Identification of <Emphasis Type="Italic">Aegilops</Emphasis> L. species and <Emphasis Type="Italic">Triticum aestivum</Emphasis> L. based on chloroplast DNA

The genus Aegilops L. is a very important genetic resource for the breeding of bread wheat Triticum aestivum. Therefore, an accurate and easy identification of Aegilops species is required. Traditionally, identification of Aegilops species has relied heavily on morphological characters. These characters, however, are either not variable enough among Aegilops species or too plastic to be used for identification at the species level. Molecular markers that are more stable within species, therefore, could be the alternative strategy towards an accurate identification. Since the chloroplast DNA has a lower level of evolution compared to the nuclear genome, an attempt was made in this study to investigate polymorphism in the chloroplast DNA among 21 Aegilops species (including Ae. mutica that is now known as Amblyopyrum muticum) and between the latter and T. aestivum to generate markers for the diagnosis of all targeted species. Cleaved amplified polymorphic sequence (CAPS) applied on 22 coding and non-coding chloroplast regions using 80 endonucleases and sequencing of two of those regions revealed little polymorphism between T. aestivum and the various Aegilops species examined and to a less extent was the variation among Aegilops species. Polymorphism observed among species analysed allowed the discrimination of T. aestivum and 12 Aegilops species.     

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.     

Assessment of genetic diversity and relationships among <Emphasis Type="Italic">Triticum urartu</Emphasis> and <Emphasis Type="Italic">Triticum boeoticum</Emphasis> populations from Iran using IRAP and REMAP markers

Einkorn wheat is known as the donor of ‘A’ genome to cultivated wheat and source of many important genes. Therefore, genetic erosion in cultivated wheat provides a good reason to investigate genetic diversity in these species. In the present study, genetic diversity of 14 populations of Triticum urartu and Triticum boeoticum collected from west and north-west of Iran was examined by IRAP and REMAP markers. In total, 26 out of 36 IRAP and 41 out of 88 REMAP combinations amplified polymorphic and scorable banding patterns. IRAP and REMAP combinations produced 6.53 and 5.21 polymorphic bands per assay, respectively. Mean of polymorphism information content for IRAPs and REMAPs were 0.38 and 0.40 and marker index values for them were 2.60 and 2.09, respectively. Analysis of molecular variance based on IRAP and REMAP data revealed significant within and among population variances, although within population variance was higher than that of among population. Primer combinations based on Sukkula and Nikita retrotransposons produced the highest number of markers in the whole population. Cluster and principal coordinate analyses using REMAP data grouped the populations based on the species and geographical origin, but grouping based on IRAP could not separate the two species. However, based on both marker systems considerable diversity was observed among and within the studied populations.     

Genetic diversity trend of common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) in China revealed with AFLP markers

A total of 242 accessions of common wheat (Triticum aestivum L.) released in China since the 1940s were evaluated with AFLP (amplified fragment length polymorphism) technique. Genetic diversity was analyzed using five pairs of polymorphic primer combinations with 245 polymorphic bands. The highest genetic diversity was found in the accessions of the 1950s, and in the next place was that in the 1940s. The genetic diversity began to descend in the 1960s, and fell to the lowest in the 1970s. After that, the genetic diversity came back to some extent in the 1980s, however, it became much lower in the 1990s compared with that in the 1940–1950s. Landraces and introduced accessions from foreign countries showed greater genetic diversity in comparison to improved varieties. In addition, greater genetic diversity was observed in winter wheat. It was emphasized that great attention should be paid on further exploration of genetic diversity in wheat breeding program.     

Genetic diversity assessment of Bulgarian durum wheat (<Emphasis Type="Italic">Triticum durum</Emphasis> Desf.) landraces and modern cultivars using microsatellite markers

The genetic diversity in a Triticum durum Desf. collection, consisting of 102 Bulgarian landraces, nine Bulgarian and 25 introduced cultivars was studied using 14 highly polymorphic microsatellite markers. A total of 100 alleles were identified, with an average of 7.14 alleles per marker. The gene diversity values (He) of the markers for the total samples ranged from 0.23 (WMS357 and WMS631) to 0.77 (WMS46), with an average of 0.52. Within the landraces that were collected from 18 sites in Southern Bulgaria showed 2–11 alleles per locus with an average of 6.07. The microsatellite analysis suggests that the genetic diversity among landraces is lower compared to the diversity levels for durum wheat in countries close to the main centers of wheat domestication. Breeding activities have caused significant reduction of the allelic polymorphism, elimination of rare alleles, and increase in the number of common alleles and the frequency of dominating alleles.     

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.     

