Genetic diversity in populations of wild diploid wheat Triticum urartu Tum. ex. Gandil. revealed by isozyme markers

Genetic variation and its distribution within and among 23 populations of Triticum urartu collected from Syria, Lebanon, Turkey, Armenia, and Iran was estimated using isozyme markers at eight polymorphic loci. The number of alleles per locus (A= 1.21), percentage polymorphic loci (P= 20.1%), and mean gene diversity (H_e= 0.024) were relatively low. In a population from Lebanon, a high number of alleles per locus (A= 2.13) and percentage polymorphic loci (P= 87.5%) was found. On average, genetic variation among populations (G_ST= 0.407) was smaller than within-population variation (0.593). However, different patterns of genetic structure were found among various geographic regions. Interpopulation variation was highest for the Iranian populations (0.89) followed by the Turkish populations (0.66). A reverse pattern was observed for the Syrian (0.11) and for the Lebanese (0.13) populations. The Armenian populations exhibited similar interpopulation and within-population variation. Principal component and cluster analyses resulted in distinct grouping of the geographically proximal populations, with the exception of the two Iranian populations. The Turkish populations were different from the neighboring Armenian populations compared to other countries. The populations from southern Syria and those from Lebanon also exhibited a high degree of genetic diversity. The two most heterozygous loci, Mdh-2 and Pgi-2, separated the populations along the first and second principal components, respectively. Most of the rare alleles were scattered sporadically throughout the geographic regions. Rare alleles with high frequencies were found in the Turkish and Armenian populations. These results indicated that different geographic regions require specific sampling procedures in order to capture the range of genetic variation observed in T. urartu populations.     

Comparison of the genetic structure of populations of wild emmer wheat, <Emphasis Type="Italic">Triticum turgidum</Emphasis> ssp. <Emphasis Type="Italic">dicoccoides</Emphasis>, from Israel and Turkey revealed by AFLP analysis

The aim of the present study was to assess the genetic variation in several Israeli and Turkish populations of wild emmer wheat, Triticum turgidum ssp. dicoccoides, the progenitor of most domesticated wheat. Single spikes were collected in 2002 from 60 plants that grew in six different habitats in Ammiad, northeastern Israel (8–12 plants from each habitat), and in 1998 from 56 plants that grew in seven different habitats in Diyarbakir, southeastern Turkey (8 plants from each habitat). Seeds were planted in a nursery and DNA was extracted from every plant and analyzed by the fluorescent-based amplified fragment length polymorphism (AFLP) method. Seven primer combinations produced 788 discernible loci of which 48.6% were polymorphic in Israel and 40.5% in Turkey. The genetic diversity estimates P (frequency of polymorphic loci) and He (gene diversity) were higher in Ammiad than in Diyarbakir (means of P = 0.34 and He = 0.13 in Ammiad vs. P = 0.20 and He = 0.08 in Diyarbakir). Ammiad populations contained more unique alleles than Diyarbakir populations. The relative genetic diversity estimates (θ) values were 0.188 in Ammiad and 0.407 in Diyarbakir, suggesting better differentiation of the populations in Turkey. Genetic distance was larger between Israeli and Turkish populations than between populations of each country. The data indicate that the Israeli and Turkish populations are considerably diverged and that the Israeli populations are more polymorphic than the Turkish ones, having a larger within-populations genetic variation than among-populations one. The significance of the results in relation to the differentiation pattern of wild emmer in the Near East is discussed.     

Genetic diversity of <Emphasis Type="Italic">Secale cereale</Emphasis> L. in Iran as measured using microsatellites

Microsatellite markers were used to analyse the genetic diversity of 120 individuals of 20 weedy/wild populations of Secale cereale collected all around Iran. High levels of diversity, with an average number of seven alleles per locus (ranging up to 11) and high level polymorphism with polymorphism rate averaging 0.645 (between populations) and 0.364 (within populations) were observed. The Northwestern populations showed the highest and the Northern populations showed the lowest polymorphism and diversity. One population was notably more similar to five of the S. strictum used as outgroups. No taxon or geographic specific marker was detected, suggesting high gene flow between the populations, however some groupings which can be related to the subspecies, were evident. This survey showed the high genetic diversity within the Iranian rye genepool as an important source for crop breeders, and indicated that there is value in sampling for useful genes for crops improvement.     

