Detection and analysis of genetic variation in Hordeum spontaneum populations from Israel using RAPD markers

Randomly amplified polymorphic DNA (RAPD) markers were used to analyse genetic diversity within and between Hordeum spontaneum populations sampled from Israel. Nei's index of genetic differentiation was used to partition diversity into within and between population components. Fifty-seven per cent of the variation detected was partitioned within 10 H. spontaneum populations. Using principal component and multiple regression analysis, part of the variation detected between populations was seen to be associated with certain ecogeographical factors. Fifty-eight per cent of the distribution of the phenotypic frequencies of three RAPD phenotypes detected using a single primer in 20 H. spontaneum populations could be accounted for by four ecogeographical variables, suggesting adaptive variation at certain RAPD loci.     

AFLP genetic polymorphism in wild barley (Hordeum spontaneum) populations in Israel

The genetic diversity produced by the amplified fragment length polymorphism (AFLP) method was studied in 94 genotypes of wild barley, Hordeum spontaneum (C. Koch) Thell., originating from ten ecologically and geographically different locations in Israel. Eight primer pairs produced 204 discernible loci of which 189 (93%) were polymorphic. Each genotype had a unique banding profile and the genetic similarity coefficient varied between 0.74 and 0.98. The phenogram generated from these similarities by the UPGMA method did not group genotypes strictly according to their geographical origin, which pattern was also seen in the principal coordinate (PCO) plot. Genetic diversity was larger within (69%) than among (31%) populations. Associations between ecogeographical variables and the mean gene diversity were found at one primer pair. The results are discussed and compared with data obtained by the simple sequence repeat (SSR) method.     

Comparison of multivariate methods for the analysis of genetic resources and adaptation in Phytolacca dodecandra using RAPD

The extent of genetic differentiation among 17 Ethiopian populations (249 individuals) of Phytolacca dodecandra (Endod) sampled along altitudinal gradients that varied from 1600 to 3000 m was investigated using random amplified polymorphic DNA (RAPD). The populations were classified into three altitude groups: lowland (1600–2100 m), central-highland (2101–2500 m) and highland (2500–3000 m). Seventy polymorphic loci scored from 12 RAPD primers, singly or in combination with ecogeographical variables (altitude, longitude, latitude, temperature and rainfall), were used for principal component, discriminant, correlation, and stepwise multiple regression analyses. Principal component analysis (PCA) clearly differentiated lowland and the central-highland populations from those of the highlands independent of their geographical regions. Canonical discriminant analysis separated the lowland plants from those of the highlands with the central-highland plants being intermediate. Classificatory discriminant analysis corrected classification of 92.8% of the 249 plants into their respective three altitude groups. Multiple regression analysis identified a strong association between some RAPDs and altitude, temperature and rainfall, while the variation in most RAPDs was explained by combinations of the different ecogeographical variables. It is hypothesised that the different altitude groups may be (1) chemical and/or physiological ecotypes produced as a result of complex interactions of altitude with climatic and/or edaphic factors, or (2) different in ploidy levels. The significant correlations obtained between population means from some RAPDs and altitude and temperature as well as the strong association of some RAPDs with the ecogeographical variables in the multiple regression analysis suggest that part of the RAPD polymorphism could be adaptive, and responsive to environmental selection. Received: 15 December 1999 / Accepted: 12 February 2000     

Ecological-genomic diversity of microsatellites in wild barley,Hordeum spontaneum,populations in Jordan