Genetic diversity of the D-genome in <Emphasis Type="Italic">T. aestivum</Emphasis> and <Emphasis Type="Italic">Aegilops</Emphasis> species using SSR markers

Simple sequence repeats (SSRs), highly dispersed nucleotide sequences in genomes, were used for germplasm analysis and estimation of the genetic relationship of the D-genome among 52 accessions of T. aestivum (AABBDD), Ae. tauschii (D^tD^t), Ae. cylindrica (CCD^cD^c) and Ae. crassa (MMD^cr1D^cr1), collected from 13 different sites in Iran. A set of 21 microsatellite primers, from various locations on the seven D-genome chromosomes, revealed a high level of polymorphism. A total of 273 alleles were detected across all four species and the number of alleles per each microsatellite marker varied from 3 to 27. The highest genetic diversity occurred in Ae. tauschii followed by Ae. crassa, and the genetic distance was the smallest between Ae. tauschii and Ae. cylindrica. Data obtained in this study supports the view that genetic variability in the D-genome of hexaploid wheat is less than in Ae. tauschii. The highest number of unique alleles was observed within Ae. crassa accessions, indicating this species as a great potential source of novel genes for bread wheat improvement. Knowledge of genetic diversity in Aegilops species provides different levels of information which is important in the management of germplasm resources.     

Genetic structure and history of Swiss maize (<Emphasis Type="Italic">Zea mays</Emphasis> L. ssp. <Emphasis Type="Italic">mays</Emphasis>) landraces

Between 1930 and 2003 with emphasis on the 1940s maize landraces (Zea mays L. ssp. mays) from all over Switzerland were collected for maintenance and further use in a new Swiss breeding program. The genetic relationship and diversity among these accessions stored in the Swiss gene bank is largely unknown. Our hypothesis was that due to the unique geographic, climatic, and cultural diversity in Switzerland a diverse population of maize landraces had developed over the past three centuries. The aims were to characterize the genetic diversity of the Swiss landraces and their genetic relationship with accessions from neighbouring regions as well as reviewing their history, collection, and maintenance. The characterization and grouping was based on analyses with ten microsatellite markers. Geographic, cultural, and climatic conditions explained a division in two distinct groups of accessions. One group consisted of landraces collected in the southern parts of Switzerland. This group was related to the Italian Orange Flints. The other group contained accessions from northern Switzerland which were related to Northern European Flints in particular German Flints. Historic evidence was found for a frequent exchange of landraces within the country resulting in a lack of region-specific or landrace-specific genetic groups. The relatively large separation between the accessions, indicated by high F _ST (0.42), might be explained partly by a bottleneck during the collection and maintenance phase as well as by geographical and cultural separation of north and south of the country. Due to the high genetic diversity, the accessions here are a potential resource for broadening the European flint pool.     

Stripe rust resistance in <Emphasis Type="Italic">Aegilops tauschii</Emphasis> and its genetic analysis

Aegilops tauschii Coss., the D-genome progenitor of common wheat (Triticum aestivum L.) includes two subspecies, tauschii and strangulata (Eig) Tzvel. Subspecies tauschii has a wide geographic distribution spreading westwards to Turkey and eastwards to Afghanistan and China, while ssp. strangulata has a narrower distribution occurring only in two disjoined regions, southeastern Caspian Iran and Transcaucasia. A collection of 56 Ae. tauschii accessions was screened at adult stage against a mixture of pathotypes of stripe rust prevalent in the current wheat production in China. The results for three crop seasons indicated that among the 38 ssp. tauschii accessions, 37 were susceptible and only one was resistant, while all the 18 ssp. strangulata accessions were resistant. These results indicated that stripe rust resistance was related to taxonomic origin. Further genetic analysis revealed the resistance of stripe rust in ssp. strangulata accession AS2388 was conferred by a single dominant gene.     

A haplotype specific to North European wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

A previous study indicated decreased DNA content of chromosome 4A in the wheat (Triticum aestivum L. cv. Tähti) compared to cvs. Chinese Spring and Rennan. Here we show that the lower 4A DNA content is associated with a specific haplotype in the distal part of 4AL. In 41 cultivars of bread wheat (T. aestivum L.), including cv. Tähti, a common haplotype was identified in the linkage disequilibrium region on the long arm of chromosome 4A (4AL). The haplotype (haplotype A) is characterized by 7 SSR and 5 EST marker alleles, including five zero-alleles. Haplotype A was found in 46 % of the Swedish/Finnish/Estonian spring wheat genotypes, while only one of the modern wheat accessions from Germany carried the same haplotype. Fluorescent cytometry analysis linked haplotype A to diminished DNA content of chromosome 4A. The haplotype was introduced into the Canadian and US breeding programs at the beginning of the twentieth century (cvs. Marquis, Thatcher, Ruby) from the common progenitor, the Polish landrace Fife, and it is still found in modern wheat germplasm in these countries. Zero-alleles characteristic for haplotype A were also detected in several accessions of European spelt (Triticum spelta L.), and in two accessions of tetraploid Triticum timopheevii Zhuk. The presence of haplotype A in European spelt indicates the considerable antiquity of the haplotype, as it must have been inherited from the hexaploid or tetraploid parent of spelt in at least one hybridization event.     

