Genetic diversity of durum wheat as determined by AFLP in fluorescence

The DNA of fifteen Italian cultivars of durum wheat (Triticum turgidum L. ssp. durum) were analyzed by in fluorescence amplified fragment length polymorphism (fAFLP) in order to obtain the characteristic fingerprintings of genotypes and assess their genetic relatedness. Among 64 combinations of fluorescence labelled primers, three different combinations were chosen as producing a total of 6630 AFLP fragments, 2277 (34.3 %) of them being polymorphic. By using this fAFLP methodology a DNA fingerprinting of each durum wheat cultivar was generated for genotype identification. Analysis of the genetic relationships show the low variability among durum wheat cultivars.     

Analysis of genetic diversity of spring durum wheat (Triticum durum Desf.) cultivars released in Russia in 1929-2004

Based on genealogical analysis, the genetic diversity of 78 spring durum wheat cultivars released in Russia in 1929-2004 have been examined. The temporal trends of change in diversity were studied using series of n x m matrices (where n is the number of the cultivars and m is the number of original ancestors) and calculating coefficients of parentage in sets of cultivars released in particular years. The pool of original ancestors of spring durum wheat cultivars includes 90 landraces and old varieties, more than a half (57%) of which originate from European countries, including Russia and Ukraine (45%). The original ancestors strongly differ in the frequency of presence in the cultivar pedigrees. Landraces Beloturka, Sivouska, Kubanka (T. durum Desf.), Transbaikalian emmer, Yaroslav emmer (T. dicoccum Schuebl.), Poltavka (T. aestivum L.), and the original ancestors of cultivars Kharkov 46, Narodnaya, and Melanopus 1932 enter in the pedigrees of more than half of cultivars created within the framework of various breeding programs. At that, their distribution by cultivars from different breeding centers strongly varies. Analysis of temporal dynamics of genetic diversity, based on genetic profiles and coefficients of parentage, has shown that the genetic diversity of Russian durum wheats increased during the period examined. Nevertheless, genetic erosion of the local material-a loss of approximately 20% of the pool of Russian original ancestors-has been found. The contribution of the original ancestors to the pedigrees of different cultivars, constructed in different breeding centers and recommended for cultivation in different regions, has been estimated. The variation of the released cultivars was highest in the Lower Volga region and lowest in the Ural region. In all, the lower threshold of genetic diversity in all regions does not reach the critical level, corresponding to the similarity of half-sibs. The set of modern cultivars included in the Russian Official List 2004 has a cluster structure.     

Relationships among durum wheat accessions. II. A comparison of molecular and pedigree information.

The study of direct ancestry relationships provides information with which to determine essential derivation. SSR profiles were used to determine the pattern of relatedness among 134 durum wheat accessions, representing the most important modern durum wheat gene pools. Simple sequence repeat (SSR)- and amplified fragment length polymorphism (AFLP)-based genetic similarities among cultivars with accurate pedigrees were compared with pedigree-based coefficients of parentage. Sizeable departures of molecular similarities from the expected ones were observed, indicating the unreliability of inferring the pattern of genetic relatedness from the coefficient of parentage. Case studies consisting of parent-progeny cultivar trios and pairs, identified on the basis of their registered pedigree, were studied to evaluate the probability of ancestry of each progeny cultivar, compared with all the remaining accessions. Rare alleles and haplotype sharing were also explored. When the results did not agree with the registered parentages, SSR markers provided information with which to identify the most probable parents (or the corresponding "breeding lineages") in the collection.     

Microsatellite analysis reveals a progressive widening of the genetic basis in the elite durum wheat germplasm