We analyzed the ecological-genomic diversity of microsatellites of wild barley, Hordeum spontaneum (C. Koch) Thell., at 18 loci in 306 individuals of 16 populations from Jordan across a southward transect of increasing aridity. The 18 microsatellites revealed a total of 249 alleles, with an average of 13.8 alleles per locus (range 3-29), with nonrandom distribution. The proportion of polymorphic loci per population averaged 0.91 (range 0.83-1.00); gene diversity, He, averaged 0.512 (range 0.38-0.651). We compared the number of alleles of the 18 loci to those found in Israel populations by Turpeinen et al. Out of the 280 alleles, 138 (49.3%) were unique (i.e. occurred in only one of the countries). The percentage of unique alleles in Jordan and Israel populations was 43.0% and 17.9%, respectively, suggesting that Jordan is an important center of origin and diversity of wild barley. Estimates of mean gene diversity were highest in the populations collected near the Golan Heights, such as Shuni North, Shuni South and Jarash. Sixty nine percent of the microsatellite variation was partitioned within populations and 31% between populations. Associations between ecogeographical values and gene diversity were established for eight microsatellite loci. The cluster produced by simple sequence repeat (SSR) data is mostly coincidence with the result of the dendrogram of the Spalax ehrenbergi superspecies of subterranean mole rats in Jordan based on allozyme gene loci. The major soil type in the wild barley habitat of each ecological group was different. Stepwise multiple regression analysis indicated that the variance of gene diversity was explained by altitude (R(2) = 0.362**). These observations suggest that microsatellites are at least partly adaptive and subject to natural selection.     

都支杜鹃遗传多样性的ISSR分析

通过ISSR分子标记对都支杜鹃(Rhododendron shanii)5个居群114个个体的遗传多样性进行了分析。8个引物共检测到69个位点,其中多态位点36个,多态位点百分率 （P） 为52.17%;物种水平的Shannon多样性指数（I）为0.2536,Nei指数（H）为0.1659;居群水平的P、I和H分别平均为32.46%、0.1955和0.1344;Nei’s基因分化系数GST=0.1845,基因流Nm=2.2104;遗传结构的AMOVA分析显示,总的遗传变异中88.3%存在于居群内,11.7%存在于居群间;PCA分析和Splite Tree构建的NJ树均显示居群间分化小;遗传距离与地理距离显著相关。较强的基因流、多年生木本及异交与分布区狭窄等可能是导致都支杜鹃遗传多样性较低的主要原因。目前该种的保护应以就地保护为主,尤其要注意对大居群的保护。     

Electrophoretic differentiation in isolated populations of Lolium rigidum Gaud.

Sixteen wild populations of Lolium rigidum Gaud. were collected from island and mainland locations in Mediterranean Europe and western Asia. Five loci, controlling isozymes at four enzyme systems, were assayed on 60 plants per population using starch gel electrophoresis. Gene diversity measures and Nei’s genetic distance were calculated, and the relationships between the populations were analysed using principal component (PCA) and cluster analyses. All populations were found to show a gene diversity index that is consistent with that expected in a cross-fertilising species. The highest gene diversity measures were recorded in some of the island populations. Both PCA and cluster analysis grouped the Balearic Island populations together and separated the Spanish and Sardinian populations from any of the others. The results are discussed with respect to a number of theories of migration between populations, and in relation to the colonization history of each island. It is suggested that the preservation of these island populations in gene banks is important as part of a core collection of the species.     

RAPD polymorphism of wild emmer wheat populations, Triticum dicoccoides, in Israel

 Genetic diversity in random amplified polymorphic DNAs (RAPDs) was studied in 110 genotypes of the tetraploid wild progenitor of wheat, Triticum dicoccoides, from 11 populations sampled in Israel and Turkey. Our results show high level of diversity of RAPD markers in wild wheat populations in Israel. The ten primers used in this study amplified 59 scorable RAPD loci of which 48 (81.4%) were polymorphic and 11 monomorphic. RAPD analysis was found to be highly effective in distinguishing genotypes of T. dicoccoides originating from diverse ecogeographical sites in Israel and Turkey, with 95.5% of the 100 genotypes correctly classified into sites of origin by discriminant analysis based on RAPD genotyping. However, interpopulation genetic distances showed no association with geographic distance between the population sites of origin, negating a simple isolation by distance model. Spatial autocorrelation of RAPD frequencies suggests that migration is not influential. Our present RAPD results are non-random and in agreement with the previously obtained allozyme patterns, although the genetic diversity values obtained with RAPDs are much higher than the allozyme values. Significant correlates of RAPD markers with various climatic and soil factors suggest that, as in the case of allozymes, natural selection causes adaptive RAPD ecogeographical differentiation. The results obtained suggest that RAPD markers are useful for the estimation of genetic diversity in wild material of T. dicoccoides and the identification of suitable parents for the development of mapping populations for the tagging of agronomically important traits derived from T. dicoccoides. Received: 13 July 1998 / Accepted: 13 August 1998     