Isozyme polymorphism and genetic differentiation in natural populations of an endemic tetraploid species <Emphasis Type="Italic">Avena maroccana</Emphasis> in Morocco

A wild tetraploid oat Avena maroccana Gdgr. was collected from the 11 populations in the periphery of Rommani and Casablanca geographic groups of Morocco. Genetic diversity of the species was investigated using six allozyme systems. Allelic frequencies were scored representing eight polymorphic and five monomorphic loci. Coefficient of gene differentiation (Gst) was 0.3019, which indicated great genetic differentiation. The number of alleles per locus was 2.6154, the percentage of polymorphic loci was 61.54, and the expected heterozygosity was 0.2462 in all populations. Genetic diversity in A. maroccana was high in comparison to self-pollinated species. In total, nine heterozygotes resulting from outcrossing were found in the progeny from M1, M3, M4, M22 and M26. The population of M7 had peculiar alleles Pgd–2SS and Pgd-1SS in high frequency. M9 had the lowest level of diversity out of the 11 populations. Geographic and genetic distances between all the populations were not significantly correlated with each other (r = 0.0996). Cluster analysis showed that two groups, (M1, M22, M2 and M4) and (M3, M23, M8, M5 and M26) were apparently differentiated. Two populations of the Casablanca group, M7 and M9 were independent from each other, and were separated distinctly from the other populations. Genetic diversity of the Rommani and Casablanca groups was almost the same in all the parameters. This was due to the similar man-made habitat such as roadside or rich fertile soil and brown clay soils. The population size of A. maroccana was small and restricted to the narrow central Morocco with great genetic differentiation so that genetic diversity may be reflected from the results of genetic drift and outcrossing heterozygote segregation.     

Genetic diversity of HMW glutenin subunit in Chinese common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) landraces from Hubei province

The high molecular weight (HMW) glutenin subunit composition of 111 common landraces of bread wheat collected from Hubei province, China has been determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Ninety six of the accessions were homogeneous for HMW glutenin subunit composition and 15 were heterogeneous. For the Glu-1 loci, 16 alleles were detected, 3 at the Glu-A1locus, 9 at the Glu-B1and 4 at the Glu-D1. Three novel alleles were identified, two at the Glu-B1 and one at the Glu-D1locus. Combination of these 16 alleles resulted in 14 different HMW subunit patterns. The distribution of HMW glutenin subunit alleles in a subset of 105 of the 111 accessions representing six populations was assessed both at the individual population and whole population levels. The results demonstrated that the distribution of allelic patterns varied among populations. Taken together, 62.5% of the alleles detected were considered to be rare alleles while the Glu-A1c (null), Glu-B1b (1Bx7 + 1By8) and Glu-D1a (1Dx2 + 1Dy12) alleles were found most frequently in the six populations. The subset exhibited relatively high genetic diversity (A = 5.33, P = 1.00, Ae = 1.352 and He = 0.238) with 81.5% of the diversity being within populations and 18.5% between populations.     

Erratum to: Ecological,morphological and genetic diversity in <Emphasis Type="Italic">Oryza rufipogon</Emphasis> Griff. (Poaceae) from Hainan Island,China

In this study, ecological, morphological and genetic diversity in 11 surviving populations of Oryza rufipogon Griff. from Hainan Island, China were investigated. These data served to provide much needed data in support of conservation strategies. The results divided O. rufipogon into six ecotypes. The cluster analysis based on 19 morphological features showed clear differentiation among populations or within populations. The cluster analysis based on SSR also revealed similar results. The ecological, morphological and genetic diversity observed in O. rufipogon resulted in the following conservation recommendations: (1) the four currently protected O. rufipogon localities should be maintained, due to the different ecological communities represented at these sites; (2) some populations, such as HL (Hele county, Hainan Island), should be protected, but some populations, such as FC (Fucheng county, Hainan Island) and DL (Dalu county, Hainan Island), might not be protected. (3) An isolation zone should be established to avoid possible introgression between O. sativa L. and O. rufipogon; and human activities that impact O. rufipogon should be reduced or eliminated.     

