We suggest that there may have been two invasions of A. raddiana into Israel: one across the northern Sinai/Gaza Strip area into the western Negev, with some plants reaching the Dead Sea and a second invasion across the southern part of the Sinai peninsula, or even from Saudi Arabia, up to the Arava valley. From the conservation point of view, each population should be conserved separately because they are genetically highly differentiated and loss of any one population would lead to a dramatic loss of genetic variation. The mixing of genetically distinct populations may give rise to outbreeding depression (particularly because of GXE interactions). An obvious first step to the maintenance of this species' genetic diversity is the separate management of the western Negev and Arava valley populations because of their different evolutionary histories.  相似文献   

8.
Using random amplified polymorphic DNA (RAPD) markers, we examined genetic variability of the moss Thuidium cymbifolium (Thuidiaceae) sampled from three types of spruce (Picea asperata) stands: an intact stand, naturally regenerated stands after clearcut harvests, and planted stands after clearcut harvests in the Miyaluo area, western Sichuan of China. Stands of the latter two types were of various age since the last clearcut. Results showed that the population of T. cymbifolium from the intact stand displayed the highest level of genetic diversity, and populations from the planted stands exhibited significantly higher levels than the naturally regenerated stands. In planted stands, genetic variation within populations increased over time. These findings indicated that habitat destruction by forest harvesting led to the reduction in genetic variation within populations, but that given time, artificial reforestation after clearcut was effective in promoting the recovery of genetic diversity in the recolonized moss species. Therefore, lengthening the normal felling rotation of plantations should be favored to restore and conserve genetic diversity in recolonized species. In addition, thinning young plantations via selective logging may provide heterogenous microhabitats similar to those in the old stands, and thereby facilitate the development of bryophyte communities and the increase of genetic variation of the recolonized mosses.  相似文献   

9.
Different conservation measures including domestication approaches are needed to preserve rare and extensively used plant species and to satisfy future market demands. Snow lotus (a common name used for a number of high altitude species in central Asia) species in Mongolia are important medicinal plants, mostly endangered at the regional level due to the extensive use for medicinal purposes and naturally limited distribution ranges. In order to develop effective conservation and cultivation approaches we studied the morphological and genetic diversity as well as the seed germination behavior of three populations of Saussurea involucrata in the Altay Mountains of Western Mongolia. Plant height and leaf length were measured on 41–53 randomly selected individuals in each population. Enhancement of seed germination was studied using either mechanical or chemical scarification with potassium nitrate and gibberellic acid. Genetic diversity within and among three populations of the species was analyzed using Amplified Fragment Length Polymorphisms. Plants in three populations differed in height and leaf length (P < 0.001). Plant size tended to be negatively correlated with habitat altitude. Seed germination rate was low and increased with seed soaking in gibberellic acid. However, the response of seeds to different treatments was rather population-specific. Most treatments did not significantly affect mean days to germination and the ratio of shoot to root dry weight of 2-weeks old seedlings. The level of genetic diversity in the studied populations was lower than the average value for other long-lived perennial herbs. Analysis of molecular variance revealed a high differentiation within populations (92 % of total variation) indicating sufficient gene flow among populations.  相似文献   

10.
Levels of genetic variation and intrapopulation genetic structures of Leontice microrhyncha S. Moore (Berberidaceae) were assessed for six populations in South Korea, representing the southern most range of a species found in Northeast China and the Korean peninsula. Detected genetic diversity (Hes) was very low (0.024) and FIS values showed large heterozygote deficiencies. The small percentage of polymorphic loci and numbers of alleles per locus suggest that L. microrhyncha has a history of severe or long-lasting population bottlenecks that have eroded genetic diversity. This study suggests that the Korean population appears to consist of two historically isolated and independently evolving populations. It seems likely that these groups have been isolated and unstable for a significant period of time. However, the effects of recent habitat fragmentation on the historically disjunct and fragmented population system found in L. microrhyncha were not those predicted from the lack of significant relationships between population-level patterns of genetic variation and population sizes. Most non-unique genotypes were shared by most individuals and the lower level of diversity, high levels of inbreeding and population differentiation as well as high rate of seed production indicated that this species is autogamous and self-compatible and probably largely selfing. Therefore, to preserve extant genetic variation, all populations must be protected across the small geographic range of the species to retain both allelic and genotypic diversity.  相似文献   