It has been argued that the level of genetic diversity in the modern durum wheat (Triticum turgidum L. var. durum) elite germplasm may have declined due to the high selection pressure applied in breeding programs. In this study, 58 accessions covering a wide spectrum of genetic diversity of the cultivated durum wheat gene pool were characterized with 70 microsatellite loci (or simple sequence repeats, SSRs). On average, SSRs detected 5.6 different allelic variants per locus, with a mean diversity index (DI) equal to 0.56, thus revealing a diversity content comparable to those previously observed with SSRs in other small-grain cereal gene pools. The mean genetic similarity value was equal to 0.44. A highly diagnostic SSR set has been identified. A high variation in allele size was detected among SSR loci, suggesting a different suitability of these loci for estimating genetic diversity. The B genome was characterized by an overall polymorphism significantly higher than that of the A genome. Genetic diversity is organised in well-distinct sub-groups identified by the corresponding foundation-genotypes. A large portion (92.7%) of the molecular variation detected within the group of 45 modern cvs was accounted for by SSR alleles tracing back to ten foundation-genotypes; among those, the most recent CIMMYT-derived founders were genetically distant from the old Mediterranean ones. On the other hand, rare alleles were abundant, suggesting that a large number of genetic introgressions contributed to the foundation of the well-diversified germplasm herein considered. The profiles of recently released varieties indicate that the level of genetic diversity present in the modern durum wheat germplasm has actually increased over time.Communicated by F. Salamini     

Arbitrarily primed-PCR based diversity assessment reflects hierarchical groupings of Indian tetraploid wheat genotypes

Genetic diversity analysis using PCR with arbitrary decamer primers (RAPD — random amplified polymorphic DNA) was carried out in a set of 63 tetraploid wheat genotypes which comprised 24 durum landraces, 18 durum cultivars, nine dicoccum cultivars, ten less commonly cultivated species and two wild tetraploid species. The durum and dicoccum wheat genotypes are a part of the germplasm used in Indian tetraploid wheat breeding programs. A total of 206 amplification products were obtained with 21 informative primers, of which 162 were polymorphic. The highest degree of polymorphism was seen in the wild and less commonly cultivated species (68.9%). Durum released cultivars showed greater polymorphism (50.6%) than landraces (44.8%), while dicoccum cultivars showed a considerably low level of polymorphism (23.6%). Cluster analysis led to the separation of wild and cultivated genotypes, and among cultivated emmer wheat distinct groups were formed by the durum cultivars, durum landraces and dicoccum cultivars. The subgroupings of landraces had no relation to their geographical distribution. The durum cultivars formed subgroups based on common parentage in their pedigree. Among species, wild timopheevi wheat (T. araraticum) and its cultivated form (T. timopheevi) formed a distinct group distant from all other genotypes. The present study is a first attempt at determining the genetic variation in Indian tetraploid wheats at the molecular level. Received: 10 January 1999 / Accepted: 30 January 1999     

Response of durum wheat cultivars to immature embryo culture,callus induction and in vitro salt stress

Response of twenty eight cultivars of durum wheat (Triticum turgidum var. durum) to immature embryo culture, callus production and in vitro salt tolerance was evaluated. For assessment of cultivars to salt tolerance, growing morphogenic calli were exposed to different concentrations of NaCl (0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8 and 2.1% w/v) added to the culture medium during two subsequent subcultures (4 weeks each). Comparison of cultivars for callus induction from immature embryo was based on callus induction frequency and fresh weight growth of callus (FWG). While, for salt tolerance, the relative fresh weight growth (RFWG) and necrosis percent of callus were used. There were significant differences among cultivars for potential of regeneration from immature embryo, and ‘Shahivandi’ a native durum wheat cultivar originating from western Iran was superior among the cultivars tested. The FWG distinguished cultivars more than callus induction frequency did for callus induction evaluation. Hence, a range of FWG from 1.23 to 14.65 g was observed in ‘Mexical-75’ and ‘Omrabi-5’ cultivars, respectively. Growing calli derived from cultivars ‘PI 40100’ and ‘Dipper-6’ showed superiority for tolerating salinity under in vitro conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nucleotide-binding site (NBS) profiling of genetic diversity in durum wheat.

Molecular markers are effective tools to investigate genetic diversity for resistance to pathogens. NBS (nucleotide-binding site) profiling is a PCR (polymerase chain reaction)-based approach to studying genetic variability that specifically targets chromosome regions containing R-genes and R-gene analogues. We used NBS profiling to measure genetic diversity among 58 accessions of durum wheat. Mean polymorphism rates detected using MseI and AluI as restriction enzymes were 34% and 22%, respectively. Mean number of polymorphisms per enzyme-primer combination was equal to 23.8 +/- 5.9, ranging from 13 to 31 polymorphic bands. In total, 96 markers over 190 indicated a good capacity to discriminate between accessions (the polymorphic index content ranging from 0.30 to 0.50). The results obtained with NBS profiling were compared with simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) data of the same set of accessions. The genetic distances computed with 190 NBS profiling markers were in close agreement with those obtained with AFLP and SSR markers (r = 0.73 and 0.76, respectively). Our results indicate that NBS profiling provides an effective means to investigate genetic diversity in durum wheat.     