Assessing the allozyme variation in cultivars and Swedish landraces of rye (Secale cereale L.)

Genetic interpretation and diversity of 9 isozyme loci have been estimated in 7 improved varieties and 19 landraces from Sweden by means of starch gel electrophoresis. The isozyme systems were ACO, DIA, GPI, MDH, PGD and PGM. For the statistic analysis we used the following measures: average number of alleles per locus, percentage of polymorphic loci, average heterozygosity direct count and average heterozygosity Hardy-Weinberg expected unbiased estimate. The measures were made on species and population levels. The distribution of the total genetic diversity among populations was also calculated. To illustrate the genetic relationships among populations, genetic distances were measured and principal component analysis performed. As expected in a cross-pollinated crop we found high genetic diversity and a larger variation within than among the populations. Somewhat unexpectedly, however, we found that the currently used varieties have the same high level of heterozygosity as the landraces but in the dendrogram the two groups are separated. The dendrogram showed three main clusters. The large cluster included 21 populations and the two small clusters were clearly distinguishable from the rest. The landrace spring-type could not be separated from the landraces winter-type, but we did detect a difference between different spring types. A few populations had unique alleles for certain loci.     

Microsatellite polymorphism in natural populations of wild emmer wheat,Triticum dicoccoides,in Israel

Diversity in 20 microsatellite loci of wild emmer wheat, Triticum dicoccoides, was examined in 15 populations (135 genotypes) representing a wide range of ecological conditions of soil, temperature, and water availability, in Israel and Turkey. An extensive amount of diversity at microsatellite loci was observed despite the predominantly selfing nature of this plant species. The 20 Gatersleben wheat microsatellites (GWM), representing 13 chromosomes of genomes A and B of wheat, revealed a total of 364 alleles, with an average of 18 alleles per GWM marker (range: 5–26). The proportion of polymorphic loci per population averaged 0.90 (range: 0.45– 1.00); genic diversity, He, averaged 0.50 (range 0.094– 0.736); and Shannon’s information index averaged 0.84 (range 0.166–1.307). The coefficients of genetic distance between populations were high and averaged D=1.862 (range 0.876–3.320), an indication of sharp genetic divergence over short distances. Interpopulation genetic distances showed no association with geographic distance between the population sites of origin, which ruled out a simple isolation by distance model. Genetic dissimilarity values between genotypes were used to produce a dendrogram of the relationships among wild wheat populations by the unweighted pair-group method with arithmetic averages (UPGMA). The results showed that all the wild emmer wheat populations could be distinguished. Microsatellite analysis was found to be highly effective in distinguishing genotypes of T. dicoccoides, originating from diverse ecogeographical sites in Israel and Turkey, with 88% of the 135 genotypes correctly classified into sites of origin by discriminant analysis. Our present microsatellite results are non-random and in agreement with the previously obtained allozyme and RAPD patterns, although the genetic-diversity values obtained with microsatellites are much higher. Significant correlates of microsatellite markers with various climatic and soil factors suggest that, as in allozymes and RAPDs, natural selection causes adaptive microsatellite ecogeographical differentiation, not only in coding, but most importantly in non-coding genomic regions. Hence, the concept of ”junk DNA” needs to be replaced by at least partly regulatory DNA. The obtained results suggest that microsatellite markers are useful for the estimation of genetic diversity in natural populations of T. dicoccoides and for the tagging of agronomically important traits derived from wild emmer wheat. Received: 27 February 2001 / Accepted: 22 March 2001     

