Durum Accessions Research Articles

The Bo1-specific PCR marker AWW5L7 is predictive of boron tolerance status in a range of exotic durum and bread wheats

High soil boron (B) constitutes a major soil problem in many parts of the world, particularly in low-rainfall areas and land under irrigation. Low accumulation of B in the shoot or grain of cereal crops is correlated with the maintenance of biomass production and grain yield under high B conditions, suggesting that this trait is an important component of field tolerance. A novel screening protocol to measure B accumulation in aerated and supported hydroponics was validated using a set of known and exotic bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. subsp. durum (Desf.) Husn.) accessions. Furthermore, B accumulation in two Triticum urartu Tumanian ex Gandilyan and 54 Triticum monococcum L. accessions was measured and showed considerable phenotypic variation. However, B accumulation in these lines was higher than that observed in the most tolerant durum or bread wheats. Mapping of high B tolerance in the durum population AUS14010/Yallaroi revealed a locus possibly allelic to Bo1, a major source of B toxicity tolerance previously identified in bread wheat. Here, we show that the Bo1-specific codominant PCR marker AWW5L7 is predictive of B tolerance status among exotic durum and bread wheat accessions. All tolerant durum accessions assayed carried very similar AWW5L7 marker fragments, indicating wide distribution of this allele among tolerant durum wheats. Three bread wheat accessions had tolerance that was independent of Bo1 and is probably located on chromosome 4A. These lines represent a valuable genetic resource for B toxicity tolerance breeding in wheat.

An integrated DArT-SSR linkage map of durum wheat

Genetic mapping in durum wheat (Triticum durum Desf.) is constrained by its large genome and allopolyploid nature. We developed a Diversity Arrays Technology (DArT) platform for durum wheat to enable efficient and cost-effective mapping and molecular breeding applications. Genomic representations from 56 durum accessions were used to assemble a DArT genotyping microarray. Microsatellite (SSR) and DArT markers were mapped on a durum wheat recombinant inbred population (176 lines). The integrated DArT-SSR map included 554 loci (162 SSRs and 392 DArT markers) and spanned 2022 cM (5 cM/marker on average). The DArT markers from durum wheat were positioned in respect to anchor SSRs and hexaploid wheat DArT markers. DArT markers compared favourably to SSRs to evaluate genetic relationships among the durum panel, with 1315 DArT polymorphisms found across the accessions. Combining DArT and SSR platforms provides an efficient and rapid method of generating linkage maps in durum wheat.

Evaluation of wheat germplasm from the Madeira and Canary archipelagos using a single molecular marker. A rapid screening method for identification of durum wheat accessions

This work aims to present a rapid and precise screening method of wheat germplasm and identification of durum wheat accessions in germplasm collections. Fifty-two wheat accessions maintained in the ISOPlexis germplasm bank at the Madeira University, Portugal, and 72 accessions from the Centre for Conservation of Crop Biodiversity of Tenerife (CCBAT), Spain, have been screened for their specific ploidy status using the molecular marker Dgas44. We have demonstrated that the Dgas44 sequence is effective in the screening of Madeiran and Canarian wheat accessions. This screening method permitted the detection of 10 and 11 durum accessions among Madeiran and Canarian wheats, accounting for 19.2 and 15.3% of screened collections, respectively. The obtained results have shown a 100% of cases correspondence with the previously performed morphological identification of the Madeiran wheats. It also permitted rectification and clarification of previous classification of some accessions based only on the morphological traits. The PCR based assay was directly applicable to the screening of seeds and was suitable for detecting seed mixtures in accessions. This rapid method has been proven to be a useful tool in gene bank accessions management including verification of their ploidy status and detection of seed lots adulteration.

Isolation and Analysis of α-Gliadin Gene Coding Sequences from Triticum durum

Three coding sequences of gliadins genes, designed as Gli2_Du1, Gli2_Du2 and Gli2_Du3, were isolated from the genomic DNA of Triticum durum accessions CItr5083. Gli2_Du1 and Gli2_Du2 contain 945 and 864 bp, encoding the mature proteins with 314 and 287 amino acid residues, respectively. Gli2_Du3 is recognized as a pseudogene due to the stop codon occurring in the coding region. The pseudogenes, commonly occurring in gliadins family, are attributed to the single base change C → T. The amino acid sequences deduced from these gene sequences were characterized with the typical structure of α-gliadin proteins, including the toxic sequences (PSQQQP). The peptide fraction PF(Y)PP(Q) is thought to be an extra unit of repetitive domain, slightly diverging from the previous report. Six cysteine residues were observed within two unique domains. Phylogenetic analysis showed Gli2_Du2 and Gli2_Du3 were closely related to the genes on chromosome 6A, whereas Gli2_Du1 seems to be more homologous with the genes on chromosome 6B.