AFLP analysis of genetic diversity within and among Coffea arabica cultivars

Genetic diversity of Coffea arabica cultivars was estimated using amplified fragment length polymorphism (AFLP) markers. Sixty one Coffea accessions composed of six arabica cultivars, including Typica, Bourbon, Catimor, Catuai, Caturra and Mokka Hybrid, plus two diploid Coffea species, were analyzed with six EcoRI- MseI primer combinations. A total of 274 informative AFLP markers were generated and scored as binary data. These data were analyzed using cluster methods in the software package NTSYSpc. The differences among cultivars at the DNA level were small, with an average genetic similarity of 0.933. Most accessions within a cultivar formed a cluster, although deviant samples occurred in five of the six cultivars examined due to residual heterozygosity from ancestral materials. Among the six cultivars fingerprinted, the highest level of genetic diversity was found within the cultivar Catimor, with an average genetic similarity of 0.880. The lowest level was found within Caturra accessions, with an average genetic similarity of 0.993. Diversity between C. arabica and two other Coffea species, Coffea canephora and Coffea liberica, was also estimated with average genetic similarities of 0.540 and 0.413, respectively, suggesting that C. canephora is more closely related to C. arabica than is C. liberica. The genetic variation among arabica cultivars was similar to the variation within cultivars, and no cultivar-specific DNA marker was detected. Although arabica cultivars appear to have a narrow genetic base, our results show that sufficient polymorphism can be found among some arabica cultivars with a genetic similarity as low as 0.767 for genetic/QTL mapping and breeding. The assessment of genetic diversity among arabica cultivars provided the necessary information to estimate the potential for using marker-assisted breeding for coffee improvement.     

Variation and classification of B low-molecular-weight glutenin subunit alleles in durum wheat

 The B low-molecular-weight (LMW) glutenin subunit composition of a collection of 88 durum wheat cultivars was analyzed. Extensive variation has been found and 18 different patterns were detected. Each cultivar exhibited 4–8 subunits, and altogether 20 subunits of different mobility were identified. The genetic control of all these subunits was determined through the analysis of nine F₂ populations and one backcross. Five subunits were controlled at the Glu-A3 locus, 14 at Glu-B3 and 1 at Glu-B2. At the Glu-A3 locus each cultivar possessed from zero to three bands and eight alleles were identified. At the Glu-B3 locus each cultivar showed four or five bands and nine alleles were detected. Only one band was encoded by the Glu-B2 locus. A nomenclature for these alleles is proposed and the relationship between them and the commonly used LMW-model nomenclature is discussed. Received: 10 February 1997 / Accepted: 25 April 1997     

Genetic relationships within Brassica rapa as inferred from AFLP fingerprints

Amplified fragment length polymorphism (AFLP) markers were employed to assess the genetic diversity amongst two large collections of Brassica rapa accessions. Collection A consisted of 161 B. rapa accessions representing different morphotypes among the cultivated B. rapa, including traditional and modern cultivars and breeding materials from geographical locations from all over the world and two Brassica napus accessions. Collection B consisted of 96 accessions, representing mainly leafy vegetable types cultivated in China. On the basis of the AFLP data obtained, we constructed phenetic trees using mega 2.1 software. The level of polymorphism was very high, and it was evident that the amount of genetic variation present within the groups was often comparable to the variation between the different cultivar groups. Cluster analysis revealed groups, often with low bootstrap values, which coincided with cultivar groups. The most interesting information revealed by the phenetic trees was that different morphotypes are often more related to other morphotypes from the same region (East Asia vs. Europe) than to similar morphotypes from different regions, suggesting either an independent origin and or a long and separate domestication and breeding history in both regions.     