云南金钱槭形态变异与遗传变异的相关性研究

对我国特有珍稀濒危保护植物云南金钱槭的形态变异水平、遗传变异模式以及两者之间的相关性进行了研究。形态学性状分析结果表明 :各居群形态性状变异系数的平均值从大到小排列为 :文山居群 (WSh)、屏边居群 (PB)、黑龙潭居群 (HL T)、蒙自居群 (MZ) ;文山居群与屏边、黑龙潭、蒙自居群间已产生显著或极显著水平的形态差异 ,而后三者间的差异未达显著水平。RAPD分析检测到 10 3个位点 ,其中多态位点 84个 ,云南金钱槭物种水平的多态位点比率为 81.5 5 % ,与其它珍稀濒危植物相比该种的遗传多样性水平不低。 AMOVA和 N ei基因多样性指数分析显示 ,尽管大部分遗传变异仍存在于居群内 (分别为5 7.86 %、5 7.33% ) ,但居群间的遗传变异已达较高水平 (分别为 4 2 .14 %、4 2 .6 7% )。相关分析结果显示 ,云南金钱槭的形态变异与海拔、土壤有机质等生态因子有着显著或极显著水平的相关性 ,但与遗传变异的相关性未达显著水平 ,说明云南金钱槭的形态变异虽然具有一定的遗传基础 ,但可塑性及环境压力对形态变异的产生作用更大一些。基于形态性状和 RAPD数据的聚类分析则进一步说明 ,云南金钱槭的形态变异受到环境因子的强烈影响而与遗传背景的关系不显著     

Correlation between hordatine accumulation, environmental factors and genetic diversity in wild barley (Hordeum spontaneum C. Koch) accessions from the Near East Fertile Crescent

Wild barley shows a large morphological and phenotypic variation, which is associated with ecogeographical factors and correlates with genotypic differences. Diversity of defense related genes and their expression in wild barley has been recognized and has led to attempts to exploit genes from H. spontaneum in breeding programs. The aim of this study was to determine the variation in the accumulation of hordatines, which are Hordeum-specific preformed secondary metabolites with strong and broad antimicrobial activity in vitro, in 50 accessions of H. spontaneum from different habitats in Israel. Differences in the accumulation of hordatines in the seedling stage were significant between different H. spontaneum genotypes from different regional locations and micro-sites. Variation in the hordatine accumulation within genotypes was between 9% and 45%, between genotypes from the same location between 13% and 38%, and between genotypes from different locations up to 121%. Principal component analysis showed that water related factors explain 39%, temperature related factors explain 33% and edaphic factors account for 11% of the observed variation between the populations of H. spontaneum. Genetic analysis of the tested accessions with LP-PCR primers that are specific for genes involved in the biosynthetic pathway of hordatines showed tight correlations between hordatine abundance and genetic diversity of these markers. Multiple regression analyses indicated associations between genetic diversity of genes directly involved in hordatine biosynthesis, ecogeographical factors and the accumulation of hordatines.     

Long-term temporal changes of genetic composition in brown trout (Salmo trutta L.) populations inhabiting an unstable environment

The genetic structure of brown trout (Salmo trutta) populations inhabiting rivers on the island of Bornholm in the Baltic Sea was studied on a spatial and temporal scale. Low water levels in the rivers during the summer period are assumed to have a significant impact on the persistence of local populations, possibly resulting in a metapopulation structure. Extinctions may, however, also be buffered by a remnant strategy, whereby juveniles escape to river outlets during periods of drought. We compared polymorphism at seven microsatellite DNA loci in contemporary and past samples collected from 1944 to 1997. A principal component analysis, a hierarchical gene diversity analysis and assignment tests showed that the genetic composition of populations was not temporally stable, and that temporal genetic differentiation was much stronger than spatial differentiation. Genetic variability was high and stable over time. Effective population sizes (Ne) and migration rate (m) were estimated using a maximum-likelihood-based implementation of the temporal method. Ne estimates were low (ranging from 8.3 to 22.9) and estimates of m were high (between 0.23 and 0.99), in contrast to other Danish trout populations inhabiting larger and more environmentally stable rivers (Ne between 39.2 and 289.9 and m between 0.01 and 0.09). Thus, the observed spatio-temporal patterns of genetic differentiation can be explained by drift in small persisting populations, where levels of genetic variation are maintained by strong gene flow. However, observations of rivers devoid of trout suggested that population turnover also takes place. We suggest that Bornholm trout represent a metapopulation where the genetic structure primarily reflects strong drift and gene flow, combined with occasional extinction-recolonization events.     