Biodiversity of <Emphasis Type="Italic">Secale strictum</Emphasis> in Iran measured using microsatellites

The mountain rye Secale strictum is native to the Middle East and is the progenitor of the cultivated rye. Regarding lack of information about the genetic diversity of this species in Iran, this study was aimed to evaluate its genetic variation and to examine the patterns of diversity related to the varieties and geography. Fifteen wheat and rye derived microsatellite markers were used to achieve this aim. High levels of diversity, with an average number of 6.1 alleles per locus (ranging up to 11) and high level polymorphism with polymorphism rate averaging 0.624 (between populations) and 0.357 (within populations) were observed among 125 individuals from 19 populations collected from various regions of Iran. The Northwestern populations showed the highest and the Northern populations showed the lowest polymorphism and diversity. One population of the Northwest of the country was notably closer in its allele range to the S. cereale accessions used as outgroup. No taxon or geographic specific marker was detected, suggesting high gene flow between the populations, however some groupings which can be related to the geographic regions and varieties, were evident. The analysis of molecular variance attributed same portions of genetic diversity to the within and between populations with no significant variation among different geographic regions. The results of this study indicated that the Iranian genepool of Secale strictum is valuable to search for new useful alleles for crop improvement.     

Genetic variability in wild populations of <Emphasis Type="Italic">Prunus divaricata</Emphasis> Ledeb. in northern Iran evaluated by EST-SSR and genomic SSR marker analysis

A population genetic analysis based on eight genomic SSR markers and three EST-SSR (expressed sequence tags) markers developed in peach (Prunus persica (L.) Batsch) and Japanese plum (Prunus salicina Lindl.) was carried out in 12 wild populations of cherry plum (Prunus divaricata Ledeb.) sampled along the Iranian coast of the Caspian Sea. A total of 184 alleles (3–31 per locus) were detected with a mean value of 16.7 alleles per locus. None of the loci or populations showed deviation from Hardy–Weinberg equilibrium, and all markers proved to be unlinked. The mean values for the observed and the expected heterozygosity were 0.66 and 0.73, respectively. There was very little genetic differentiation among populations, as was indicated by low overall values of Wright’s F_ST (0.03) and Nei’s G_ST (0.08). An analysis of molecular variance (AMOVA) showed that 96.8% of the total variance was attributable to differences between individuals within populations. Genetic and geographic distances were nevertheless positively correlated, as evidenced by a Mantel test. The high level of genetic diversity and the apparent lack of genetic structure in wild P. divaricata may be attributed to frequent long distance gene flow through frugivorous birds and possibly humans, as has been documented for other Prunus species.     

Genetic diversity of <Emphasis Type="Italic">Guizotia abyssinica</Emphasis> (L. f.) Cass. (Asteraceae) from Ethiopia as revealed by random amplified polymorphic DNA (RAPD)

Genetic diversity of 70 populations of niger (Guizotia abyssinica) representing all its growing regions in Ethiopia was investigated using random amplified polymorphic DNA (RAPD) to reveal the extent of its populations genetic diversity. Ninety-seven percent of the loci studied was revealed to be polymorphic for the whole data set. The within population diversity estimated by Shannon diversity index and Nei gene diversity estimates was revealed to be 0.395 and 0.158, respectively. The extent of genetic variation of populations from major niger producing regions was significantly lower than that of populations from other regions; however, it is distributed regardless of altitude of growth. Genetic differentiation between populations was estimated with Shannon index as G^′ _ST (0.432), Nei’s G _ST (0.242) and AMOVA based F _ST (0.350) and appears to be equivalent to the average values calculated from various RAPD based studies on outcrossing species. Higher proportion of the variation detected by AMOVA resided within populations (64.58%) relative to the amount of variation among populations (35.42%). UPGMA cluster analysis showed that most of the populations were clustered according to their region of origin. However, some populations were genetically distant from the majority and seem to have unique genetic properties. It is concluded that the crop has a wide genetic basis that may be used for the improvement of the species through conventional breeding and/or marker assisted selection. Collection of germplasm from areas not yet covered and/or underrepresented is the opportunity to broaden the genetic basis of genebank collection.     