11.
Chinese Cherry, generally referring to Prunus pseudocerasus Lindl. species, is one of the most economically important domestic fruit tree in China. To effectively preserve and sustainably utilize this species, a study in genetic diversity and population structure was carried out by the sequence variation of chloroplast DNA trnQ-rps16 intergenic spacers. Polymorphism was calculated among the 200 individuals from 7 local and 10 wild populations across its geographical range in China. The results showed that (1) Total genetic variation in species level was poor (h = 0.478, π = 0.0018). But in the wild populations, it was much higher than that in the local populations (h = 0.565, π = 0.0021 vs. h = 0.152, π = 0.0006). (2) Low levels of genetic differentiation (FSC = 0.19595, P = 0.000), genetic distance (0.00000–0.00297), as well as pairwise Fst value among populations were detected. These results, combined with the insignificant gene genealogy pattern and neutrality tests indicate that Chinese Cherry has relatively low levels of genetic diversity and insignificant population structure. Coancestry might be a combined effect of the reduction in effective population size with the recent demographic bottlenecks and mating systems. The pronounced seed dispersal abilities and relatively high rates of gene exchange are supported by the limited genetic differentiation among populations.  相似文献   

12.
应用RAPD分析川西北高原老芒麦自然居群的遗传多样性   总被引：1，自引：0，他引：1  
利用RAPD标记对来自青藏高原东南部川西北高原的8个老芒麦自然居群的遗传多样性和群体遗传结构进行了分析和评价。从150个RAPD引物中筛选出25个能扩增出高度重复性条带的引物。这25个引物共扩增出370条可分辨的条带,其中291条(占78.65%) 具有多态性,表明供试居群在物种水平上存在较高水平的变异。同时各居群的多态性位点比率(PP)在46.49%到53.78%之间变化,表明群体水平的变异较低。居群的平均基因多样性(HE)为0.176(变幅为0.159~0.190),而物种水平的平均基因多样性达0.264。基于Nei’s基因多样性、Shannon指数和贝叶斯方法的群体分化系数分别为32.0%、33.7%和33.5%。AMOVA 分析表明居群内遗传达到总变异的59.9%,而居群间变异仅有40.1%,但二者均达到极显著水平(P < 0.001)。居群间每世代迁入个体数(Nm)达到0.503个。各居群间存在较高的Nei’s遗传一致度。本研究获得的老芒麦的遗传结构不同于已报导的大多数披碱草属物种。另外,基于聚类分析及AMOVA的结果均表明各居群间存在较为明显的地理分化,8个居群分化为采集地的南部和北部2个分支。总之,研究结果表明来自青藏高原东南部的老芒麦居群具有较高水平的遗传变异。在该地区应尽量选择遗传多样性高的老芒麦居群实施就地保护。  相似文献   

13.
Panicum virgatum L. (switchgrass) is an obligate outcrossing C4 perennial prairie grass currently being pursued for the production of lignocellulosic ethanol. Commercial production of switchgrass for bioenergy has increased substantially in the United States. Understanding the degree of native genetic diversity within and among switchgrass populations will facilitate effective germplasm improvement, conservation, and management programs. In this study, the genetic diversity and differentiation among natural and agronomic switchgrass populations were analyzed at the molecular level by using random amplified polymorphic (RAPD) DNA markers. The mean genetic diversity among populations ranged from 0.051 ± 0.136 to 0.243 ± 0.214 and the mean genetic similarity among all the switchgrass populations was 0.775. The clustering pattern of switchgrass populations grouped the individuals based on their sites of origin, with agronomic cultivars predominantly separated into distinct clusters. The grouping of individuals within and across the populations was corroborated by principal component analysis. These results are consistent with previous reports for switchgrass accessions. RAPD DNA markers were suitable for quickly estimating the genetic diversity of native and agronomic switchgrass populations, and suggest that introgression of agronomic genes into natural switchgrass populations and subsequent changes in genetic structure may be detectable.  相似文献   