新疆阜康绿洲荒漠过渡带叉毛蓬种群遗传多样性及环境适应性研究

本文采用RAPD分子标记分析了新疆阜康绿洲荒漠过渡带叉毛蓬种群的遗传多样性;运用ORIGIN软件,对叉毛蓬种群的遗传多样性和土壤因子进行了回归相关分析。结果表明:叉毛蓬种群具有高的遗传多样性(P=98.7%)。亚种群的Nei基因多样性指数(H)与土壤中的钠离子、氯离子含量显著负相关(P=0.042、P=0.0408);遗传多样性指数与土壤中的电导率、含水量无显著相关关系;多态位点比率(P)与土壤中的全钾含量显著相关(P=0.011),Shannon多样性指数和Nei基因指数与有机质呈极显著负相关(P=0.0030、P=0.0015),与全磷、全氮负相关,但没有达到显著水平。叉毛蓬为旱生植物,利用有限的水分就可以完成生活史,水分没有成为一种限制性因子;土壤中的氯盐在维持叉毛蓬亚种群遗传多样性方面可能起着较为重要的作用,成为与遗传多样性显著相关的限制性因子,对叉毛蓬种群的遗传多样性具有一定的选择压力;同时处于贫瘠土壤上的叉毛蓬机体能够更加完全地利用土壤中的限制性养分,与土壤养分表现出负相关关系。另外,用随机引物检测到的叉毛蓬种群77个位点中有11个位点的基因频率与过渡带土壤因子存在着显著相关,表明这些位点对土壤因子具有特殊的敏感性。新疆阜康地区绿洲荒漠过渡带中叉毛蓬种群的遗传多样性特性可能是亚种群对所处微生境长期适应的结果。     

Microsatellite genetic diversity and differentiation of native and introduced grass carp populations in three continents

Grass carp (Ctenopharyngodon idella), a freshwater species native to China, has been introduced to about 100 countries/regions and poses both biological and environmental challenges to the receiving ecosystems. In this study, we analyzed genetic variation in grass carp from three introduced river systems (Mississippi River Basin in US, Danube River in Hungary, and Tone River in Japan) as well as its native ranges (Yangtze, Pearl, and Amur Rivers) in China using 21 novel microsatellite loci. The allelic richness, observed heterozygosity, and within-population gene diversity were found to be lower in the introduced populations than in the native populations, presumably due to the small founder population size of the former. Significant genetic differentiation was found between all pairwise populations from different rivers. Both principal component analysis and Bayesian clustering analysis revealed obvious genetic distinction between the native and introduced populations. Interestingly, genetic bottlenecks were detected in the Hungarian and Japanese grass carp populations, but not in the North American population, suggesting that the Mississippi River Basin grass carp has experienced rapid population expansion with potential genetic diversification during the half-century since its introduction. Consequently, the combined forces of the founder effect, introduction history, and rapid population expansion help explaining the observed patterns of genetic diversity within and among both native and introduced populations of the grass carp.     