Exploration of glaucous variation in a collection of wild diploid wheat Triticum urartu Thumanjan ex Gandilyan

Glaucousness is the visible opaque-white or bluish-green wax which appears in plant cuticles. Although W1 and Iw1 loci on chromosome 2B mainly play a role to determine glaucousness/non-glaucousness trait in polyploid wheat, in the chromosome 2A of polyploid wheat, the non-glaucous inhibitor locus has not been reported. We explored the glaucous phenotypes for leaf, spike and stem in 274 accessions of Triticum urartu Thumanjan ex Gandilyan (2n?=?2x?=?14, genome A^uA^u), the A genome progenitor of polyploid wheat. The 272 accessions of T. urartu were non-glaucous for leaf, spike and stem. It was thought that non-glaucousness of T. urartu played an important role for plant adaptation throughout the Fertile Crescent. However, PI 662236 was glaucous in leaves, leaf sheaths and spikes, whereas PI 662271 was glaucous on the leaves and leaf sheaths, but non-glaucous in the spikes. Prior to heading PI 662236 and PI 662271 mimicked T. urartu by showing glaucous leaves and leaf sheaths. The plant form and somatic chromosome number indicated that PI 662236 and PI 662271 were tetraploid Triticum dicoccoides (Körn. ex Asch. & Graebn.) Schweinf. (2n?=?4x?=?28, BBA^uA^u genome). The occurrence of T. dicoccoides in the collections of T. urartu demonstrated that even famous botanists can make mistakes in identifying grasses. However, these mistakes lead to finding two rare types of T. dicoccoides with occurrence of glaucousness. The majority of T. dicoccoides that are non-glaucous. The genotype of PI 662236 was assigned as iw1iw1iw3iw3 for glaucousness and that of PI 662271 was iw1iw1Iw3Iw3 for the inhibitors for non-glaucous spikes.

     

RAPD-based Analysis of Genetic Diversity and Selection of Lingonberry (<Emphasis Type="Italic">Vaccinium vitis-idaea</Emphasis> L.) Material for <Emphasis Type="Italic">ex situ</Emphasis> Conservation

Random amplified polymorphic DNA markers were used to assess relatedness and genetic diversity for 15 lingonberry (Vaccinium vitis-idaea) populations. Seven primers yielding 59 polymorphic bands were used to analyse 13 populations, representing ssp. vitis-idaea from Sweden, Finland, Norway, Estonia and Russia, and two populations, representing ssp. minus from Japan and Canada. A cluster analysis and a multidimensional scaling analysis (MDS) showed similar phenetic patterns among populations, with a pronounced geographic grouping in most cases. Significant correlations were obtained between geographic and genetic distances for the entire set of populations as well as for the 13 ssp. vitis-idaea populations. Mean within-population diversity was 0.206 when estimated with Lynch and Milligan's index, and 0.431 when estimated with Shannon's index, which is in agreement with the mixed mating system reported for lingonberry. Within-population variability accounted for 68.6% of the total variance when all populations were included, and for 78.8% when only populations of ssp. vitis-idaea were analysed. Two different approaches were applied to the selection of plant material for a potential gene bank: (1) a hierarchical sampling strategy based on a cluster analysis and (2) the Maximum genetic diversity program, developed for the establishment of core collections. Random sampling was undertaken for comparisons with the selected data sets. The most diverse and representative set of lingonberry specimens was obtained when samples were selected with the Maximum diversity program.     

Genetic diversity in seven populations of Nicaraguan teosinte (<Emphasis Type="Italic">Zea nicaraguensis</Emphasis> Iltis et Benz) as estimated by microsatellite variation

Teosintes are the closest relatives to modern maize, Zea mays L. ssp. mays. They are wild grasses with a native distribution area from Mexico to Nicaragua and represent an important genetic resource. However, the genetic diversity of Nicaraguan teosinte (Zea nicaraguensis Iltis et Benz) has not yet been determined. This teosinte species has decreased in the last 25 years and now must be regarded as an endangered species. An analysis of the genetic diversity of Zea nicaraguensis was carried out in a total of 240 individuals from seven populations. Eleven Simple Sequences Repeat (SSR) primer pairs were used. A total of 42 alleles were found, the range of alleles per locus was 2–5 (mean 3.8) and the numbers of genotypes varied between primers. The primer Bnlg 1538 showed the highest value, with 45 genotypes through all populations. The genetic diversity observed (Ho) between all populations varied from 0.51 to 0.63, with an average of 0.563. One of the populations had as many as 40 alleles. Analysis of molecular variance (AMOVA) revealed that most of the variation was within population, at a significantly high level (P < 0.001). Rare alleles were detected in all populations, but unique alleles were only found in four populations. These results are highly relevant when developing conservation strategies and show that preserving populations in their natural habits is highly important.     