14.
The genetic diversity of 58 wild and weedy populations representing taxa within the V. sativa aggregate from the former USSR, 4 cultivars of V. sativa, 2 accessions of V. cordata and 3 accessions of V. macrocarpa from Mediterranean countries were analysed using randomly amplified DNA fragments (RAPDs) and seed protein electrophoresis (SDS-PAGE). Interspecific variation between taxa in the V. sativa aggregate could readily be detected using both techniques. RAPDs and seed protein patterns were found to be an effective means of identifying accessions that cannot be identified clearly by morphological criteria alone. RAPD and seed protein analysis revealed a clear relationship between observed genetic variation of populations and their geographical distribution. Populations from each region had their own gene pools. Geographical variation was detected in V. segetalis. The degree of genetic divergence between local populations was usually related to proximity. In several locations where wild and weedy populations of different V. sativa agg. taxa grow sympatrically, intermediate forms could be detected at the DNA and protein levels. Both RAPD and seed protein analysis support the view that the V. sativa aggregate consists of 8 taxa warranting recognition at the species level. Several species in this aggregate are evolving intra-specific groups which can readily be detected at the molecular level.  相似文献   

15.
Yam (Dioscorea spp.) is widely cultivated in China and many landraces are maintained by local farmers. However, there is little information available about their diversity and species identity. In this study, inter simple sequence repeat (ISSR) and sequence related amplified polymorphism (SRAP) techniques were used to assess genetic diversity within 21 yam landraces from seven cultivated populations. We observed high level of polymorphism among these landraces, specifically, 95.3 % for ISSR and 93.5 % for SRAP. Analysis of molecular variance revealed a significantly greater variation among the four yam species (40.39 %) and their populations (35.78 %) than within the populations (23.83 %). The unweighted pair group method arithmetic averages clusters and principal component analysis for 21 landraces formed four well-separated groups containing landraces of each of the four species, namely, Dioscorea opposita Thunb., Dioscorea alata L., Dioscorea persimilis Prain et Burkill, and Dioscorea fordii Prain et Burkill. The ISSR and SRAP primers were highly discriminatory among the 21 landraces; all 21 landraces could be easily differentiated using these primers. The average mean of gene flow (Nm = 0.1081) estimated from high genetic differentiation (Gst = 0.8222) suggested that gene flow among the populations was relatively restricted. The lack of genetic diversity within individual yam species suggests that it is critical to develop long-term strategies for enhancing genetic diversity within various yam species.  相似文献   

16.
Genetic variation and genetic structure of black spruce (Picea mariana L.) populations growing in wet land (lowlands) and dry lands (uplands) with different levels of metal contaminations were analyzed using ISSR. Polymorphic loci (P%) ranged from 65% to 90% with a mean of 75%. Nei??s gene diversity (h) varied from 0.264 to 0.359 with a mean of 0.310, and Shannon??s index (I) ranged from 0.381 to 0.524 with a mean of 0.449. The level of genetic variation was higher in populations from wet lands than those from dry lands. Variation within populations accounts for most of total genetic variation. The genetic distance among the black spruce (P. mariana) populations ranged from 0.171 to 0.351. The present study indicates that genetic variation and long-term exposure to metals (more than 30 years) are not associated. Cytological analysis of black spruce seeds from metal-contaminated and -uncontaminated areas showed normal mitotic behavior during prophase, metaphase, anaphase, and telophase.  相似文献   