Genetic diversity of Shiraia bambusicola from East China assessed using ISSR markers

To understand the genetic differentiation of the medicinal fungus Shiraia bambusicola, the genetic diversity of 107 individuals from eight populations collected from Jiangsu, Anhui and Zhejiang provinces were studied using inter-simple sequence repeat (ISSR) analysis. The results revealed that the 11 employed primers produced a total of 241 ISSR loci, of which 240 loci (PPB = 99.6%) were polymorphic. Both Nei's gene diversity indexes and Shannon's gene diversity indexes showed that the genetic differentiation of S. bambusicola primarily occurred within the populations. AMOVA revealed that the variation among populations was 40.0%, and the variation within populations was 60.0%. The results of an unweighted pair group method arithmetic average (UPGMA) analysis and a principal coordinate analysis (PCA) revealed that the populations with minimal geographic separations frequently exhibited regional characteristics. These findings revealed that the relationship between sibship and geographical distribution was intensive.     

Genetic differentiation and gene flow between wild and cultivated Prunus avium: An analysis of molecular genetic evidence at a regional scale

The presence of conspecific wild-type and cultivar populations has been a common landscape feature for centuries. As orchards generally continue to expand towards the natural forest, two important issues are raised: the potential reduction of cultivar genetic diversity compared to wild populations and the extent of gene flow between the two population types. These questions were addressed in a study of Prunus avium in northern Greece using nine simple sequence repeat loci to analyse genetic variation in 93 wild-type individuals and 21 cultivars representing the local cultivated germplasm. Results showed a significant reduction of genetic diversity parameters in the cultivated germplasm compared to natural populations. Bayesian, frequency-based and Markov chain – Monte Carlo analyses have revealed that the wild and cultivar groups are genetically divergent and that realized between-group gene flow is almost completely absent. This result was further verified by a principal component analysis showing a clear separation of the two groups in low multivariate space after a principal coordinate analysis. The significant disjunction in flowering time and a considerable geographic distance between the two groups could primarily account for the absence of substantial gene flow. These findings indicate that local wild cherry can provide a source of genetic variation for future breeding in the genetically restricted cultivar group.     

Genogeographic analysis of subdivided population. The Adyge gene pool in the Caucasian gene pool system]

A gene geographic analysis of the indigenous population of the Caucasian historical cultural province was carried out with a set of genetic markers extensively studied in the Adyges (39 alleles of 18 loci): AB0, ACP, C3, FY, GC, GLO, HP, KEL, LEW, MN, MNS, P, PGD, PGM1, RH-C, RH-D, RH-E, and TF. Genetic information on 160 Caucasian populations was used (on average, 65 populations per locus). A synthetic map of the first principal component clearly showed a division into two gene geographic provinces: Northern Caucasus and Transcaucasia. The component significantly differed across the Greater Caucasian Ridge. One of the major regions of extreme values corresponded to the Adyge region. A map of the second component revealed two poles, Northwestern (the Adyges) and Caspian, in gene pool variation of the Caucasian population. The analysis of the maps and the space of principal components showed that the Adyge population is an important component of the Caucasian gene pool. A map of genetic distance from all Caucasian populations to the Adyges showed that the north Caucasian populations (excluding the Ossetes) are the most genetically similar to the Adyges, while Georgians from the Kolkhida Valley and Azerbaijanians from the lowlands near the Caspian Sea and highland steppes are the most genetically remote from the Adyges. The genetic diversity (GST x 10(2)) of the entire Caucasian gene pool was studied. The average diversity of subpopulation within a Caucasian ethnos was GS-E = 0.81, the diversity of ethnoses within a linguistic family was GE-L = 0.83, and the diversity of linguistic families was GL-T = 0.58. The race classification of the Caucasian populations (GS-E = 0.81, GS-R = 0.80, GR-T = 0.76) proved to be more genetically informative than the linguistic one. The major parameters of the Adyges (total diversity HT = 0.364, heterozygosity HS = 0.361, and subpopulation diversity within the ethnos GS-E = 0.69) were similar to those averaged over the entire Caucasian population. A comparison with the same set of genetic markers showed that the interethnic diversity in the Caucasian region was lower than in the other north Eurasian regions (GS-E was 1.24 in the European region, 1.42 in the Ural region, 1.27 in Middle Asia, and 3.85 in Siberia).     