Sources of Resistance to Stem Rust (Puccinia graminis f. sp. tritici) in Ethiopian Tetraploid Wheat Accessions

Seedlings of 41 emmer (Triticum dicoccon Schrank) and 56 durum (T. durum Desf.) wheat accessions were evaluated for their response to stem rust (Puccinia graminis f. sp. tritici) infection under greenhouse condition at Kulumsa Agricultural Research Center, Ethiopia. The objectives were to identify tetraploid wheat accessions that could serve as sources of resistance to stem rust, and postulate the stem rust (Sr) resistance genes through multipatotype testing. The test included screening of accessions for stem rust resistance and multipatotype testing. To ensure vigorous screening, a mixture of six isolates (Si-1a, Am-2, Ku-3, Dz-4a, Ro-4 and Na-22) that were collected from severely infected emmer, durum, and bread wheat (Triticum aestivum L.) varieties of major wheat growing areas of Ethiopia was used as inocula. Out of the tested accessions, 18 emmer and 6 durum accessions exhibited low infection types (0–2) response and hence selected as a source of resistance to stem rust infection. Multipatotype testing was done to postulate Sr genes in the selected accessions. In the test, 10 different stem rust races (A2, A9, A11, A14, A16, A17, B3, B7, B15, and B21), 33 stem rust differential lines, and a universal susceptible check variety, Morocco were used, The high (3–4) and low infection type reaction patterns of the tested accessions and differential lines were used to postulate the genes that exhibit gene-for-gene relationship. The presence of Sr 7b, 8b, 9a, 9b, 10, 14, 24, 27, 28, 29, 30, 31, 32 and Tt-3+10 genes were postulated in 16 selected emmer and 5 durum wheat accessions. Efforts to transfer these valuable Sr genes from cultivated tetraploid wheats could be rewarding to get stem rust resistant varieties and boost wheat production.

A panel of elite accessions of durum wheat (Triticum durumDesf.) suitable for association mapping studies

The effectiveness of association mapping (AM) based on linkage disequilibrium (LD) is currently being tested in a number of crops. An important prerequisite for the application of AM is the availability of collections of accessions with a suitable level of genetic variation for target traits and with limited spurious LD due to the presence of population structure. Herein, the results of a genome-wide molecular characterization of a collection of elite durum wheat accessions well-adapted to Mediterranean environments are presented. Ninety-seven highly polymorphic simple sequence repeats and 166 amplified fragment length polymorphism markers were used to characterize 189 durum accessions, mainly cultivars and advanced breeding lines. Genome-wide significant and sizeable LD indices at a centimorgan scale were observed, while LD mainly decayed within 10 cM. On the other hand, effects due to spurious LD were notably lower than those previously observed in a durum wheat collection sampling durum gene pools of more diverse origin. These results, coupled with the high level of genetic variability detected for a number of important morpho-physiological traits and their high heritability, indicate the suitability of this collection for AM studies targeting agronomically important traits.

The occurrence and inheritance of a brittle rachis phenotype in Italian durum wheat cultivars

Italian and Tunisian durum wheats from different eras of breeding were assessed for the presence of a gene for brittle rachis. Nine of 15 Italian durum landraces had brittle rachides. Strampelli’s achievement was the release of the well-known variety, Senatore Cappelli, which was derived from a Tunisian landrace, Jenah Rhettifah, which has a brittle rachis. Rachides of two Tunisian landraces were also brittle. Since the 1950’s, 16 accessions were released as selections from crosses or mutagenesis involving Senatore Cappelli. Seven of these accessions have brittle rachides. F2 segregation in intercrosses of Senatore Cappelli with other durum accessions with brittle rachides indicated a common allele for brittle rachis. Segregation of the F2 from Senatore Cappelli/ANW 10A and the F2 of Senatore Cappelli/ANW 10B showed that the gene for brittle rachis of Senatore Cappelli was allelic to the brittle allele of the Br-B1 locus on chromosome 3B. Senatore Cappelli was presumably the only source of brittle rachis used in Italian breeding programmes. The genes for brittle rachis have been retained in the gene pool of durum wheat, suggesting that the brittle rachis character is not associated with an appreciable yield loss in modern farming systems in Mediterranean environments.

New durum wheat with Hessian fly resistance from Triticum araraticum and T. carthlicum in Morocco

AbstractHessian fly is an important pest of wheat on the North American continent and the temperate Mediterranean drylands. Yield losses caused by this insect in Morocco are the heaviest in the Mediterranean region and are estimated to be 36% on average. Genetic resistance to Mediterranean Hessian fly biotypes has not been found in durum wheat, although large numbers of durum accessions were screened. Genes for resistance were found in common wheat; some of which are transferable to durum. However, there is a need to broaden the genetic base for resistance in durum wheat. The objective of this work was to introgress resistance from selected Triticum araraticum and T. carthlicum accessions using multiple backcross methodology. The experimental recipient durum wheat included numerous adapted and high‐yielding lines. Testing for Hessian fly resistance under controlled conditions and field yield data showed that this programme yields Hessian fly‐resistant durum lines with good yields and adaptation.