A genetic linkage map of durum wheat

 A genetic linkage map of tetraploid wheat [Triticum turgidum (L.) Thell.] was constructed using segregation data from a population of 65 recombinant inbred lines (RILs) derived from a cross between the durum wheat cultivar Messapia and accession MG4343 of T. turgidum (L.) Thell. ssp dicoccoides (Korn.) Thell. A total of 259 loci were analysed, including 244 restriction fragment length polymorphisms (RFLPs), one PCR (polymerase chain reaction) marker (a sequence coding for a LMW (low-molecular-weight) glutenin subunit gene located at the Glu-B3 locus), seven biochemical (six seed-storage protein loci and one isozyme locus) and seven morphological markers. A total of 213 loci were mapped at a LOD≥3 on all 14 chromosomes of the A and B genomes. The total length of the map is 1352 cM and the average distance between adjacent markers is 6.3 cM. Forty six loci could not be mapped at a LOD≥3. A fraction (18.6%) of the markers deviated significantly from the expected Mendelian ratios; clusters of loci showing distorted segregation were found on chromosomes 1B, 3AL, 4AL, 6AL and 7AL. The durum wheat map was compared with the published maps of bread wheat using several common RFLP markers and general features are discussed. The markers detected the known structural rearrangements involving chromosomes 4A, 5A and 7B as well as the translocation between 2B-6B, but not the deletion on 2BS. This map provides a useful tool for analysing and breeding economically important quantitative traits and for marker-assisted selection, as well as for studies of genome organisation in small grain cereal species. Received: 5 January 1998 / Accepted: 31 March 1998     

Genetic Variation and Population Structure of Oriental Migratory Locust, Locusta migratoria manilensis, in China by Allozyme, SSRP-PCR, and AFLP Markers

Allozyme analysis, microsatellite primer PCR (SSRP-PCR), and amplified fragment length polymorphism (AFLP) techniques were used to assess genetic diversity and population structure of the Chinese oriental migratory locust, Locusta migratoria manilensis. A total of 299 PCR markers (67 SSRPs and 232 AFLPs) were detected in eight populations, of which 98.7% were polymorphic markers. The proportion of polymorphic loci (95.5–98.8%) by SSRP+AFLP markers indicated no significant differences between populations, and all populations exhibited a similar level of variability; results of the allozyme analysis demonstrated that 19 loci gave rise to a lower level of polymorphism (55.6–66.7%). The genetic distances between the populations were relatively low. Shannon’s index and Nei’s gene diversity showed low differentiation among the populations. Allozyme analysis, however, reflected greater similarity and smaller differentiation between the populations than those shown by SSRP and AFLP markers. Neighbor-joining dendrograms derived from both the allozyme and SSRP+AFLP markers showed that the genetic distances among Chinese oriental migratory locust populations were not greatly influenced by geographic distance and breeding habitats.     

Molecular mapping of stomatal‐conductance‐related traits in durum wheat (Triticum turgidum ssp. durum)

The most promising traits identified in wheat to raise yield potential via an increase in biomass accumulation are stomatal conductance and stomatal‐conductance‐related traits, such as carbon isotope discrimination (CID) and photosynthetic rate. The evaluation of the extent of genetic variation and the mapping of chromosomal regions controlling these traits are essential for the development of effective breeding strategies in durum wheat. A population of 161 F2‐derived, F8–F9 recombinant inbred lines obtained from a cross between durum wheat (Triticum turgidum ssp. durum) cultivars Ofanto and Cappelli was phenotyped for heading date, plant height, leaf porosity, CID and chlorophyll concentration (estimated through the SPAD index) for 2007/2008 and 2008/2009 seasons, at Ottava, Sardinia (Italy) under irrigated conditions. The genotype mean heritability for leaf porosity, CID and chlorophyll concentration was moderate in size. Six quantitative trait loci were detected for leaf porosity, four for chlorophyll concentration, but only one for CID, because of the small variation expressed in the population for this trait under these experimental conditions. The quantitative trait loci for leaf porosity located on chromosome 3B appear to be more stable with respect to the others, and different microsatellite markers are positioned within the interval of the quantitative trait loci, or in their vicinity, that represent useful tools in programmes for selection assisted by molecular markers.     