Exploitation of <Emphasis Type="Italic">Malus</Emphasis> EST-SSRs and the utility in evaluation of genetic diversity in <Emphasis Type="Italic">Malus</Emphasis> and <Emphasis Type="Italic">Pyrus</Emphasis>

A total of 8117 suitable SSR-contaning ESTs were acquired by screening from a Malus EST database, among which dinudeotide SSRs were the most abundant repeat motif, within which, CT/TC followed by AG/GA were predominant. Based on the suitable sequences, we developed 147 SSR primer pairs, of which 94 pairs gave amplifications within the expected size range while 65 pairs were found to be polymorphic after a preliminary test. Eighteen primer pairs selected randomly were further used to assess genetic relationship among 20 Malus species or cultivars. As a result, these primers displayed high level of polymorphism with a mean of 6.94 alleles per locus and UPGMA cluster analysis grouped twenty Malus accessions into five groups at the similarity level of 0.6800 that were largely congruent to the traditional taxonomy. Subsequently, all of the 94 primer pairs were tested on four accessions of Pyrus to evaluate the transferability of the markers, and 40 of 72 functional SSRs produced polymorphic amplicons from which 8 SSR loci selected randomly were employed to analyze genetic diversity and relationship among a collection of Pyrus. The 8 primer pairs produced expected bands with the similar size in apples with an average of 7.375 alleles per locus. The observed heterozygosity of different loci ranged from 0.29 (MES₉₆) to 0.83 (MES₁₃₈), with a mean of 0.55 which is lower than 0.63 reported in genome-derived SSR marker analysis in Pyrus. The UPGMA dendrogram was similar to the previous results obtained by using RAPD and AFLP markers. Our results showed that these EST-SSR markers displayed reliable amplification and considerable polymorphism in both Malus and Pyrus, and will contribute to the knowledge of genetic study of Malus and genetically closed genera.     

Gliadin Electrophoretic Analysis of the Genetic Integrity of Wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) Accessions After Frequent Seed Reproductions

A standard electrophoretic method for wheat cultivar identification was used on single seeds to analyse the genetic integrity of 11 wheat (Triticum aestivum L.) accessions after up to 24 seed reproductions in the Gatersleben genebank. It was clearly demonstrated that the gliadin pattern of single seeds can be used to analyse the genotype composition of wheat accessions. Stability of electrophoretic banding patterns was detected in eight accessions. Very week genetic drift was observed in three accessions. Our investigations confirm experiences of the successful utilisation of protein markers for cultivar verification and genetic integrity testing and demonstrate the high standard of wheat accessions maintenance in the Gatersleben genebank.     

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 Characterization of Brazilian Annual <Emphasis Type="Italic">Arachis</Emphasis> Species from Sections <Emphasis Type="Italic">Arachis</Emphasis> and <Emphasis Type="Italic">Heteranthae</Emphasis> using RAPD Markers

The genus Arachis is divided into nine taxonomic sections. Section Arachis is composed of annual and perennial species, while section Heteranthae has only annual species. The objective of this study was to investigate the genetic relationships among 15 Brazilian annual accessions from Arachis and Heteranthae using RAPD markers. Twenty-seven primers were tested, of which nine produced unique fingerprintings for all the accessions studied. A total of 88 polymorphic fragments were scored and the number of fragments per primer varied from 6 to 17 with a mean of 9.8. Two specific markers were identified for species with 2n = 18 chromosomes. The phenogram derived from the RAPD data corroborated the morphological classification. The bootstrap analysis divided the genotypes into two significant clusters. The first cluster contained all the section Arachis species, and the accessions within it were grouped based upon the presence or absence of the ‘A’ pair and the number of chromosomes. The second cluster grouped all accessions belonging to section Heteranthae.     