Gliadins of Bulgarian durum wheat (<Emphasis Type="Italic">Triticum durum</Emphasis> Desf.) landraces: genetic diversity and geographical distribution

The polymorphism of gliadins was studied in 98 Bulgarian durum wheat (Triticum durum Desf.) landraces and classified according to the existing catalogues of blocks of gliadin components. In total, 31 alleles, including 12 new ones, were revealed for five gliadin-coding loci. Nine allele families, which included several alleles coding similar blocks differed only by minor components, were found. The gliadin loci had a high genetic diversity (H = 0.70), and Gli-A2 ^d was the most polymorphic locus. Significant differences in allele distribution were observed through the Bulgarian region under study. The results made it possible to explain the distribution by historical factors. Presumably, the genetic material flew into the country via two different ways and different durum wheat subgroups contributed to the formation of Bulgarian landraces. The landraces were a result of long-term selection and, probably, had a close association with the history of the human populations of the region.     

Assessment of genetic variability in hexaploid wheat landraces of Pakistan based on polymorphism for HMW glutenin subunits

Summary Sixty hexaploid wheat landraces collected from five regions of Pakistan were assessed for genetic variability in terms of high molecular weight (HMW) glutenin subunits as revealed by SDS-PAGE. The germplasm appeared to be diverse and unique on the basis of HMW glutenin subunit compositions. Out of 24 alleles detected at all the Glu-1 loci, four belonged to Glu-A1, 12 to Glu-B1 and eight to Glu-D1 locus. The number of novel HMW glutenin subunits detected were 1, 4 and 6 at the three loci (Glu-A1, Glu-B1, Glu-D1), respectively. The frequency distribution patterns of 24 allelic variants detected at the three Glu-1 loci in 1080 samples analysed for 60 accessions were determined both on the basis of individual accessions and on the basis of regions (accessions pooled across the regions). One allele (null) at the Glu-A1 locus, three alleles (17+18, 7+8, 14) at the Glu-B1 locus and, two alleles (2+12 and 2^**+12) at the Glu-D1 locus were found most frequently distributed in the 60 populations. Maximum variation was observed in the Baluchistan and Gilgit regions of Pakistan in terms of distribution of novel Glu-1 alleles. A higher gene diversity was observed between the populations as compared to the gene diversity within the populations while, a reverse pattern of gene diversity was observed when populations were pooled across the regions (higher within the regions than between the regions). A data base has been generated in this study which could be expanded and usefully exploited for cultivar development or management of gene bank accessions.     

Isozyme studies of genetic diversity and evolution in Hippophae

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.     

Genetic diversity of Curcuma alismatifolia Gagnep.(Zingiberaceae) in Thailand as revealed by allozymepolymorphism

Allozyme polymorphism at seven loci (TPI, G6PD-2,IDH-1, SKD-2, MDH-1, GOT-1, andGOT-2) was employed to detect the level of geneticdiversity in C.alismatifolia populations from both cultivatedand wild habitats in Thailand. High diversity was observed in allpopulations with relatively lower values in cultivated populations.Percentage of polymorphic loci (P)varied from 85.7–100% in cultivated populations comparedwith 100% in all natural populations. Allele number per locus(A _L) was 3.14 in cultivatedpopulations, and from 2.86–4 in natural populations. Allelenumber per polymorphic locus(A _P) of cultivated andnatural populations ranged from 3.14–3.5 and 2.86–4,respectively. Genetic diversity within populations(H _S) varied from0.586–0.611 in cultivated and from 0.621–0.653 in naturalpopulations. The genetic identity(I _SP) for the species was0.833. The cultivated populations yielded higher value of geneticidentity with highland populations(I _{C /H} =0.776) than with the lowland ones(I _{C /L} =0.754). The analysis of genetic similarities with theNeighbor-Joining algorithm results in the separation ofcultivated populations from all wild populations. One highlandpopulation from the tourist spot, H2, was placed in a separatecluster between the cultivated and other wild populations. It isconsidered as the possible origin of the cultivatedpopulations.     