Variation for apparent amylose content of endosperm starch in Triticum durum and Aegilops squarrosa

For breeding to increase amylose content in the starch of hexaploid wheat, either the introduction of genes from Aegilops squarrosa (DD genome) or the development of high-amylose amphiploids between Triticum durum (AABB genome) and Ae. squarrosa is one of the most efficient ways. The high-amylose genes have not been detected in any species of Triticum and Aegilops. Therefore, we assessed the apparent amylose content in endosperm starch of T. durum and Ae. squarrosa accessions supplied from the major gene banks from world wide, and found several accessions with higher amylose content out of 665 T. durum accessions and out of 732 Ae. squarrosa accessions. Genetic analysis indicated that a high amylose trait in Ae. squarrosa is monogenically inherited by a recessive major gene.

Polymorphism of two waxy proteins in the emmer group of tetraploid wheat, Triticum dicoccoides, T. dicoccum, and T. durum

AbstractGel‐electrophoretic analyses detected polymorphism of two waxy (Wx) proteins, Wx‐Al and Wx‐Bl, in 334 accessions of the emmer group of tetraploid wheat, Triticum dicoccoides, T. dicoccum and T. durum. The null allele for the Wx‐Al protein (Wx‐Alb) was found in one accession of T. dicoccoides and seven of T. dicoccum, but it was not present in those T. durum accessions analysed. The null allele for the Wx‐Bl protein (Wx‐Blb) did not occur in three emmer‐wheat species. Wx‐Al and Wx‐Bl proteins showing alteration in mobility in SDS‐PAGE gel or in isoelectric points were found in five accessions and considered to be the products of new alleles, Wx‐Ald, Wx‐Ale and/or Wx‐Bld. Densitometric analysis of Wx protein bands revealed that Wx‐Al was present in smaller amounts than Wx‐B1 in almost all accessions.

Triticum tauschii: reaction to the take-all fungus (Gaeumannomyces graminis var. tritici)

Reactions of 398 accessions of Triticum tawchii to the take-all fungus [Gaeumannomyces graminis var. tritici (Ggt] were assessed. Nineteen accessions were selected for more detailed studies. T. tauschii accessions were identified that had less tissue blackening and more remaining green tissue when challenged by the fungus than the susceptible T. aestivum cv. Condor. However, tissue blackening in the T. tauschii accessions was much greater than that in Avena sativa cv. New Zealand Cape. Synthetic allohexaploid wheats produced from different Triticum turgidum var. durum (genome AABB) accessions and accessions of T. tauschii (genome DD) which had low tissue blackening or high remaining green tissue had more tissue blackening and less remaining green tissue than the T. tauschii parents. The potential of this material for breeding take-all resistant wheats together with experimental methods to minimize the possible confounding effects of seed weight, seed source and genetic effects are discussed.

Comparison of Hungarian Winter Durum Wheat to Ohio Soft Red Winter Wheat

The opening of a new durum wheat (Triticum turgidum L. var. durum) mill in Ohio and the premium prices paid for durum led to an examination of the feasibility of successfully producing Hungarian winter durum wheat in Ohio and the rest of the soft red winter reheat (Triticum aestivum L.) (SRWW) region. The grain yields and agronomic characteristics of three promising Hungarian winter durum wheat cultivars, 'Basa', 'Minaret', and 'Pannondur', were compared to those of Ohio SRWW cultivars, 'Cardinal' and 'Dynasty', in seven field trials from 1989 to 1991, at Wooster, OH. Mean Hungarian winter durum grain yields were 20%, 48%, and 53% of Ohio SRWW in 1989, 1990, and 1991, respectively. Mean plant densities for the Hungarian durums improved from 49% in 1989, to 71% and 93% in 1990 and 1991, respectively [...]

FREEZING HARDINESS OF SOME ACCESSIONS OF Triticum tauschii AND T. turgidum L. var. durum

The objective of this study was to determine the variation for high- and low-intensity freezing resistance in 51 accessions of Triticum tauschii (Coss.) Schmal. and 35 accessions of T. turgidum L. var. durum. Freezing resistance ranged from non-hardy to as hardy as T. aestivum ’Winoka’ for T. tauschii under both the high- and low-intensity freeze test. Although the T. turgidum var. durum accessions were less hardy than Winoka in the high intensity test, some accessions of this species approached the hardiness of Winoka in the low-intensity test. This suggests that T. tauschii and T. turgidum var. durum could be used as gene sources for improving winter hardiness in hexaploid wheat.Key words: Freezing hardiness, Triticum tauschii, Triticum turgidum L. var. durum