17.
Isozyme studies of genetic diversity and evolution in Hippophae   总被引：4，自引：0，他引：4  
Summary To provide information on the genetic variation, differentiation and evolution in Hippophae seed samples of 25 populations from China, Finland and Russia were electrophoretically analyzed. Of six loci investigated, four were good genetic markers for identifying species and subspecies. The percentages of polymorphic loci per population were 40.3% and 62.5% at 0.95 and 0.99 polymorphic criteria respectively. The mean number of alleles per locus per population was 2.1. Total genetic diversity in the material was 0.4614. Genetic diversity partitioning showed that there was a large amount of diversity residing within geographical populations (0.1354), between subspecies within species (0.1046) and between species (0.2566) but not between geographical populations (0.0114). There were nearly twice as many negative fixation indices as positive ones in Hippophae populations. The phylogenetic tree agreed very well with botanic classifications of the species and subspecies and their geographical distributions, and quantitatively presented the genetic relationships of 25 populations. A detailed view of the evolutionary stages in Hippophae showed clearly a general decline of similarity as evolutionary divergence continued, which further explained the evolution process in Hippophae.  相似文献   

18.
The development of strategies for in situ, ex situ conservation and reforestation of the monkey puzzle tree (Araucaria araucana), a vulnerable tree endemic to southern South America, has led to an interest in the level and distribution of the genetic diversity of the species. Neutral DNA markers (RAPDs) and quantitative genetic techniques were used to characterise genetic heterogeneity within and among populations from throughout the natural range of the species. Both the level and pattern of genetic variation estimated using the different techniques were essentially uncorrelated. An important discrepancy was found with the neutral markers failing to detect an important quantitative genetic divergence across the Andean Range relating to drought tolerance. This study clearly demonstrates the potential problems associated with making recommendations for conserving the genetic resource of threatened species based solely on neutral marker studies. Alternative approaches are discussed, including a stronger focus on ecologically important traits and the potential use of surrogate measures of genetic variability.  相似文献   

19.
Decreasing habitat fragment area and increasing isolation may cause loss of plant population genetic diversity and increased genetic differentiation between populations. We studied the relation between the historical and the present landscape configuration (i.e., patch area and patch connectivity), and the present management of calcareous grassland fragments on the one hand, and the within and between population genetic structure of 18 Anthyllis vulneraria populations on the other hand. Despite the long-time fragmentation history and the mainly selfing breeding system of the species, we detected very low genetic differentiation (Φst = 0.056) among habitat fragments and no significant isolation-by-distance relation. Average within fragment genetic diversity measured as molecular variance and expected heterozygosity, were relatively high (16.46 and 0.28, respectively), and weakly positively correlated with the current fragment area, most likely because larger fragments contained larger populations. We found no effects of the historical landscape configuration on the genetic diversity of the populations. Our data suggest that the consequences of habitat fragmentation for genetic differentiation and genetic diversity of A. vulneraria are relatively minor which is very likely due to the historical high levels of seed exchange among fragments through grazing and roaming livestock. This study provides indirect evidence that nature management by grazing not only positively affects habitat quality but that it might also mitigate the genetic consequences of habitat fragmentation. From the conservation point of view, this study illustrates the importance of grazing and of the regular transport of livestock between fragments to prevent the long-term effects of fragmentation on the genetic diversity of the populations studied.  相似文献   

20.
The endangered fish species Anaecypris hispanica is restricted to eight disjunct populations in the Portuguese Guadiana drainage. The genetic structure of these populations was studied in order to determine levels of genetic variation within and among populations and suggest implications for conservation of the species. Based on five microsatellite loci, the null hypothesis of population homogeneity was tested. Tests for genetic differentiation revealed highly significant differences for pairwise comparisons between all populations, and substantial overall population subdivision (FST=0.112). All sampled populations contained unique alleles. Our findings indicate marked genetic structuring and emphasise limited dispersal ability. The high levels of genetic diversity detected within and among A. hispanica populations suggest, however, that the observed fragmentation and reduction in population size of some populations during the last two decades, has impacted little on levels of genetic variability. Data imply that most A. hispanica populations should be managed as distinct units and that each has a high conservation value containing unique genetic variation. It is argued that geographic patterns of genetic structuring indicate the existence of eight management units.  相似文献   

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