绿色豌豆蚜不同地理种群的遗传多样性

豌豆蚜是我国苜蓿上危害最为严重的害虫之一。利用微卫星标记研究了我国绿色型豌豆蚜10个地理种群的遗传相似性、基因分化、遗传距离与地理距离和海拔之间的关系及其基因结构。选取15对引物扩增300个个体,共检测到41个多态性条带,多态性条带百分率(PPB)为100%。10个豌豆蚜地理种群观测等位基因数(Na)为1.592 7,有效等位基因数(Ne)为1.356 9,Nei’s基因多样性指数为0.206 6,Shannon-Wiener指数(I)为0.307 6。新疆维吾尔自治区、陕西省、河南省种群的遗传多样性较高,内蒙古自治区、山东省、青海省种群相对较低。然而,10个地理种群豌豆蚜(绿色型)的遗传分化较高(Gst=0.399 6)。种群聚类分析结果显示,全部豌豆蚜种群明显聚为两大类群,山东省、河南省种群为一大类群,其余为另一大类群。Mentel检测表明,遗传分化与地理距离、海拔无显著相关性。我国豌豆蚜种群具有非常丰富的遗传多样性,应加强豌豆蚜的监测和治理。     

Genetic diversity and gene-pool subdivisions of diploid D-genome <Emphasis Type="Italic">Aegilops tauschii</Emphasis> Coss. (Poaceae) in Iran as revealed by AFLP

The diploid goatgrass Aegilops tauschii is considered the D-genome donor of bread wheat and has probably a centre of diversity in north of Iran. In order to measure the genetic diversity of and the relationships among different populations, varieties and subspecies belonging to Ae. tauschii in Iran, DNA was extracted from 48 accessions of Ae. tauschii collected across the geographic range of the species in the Country and the genetic diversity was assessed using AFLPs based on eight PstI/MseI +3 primer pairs resulted in 277 bands, 198 of which were polymorphic. High level polymorphism was detected, with an average of polymorphism rate of 0.715; relatively low genetic similarity (0.455) between accessions and significant difference between the lowest (0.179) and the highest genetic similarity (0.817). The Iranian Ae. tauschii populations showed high level of genetic diversity. The populations studied were divided into two groups: one group was mainly representing Northern populations collected from Southern Caspian Sea shore and the other group was mainly representing Northeast and Northwest populations. Based on the results of this study, it can be suggested that Ae. tauschii possesses two separate gene-pools in Iran: Northern and Northeastern–Northwestern. Considering the needs for introducing new characteristics and alleles for wheat improvement purposes, Ae. tauschii Iranian gene-pool is assumed to be of high importance for more investigation in the future.     

Genetic variability in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) of Pakistan based on polymorphism for high molecular weight glutenin subunits

Variation in bread wheat including pre and post green revolutions varieties of Pakistan along with landraces was investigated for high molecular weight Glutenin subunits (HMW Gs) encoded at three genes (Glu-A1, Glu-B1, Glu-D1) with SDS-PAGE. The germplasm was diverse and unique on the basis of HMW Gs compositions and out of 14 alleles detected at all the Glu-1 loci, three belonged to Glu-A1, nine to Glu-B1 and two to Glu-D1 locus. High variation was observed in the landraces and higher gene diversity was observed between the populations as compared to the gene diversity within populations, whereas a reverse pattern of gene diversity was observed when populations were pooled across the region (higher within the regions than between the regions). A lack of relationship between the HMW Gs diversity and the altitude of collection site was observed. A data base has been generated in this study which could be expanded/exploited for cultivar development or management of gene bank.     

The genetic characterization of Turkish watermelon (<Emphasis Type="Italic">Citrullus lanatus</Emphasis>) accessions using RAPD markers

Genetic diversity of the Turkish watermelon genetic resources was evaluated using different Citrullus species, wild relatives, foreign landraces, open pollinated (OP) and commercial hybrid cultivars by RAPD markers. The germplasm was consisted of 303 accessions collected from various geographical regions. Twenty-two of 35 RAPD primers generated a total of 241 reproducible bands, 146 (60.6%) of which were polymorphic. Based on the RAPD data the genetic similarity coefficients were calculated and the dendrogram was constructed using UPGMA (Unweighted pair-group method with arithmetic average). Cluster analysis of the 303 accessions employing RAPD data resulted in a multi-branched dendrogram indicating that most of the Turkish accessions belonging to var. lanatus of Citrullus lanatus (Thunb.) Matsum et Nakai were grouped together. Accessions of different Citrullus species and Praecitrullus fistulosus (Stocks) Pangalo formed distant clusters from C. lanatus var. lanatus. Among 303 accessions, a subset of 56 accessions was selected representing different groups and a second dendrogram was constructed. The genetic similarity coefficients (GS) within the Turkish accessions were ranged from 0.76 to 1.00 with 0.94 average indicating that they are closely related. Taken together, our results indicated that low genetic variability exist among the watermelon genetic resources collected from Turkey contrary to their remarkable phenotypic diversity.