An AFLP-based survey of genetic diversity and relationships of major farmed cultivars and geographically isolated wild populations of <Emphasis Type="Italic">Saccharina japonica</Emphasis> (Phaeophyta) along the northwest coasts of the Pacific

The genetic diversity and relationships of six representative cultivars and six geographically isolated wild populations of Saccharina japonica along the northwest coasts of the Pacific Ocean were investigated using AFLP markers. A total of 547 bands were generated across all samples by ten primer combinations. At the cultivar or population level, the percentage of polymorphic loci (P), gene diversity (H), and Shannon’s information index (I) was highest in Dalian population (P 59.05%; H 0.2057; I 0.3062) and lowest in Lianjiang cultivar (P 9.87%; H 0.0331; I 0.0497). At the species level, P, H, and I were 85.01%, 0.1948, and 0.3096, respectively. Unique bands were detected in all the six wild populations, with Dalian being the most. In comparison, only Yanza cultivar possessed one unique band. The G _ST value was 0.6226 and the gene flow (N _m ) was 0.1515, indicating strong genetic differentiation among cultivars and populations. Two UMPGA dendrograms were constructed based on the Dice similarity coefficients among individuals and on genetic distances among cultivars and populations, which generally revealed three major clades corresponding to three countries. Analysis of molecular variance revealed that a larger proportion (60.21%) of the total genetic variation was attributable to differences among cultivars and populations. The Mantel test suggested that genetic differentiation was positively correlated with geographic distance (r = 0.7962, P = 0.011) in the six wild populations, agreeing with the isolation by distance model. On the whole, low to moderate genetic diversity within cultivars and populations (except Dalian population) and high genetic differentiation among cultivars and populations were detected.     

Analysis of genetic diversity in Glyptosternum maculatum (Sisoridae, Siluriformes) populations with AFLP markers

We determined the genetic diversity of geographic populations from three spawning grounds (Nyang River, Lhasa River, Shetongmon Reach of Yarlung Zangbo River) of Glyptosternum maculatum with amplified fragment length polymorphism (AFLP) markers. Five primer combinations detected 332 products, 51 of them (15.4%) were polymorphic in at least one population. The Shetongmon population was found to be the richest in genetic diversity as was indicated by the percentage of polymorphic loci and heterozygosity, followed by the Nyang population and the Lhasa population. The pair-wise genetic distance between populations were all very close, ranging from 0.0015 to 0.0042 with an average of 0.0024. The genetic distance was not proportional to the geographic distance. The analysis of molecular variance demonstrated that all variation occurred within populations. The average estimated fixation index (F _st) of three populations across all polymorphic loci was −0.0184, indicating the absence of genetic differences among the three sampled populations. The differentiation among populations was not significant, and population structure was weak. Our observations will help identify the genetic relationship among populations as the first approach to understand the genetic diversity of Glyptosternum maculatum.     

Molecular AFLP Analysis of the Genotypes of Pepper Capsicum annuum Cultivars

The results of AFLP study of 14 Capsicum annuum cultivars are presented. In spite of the known low genomic variation of large-fruited sweet pepper, AFLP analysis proved to be suitable for detecting polymorphism and genotyping pepper cultivars. Nine primer pairs were selected to allow identification of the cultivars under study. Among-cultivar polymorphism detectable with these primers was estimated at 16.5%. A characteristic AFLP pattern was obtained for each cultivar. Several cultivar-specific fragments were revealed for seven cultivars. On the basis of the AFLP data, genetic distances between cultivars were determined and a tree was constructed by means of hierarchic cluster analysis (UPGMA) with the Jacquard coefficient. It was assumed that this information is useful in breeding programs involving the cultivars examined.     

Analysis of hybrids of durum wheat with Thinopyrum junceiforme using RAPD markers