Divergent evolution of wild and cultivated subspecies of <Emphasis Type="Italic">Triticum timopheevii</Emphasis> as revealed by the study of <Emphasis Type="Italic">PolA1</Emphasis> gene

Triticum timopheevii (genome symbol AAGG) comprises two subspecies, cultivated ssp. timopheevii, and wild ssp. armeniacum. These two subspecies are considered as allotetraploids of AA genome from Triticum diploid species and SS genome from Aegilops species. The difference in genome symbol (G vs. S) is due to wide genetic variations among four SS genome species, Ae. bicornis, Ae. longissima, Ae. searsii, and Ae. speltoides. In order to study the origin of T. timopheevii, we compared 19th intron (PI19) sequence of the PolA1 gene, encoding the largest subunit of RNA polymerase I. Two different sized DNA fragments containing PI19 sequences (PI19A and PI19G) were amplified both in ssp. timopheevii and ssp. armeniacum. Shorter PI19A (112 bp) sequences of both subspecies were identical to PI19 sequences of two AA species, T. monococcum and T. urartu. Interestingly, the longer PI19G (241–243 bp) sequences of ssp. armeniacum showed more similarity to PI19 sequences of Ae. speltoides whereas ssp. timopheevii showed more similarity to PI19 sequences of other three SS genome species. The results indicated that two subspecies of T. timopheevii, ssp. armeniacum or ssp. timopheevii, might have arisen independently by allotetraploidization of AA genome with Ae. speltoides or one of the remaining three Aegilops species, respectively.     

Transfer of leaf rust and stripe rust resistance from <Emphasis Type="Italic">Aegilops umbellulata</Emphasis> Zhuk. to bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Aegilops umbellulata acc. 3732, an excellent source of resistance to major wheat diseases, was used for transferring leaf rust and stripe rust resistance to cultivated wheat. An amphiploid between Ae. umbellulata acc. 3732 and Triticum durum cv. WH890 was crossed with cv. Chinese Spring Ph ^I to induce homoeologous pairing between Ae. umbellulata and wheat chromosomes. The F₁ was crossed to the susceptible Triticum aestivum cv. ‘WL711’ and leaf rust and stripe rust resistant plants were selected among the backcross progenies. Homozygous lines were selected and screened against six Puccinia triticina and four Puccinia striiformis f. sp. tritici pathotypes at the seedling stage and a mixture of prevalent pathotypes of both rust pathogens at the adult plant stage. Genomic in situ hybridization in some of the selected introgression lines detected two lines with complete Ae. umbellulata chromosomes. Depending on the rust reactions and allelism tests, the introgression lines could be classified into two groups, comprising of lines with seedling leaf rust resistance gene Lr9 and with new seedling leaf rust and stripe rust resistance genes. Inheritance studies detected an additional adult plant leaf rust resistance gene in one of the introgression lines. A minimum of three putatively new genes—two for leaf rust resistance (LrU1 and LrU2) and one for stripe rust resistance (YrU1) have been introgressed into wheat from Ae. umbellulata. Two lines with no apparent linkage drag have been identified. These lines could serve as sources of resistance to leaf rust and stripe rust in breeding programs.     

Genetic diversity among <Emphasis Type="Italic">Jatropha</Emphasis> species as revealed by RAPD markers

The genus Jatropha is native of tropical America with more than 200 species that are widely distributed in tropics with a promise for use as an oil crop for biodiesel. This investigation was carried out to assess the genetic diversity of 12 Jatropha species based on random amplified polymorphic DNA markers. From 26 random primers used, 18 primers gave reproducible amplification banding patterns of 112 polymorphic bands out of 134 bands scored accounting for 80.2% polymorphism across the genotypes. Three primers viz., OPA 4, OPF 11, and OPD 14 generated 100% polymorphic patterns. The polymorphic information content was highest for the primer OPD 14 (0.50) followed by the primers OPF 11 and OPAD 11 (0.48). Jaccard’s coefficient of similarity varied from 0.00 to 0.85, indicative of high level of genetic variation among the genotypes studied. UPGMA cluster analysis indicated three distinct clusters, one comprising all accessions of J. curcas L., while second included six species viz., J. ramanadensis Ramam., J. gossypiifolia L., J. podagrica Hook., J. tanjorensis J. L. Ellis et Saroja J. villosa Wight and J. integerrima Jacq. J. glandulifera Roxb. remained distinct and formed third cluster indicating its higher genetic distinctness from other species. The overall grouping pattern of clustering corresponds well with principal component analysis confirming patterns of genetic diversity observed among the species. The result provides valid guidelines for collection, conservation and characterization of Jatropha genetic resources.     