Genetic diversity analysis of Hepatacodium miconioides at different altitude in Tiantal Mountain,Zhejiang Province,China and its relationship with environmental factors

The genetic diversity within and among populations of Hepatacodium miconioides collected at three different altitudes in Tiantai Mountain,Zhejiang Province and its relationships to environmental factors were analyzed by random amplified polymorphic DNA(RAPD)technique.Amplification using 12 random primers of 60 plants and 122 repetitive loci were produced.The percentage of polymorphic loci of three populations ranged from 18.85% to 23.77% with an average of 21.86%,indicating the relatively low genetic diversity of H.miconioides.The average Shannon index of phenotypic diversity(0.1329)and Nei index(0.0925)within populations were relatively low.A distinct genetic differentiation existed among populations Of H miconioides in spite of the relatively small geographical distribufion.The average genetic diversity within populations of H.miconioides accounted for 33.58% of the total genetic diversity while the genetic diversity among populations accounted for 66.42% as estimated by the Shannon index of phenotypic diversity,The genetic differentiation among populations of H.miconioides was 0.6546,as estimated by Nei index.The gene flow estimated from Gsr was only 0.2656 and it indicated that gene flow among populations of H.miconioides was relatively low.The mean value of the genetic identity among populations of H.miconioides was 0.7126 and the average of genetic distance of H.miconioides was 0.3412.The genetic identity between populations at the elevation of 990m and at the elevation of 780 m was the highest.The genetic identity between population at the elevation 500 m and other two populations was relatively low.The correlation analysis showed that the genetic diversity within populations was significantly related with the soil total nitrogen.     

Grain isozyme and ribosomal DNA variability in Hordeum spontaneum populations from Israel

Summary Grain isozyme and ribosomal DNA (rDNA) variability was examined in Hordeum spontaneum populations sampled from 27 geographical sites in Israel. Considerable phenotypic variability was observed with variants of ADH1, EST3, EST10, BMY1 and WSP detected, which are not available in the H. vulgare gene pool. Seven new rDNA phenotypes were detected in the H. spontaneum populations. Shannon's index of diversity was used to partition the total phenotypic variation into between and within population components. Most of the variation occurred between H. spontaneum populations. The distribution of both grain isozyme and rDNA phenotypes was non-random and correlated with a range of ecogeographical factors. In particular, the G phenotype of BMY1 was restricted to the Negev Desert and Dead Sea regions of Israel. Over 78% of the variation in the frequency of this particular phenotype could be explained by the number of rainy days per year and mean temperature in January. This suggests that variation at this locus or at loci linked to it may be of adaptive significance and of value in the introgression of genes controlling abiotic stress tolerance from H. spontaneum into the H. vulgare gene pool.     

Photosynthetic performance in wild emmer wheat,Triticum dicoccoides: ecological and genetic predictability

Summary In a twin study, we have shown that wild emmer wheat, Triticum dicoccoides, the progenitor of all cultivated wheats, harbours important genetic variation (Vg) in photosynthetic characteristics. This Vg resides within and between populations and ecogeographical regions in Israel, which is the center of origin and diversity of wild emmer wheat. Here we analyzed, by univariate and multivariate methods, the significant differentiation of variation in photosynthetic characteristics of 107 genotypes from 27 populations of wild emmer in Israel, distributed in three ecogeographical regions including central, xeric (northern cold and eastern warm) marginal, and mesic (western) marginal populations. The highest photosynthetic efficiency was displayed by populations of the xeric marginal region, but most variation for photosynthetic capacity occurs between accessions within ecogeographical regions and populations. Genotypes and populations of T. dicoccoides having high photosynthetic capacity can be identified by climatic factors and isozyme markers. The identification by genetic markers, if substantiated by testcrosses, can facilitate the maximization of conservation, in situ or ex situ, and utilization of these photosynthetic genetic resources for improvement of hexaploid wheat (T. aestivum).