 The objective of this study was to detect the presence of alien chromatin in intergeneric hybrids of durum wheat (Triticum turgidum, 2n=4x=28; AABB genomes) with the perennial grass Thinopyrum junceiforme (2n=4x=28; J₁J₁J₂J₂) using RAPD markers. The first step was to identify amplification of species-specific DNA markers in the parental grass species and durum wheat cultivars. Initially, the genomic DNA of five grass species (Thinopyrum junceiforme, Th. bessarabicum, Lophopyrum elongatum, Leymus karataviensis and Elytrigia pycnantha) and selected durum cultivars (‘Langdon’, ‘Durox’, ‘Lloyd’, ‘Monroe’, and ‘Medora’) was screened with 40 oligonucleotide primers (nano-mers). Three oligonucleotides that amplified DNA fragments specific to a grass species or to a durum cultivar were identified. Primer PR21 amplified DNA fragments specific to each of the five durum cultivars, and primers PR22 and PR23 amplified fragments specific to each of the grass species. Intergeneric hybrids between the durum cultivars ‘Langdon’, ‘Lloyd’ and ‘Durox’ and Th. junceiforme, and their backcross (BC) progeny were screened with all 40 primers. Six primers amplified parent-specific DNA fragments in the F₁ hybrids and their BC₁ progeny. Three primers, PR22, PR23 and PR41, that amplified Th. junceiforme DNA fragments in both F₁ and BC₁ were further analyzed. The presence of an amplified 1.7-kb Th. junceiforme DNA fragment in the F₁ hybrids and BC₁ progeny was confirmed using Southern analysis by hybridization with both Th. junceiforme genomic DNA and Th. junceiforme DNA amplified with primer PR41. With the exception of line BC₁F₂ no. 5, five selfed progeny of BC₁ and a BC₂ of line 3 (BC₁F₂ no. 3בLloyd’) from a cross of ‘Lloyd’×Th. junceiforme showed the presence of the 1.7-kb DNA fragment. All selfed BC₁ and BC₂ lines retained the 600-bp fragment that was confirmed after hybridization with Th. junceiforme DNA amplified with primer PR22. Other experiments using RFLP markers also showed the presence of up to seven Th. junceiforme DNA fragments in the F₁ hybrids and their BC progeny after hybridization with Th. junceiforme DNA amplified with primer PR41. These studies show the usefulness of molecular markers in detecting alien chromatin/DNA fragments in intergeneric hybrids with durum wheat. Received: 21 November 1996 / Accepted: 21 March 1997     

Application of microsatellites in wheat (Triticum aestivum L.) for studying genetic differentiation caused by selection for adaptation and use

For studying genetic differentiation caused by selection for adaptation and end-use, the allele frequencies of 42 microsatellites (MS), representative of the three wheat genomes, were analysed in a total of 60 wheat cultivars. The cultivars originate from three agroecological areas (AEAs) – Germany, Austria and Hungary – and represent equal numbers of ’quality wheats’ and ’feed wheats’ for each country. For the 42 loci, 202 alleles were detected using PAGE and silver staining. The average number of alleles per locus was 4.8, including four monomorphic loci. For 16 loci, null alleles were detected. Cluster analysis clearly differentiated the varieties according to the three AEAs and, within each AEA, into quality wheats from feed wheats. Analysis of variance revealed highly significant differences of distance data between AEAs as well as between quality groups. The correlation between genetic distance (GD) and pedigree data (coefficient of diversity, COD) was r _s=0.45. The results have proven the excellent resolving power of MS in varietal differentiation, which arises through breeding under specific environmental conditions, and for different end-use. Received: 15 March 1999 / 17 June 1999     

Genetic diversity of modern Russian durum wheat cultivars at the gliadin-coding loci

The allelic diversity at four gliadin-coding loci was studied in modern cultivars of the spring and winter durum wheat Triticum durum Desf. Comparative analysis of the allelic diversity showed that the gene pools of these two types of durum wheat, having different life styles, were considerably different. For the modern spring durum wheat cultivars, a certain reduction of the genetic diversity was observed compared to the cultivars bred in the 20th century.     

Catalogue of alleles of gliadin-coding loci in durum wheat (Triticum durum Desf.)

Gliadins are seed storage proteins which are characterized by high intervarietal polymorphism and can be used as genetic markers. As a result of our work, a considerably extended catalogue of allelic variants of gliadin component blocks was compiled for durum wheat; 74 allelic variants for four gliadin-coding loci were identified for the first time. The extended catalogue includes a total of 131 allelic variants: 16 for locus Gli-A1(d), 19 for locus Gli-B1(d), 41 for locus Gli-A2(d), and 55 for locus Gli-B2(d). The electrophoretic pattern of the standard cultivar and a diagram are provided for every block identified. The number of alleles per family is quite small for loci Gli-A1(d) and Gli-B1(d) of durum wheat, as contrasted to loci Gli-A2(d) and Gli-B2(d) that are characterized by large families including many alleles. The presence of large block families determines a higher diversity of durum wheat for loci Gli-A2(d) and Gli-B2(d) as compared to Gli-A1(d) and Gli-B1(d). The catalogue of allelic variants of gliadin component blocks can be used by seed farmers to identify durum wheat cultivars and evaluate their purity; by breeders, to obtain homogenous cultivars and control the initial stages of selection; by gene bank experts, to preserve native varieties and the original biotypic composition of cultivars.