Analysis of genetic diversity and relationships of wild <Emphasis Type="Italic">Guizotia</Emphasis> species from Ethiopia using ISSR markers

Genetic relationships and diversity of 45 Guizotia populations each consisting of ten individuals and belonging to five taxa of the genus Guizotia were analyzed using Inter Simple Sequence Repeat (ISSR) markers. Five ISSR primers generated a total of 145 scorable bands across the 450 individuals used for the study. The percent polymorphic loci for the taxa ranged from 68.2 (G. arborescens) to 88% (G. scabra ssp. schimperi), with G. scabra ssp. scabra, G. zavattarii and G. villosa following G. scabra ssp. schimperi in this order with respect to the abundance of percent polymorphic loci. The Shannon-Weaver diversity indices (H′), for the five taxa also followed a similar pattern, with G. scabra ssp. schimperi exhibiting the highest H′ (0.7373) and G. arborescens the least (0.5791), while H′ for G. scabra ssp. scabra, G. villosa and G. zavattarii were 0.7313, 0.6620 and 0.6564, respectively. The least genetic distance (0.1188) was observed between G. scabra ssp. schimperi and G.villosa, revealing closer genetic relationships of the two species with each other than with the others, and the highest genetic distance (0.2740) was observed between G. scabra ssp. schimperi and G. zavattarii. The unweighted pair group method using the arithmetic average clustering of the five taxa using the standard genetic distances produced two clusters, with G. scabra ssp. schimperi and G. villosa occurring in one cluster and G. scabra ssp. scabra, G. arborescens and G. zavattarii together in the other cluster. The study reveals that G. scabra ssp. schimperi is more closely related to G. villosa than to G. scabra ssp. scabra.     

Evaluating landraces of bread wheat <Emphasis Type="Italic">Triticum aestivum</Emphasis> L. for tolerance to aluminium under low pH conditions

Bread wheat (Triticum aestivum L.) landraces held within ex situ collections offer a valuable and largely unexplored genetic resource for wheat improvement programs. To maximise full utilisation of such collections the evaluation of landrace accessions for traits of interest is required. In this study, 250 accessions from 21 countries were screened sequentially for tolerance to aluminium (Al) using haematoxylin staining of root tips and by root regrowth measurement. The staining test indicated tolerance in 35 accessions, with an intermediate response to Al exhibited in a further 21 accessions. Of the 35 accessions classified as tolerant, 33 also exhibited increased root length following exposure to Al. The tolerant genotypes originated from Bulgaria, Croatia, India, Italy, Nepal, Spain, Tunisia, and Turkey. AFLP analysis of the 35 tolerant accessions indicated that these represent diverse genetic backgrounds. These accessions form a valuable set of germplasm for the study of Al tolerance and may be of benefit to breeding programs for expanding the diversity of the gene pool from which tolerant cultivars are developed.     

Resistance gene analog polymorphisms (RGAPs) in wild emmer wheat (<Emphasis Type="Italic">Triticum dicoccoides</Emphasis>) and their ecological associations

Using the 8 specific primer pairs based on the conserved motifs of plant resistance genes, the plant disease resistance gene analog polymorphisms (RGAPs) in 15 wild emmer wheat (Triticum dicoccoides) populations from Israel had been detected. High genetic variations at the RGAP loci were observed in T. dicoccoides populations. A total of 254 discernible bands were obtained among 115 accessions, and 192 bands (75.6%) were polymorphic. Each genotype had a unique banding profile, and the genetic similarity coefficient ranged from 0.094 to 0.862. In T. dicoccoides, the proportion of polymorphic loci (P), the genetic diversity (He) and Shannon’s information index were 0.756, 0.362 and 0.541, respectively. The proportion of polymorphic loci (P) per population averaged 0.732 (range: 0.515–0.932); genetic diversity (He) averaged 0.271 (range: 0.212–0.338); and Shannon’s information index averaged 0.404 (range: 0.310–0.493). The coefficients of genetic distance (D) among populations averaged 0.107 (range: 0.043–0.178), and the results of Mantel test (r = 0.168, P = 0.091) showed that the estimates of genetic distance were geographically independent. Neighbor-joining cluster analysis suggested that the genetic relationships of T. dicoccoides populations were associated with their ecogeographic distribution. The hierarchical analysis of molecular variance (AMOVA) and the coefficient of gene differentiation (G _ST ) values revealed that most of the variations were presented within populations, although significant differences among populations and regions were also detected. The values of P and Shannon’s information index were negatively correlated with the two factors: Tdd (day–night temperature difference) and Ev (mean annual evaporation), whereas they were positively correlated with one water factor: Rn (mean annual rainfall). The correlation matrix between He in the RGAPs and geographic variables contained 20 significant (P < 0.05) correlations. The present study established that T. dicoccoides in Israel had a considerable amount of genetic variations at RGAP loci at least partly correlated with ecological factors.