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Twenty four SSR primer pairs were used to determine the genetic diversity in the subspecies of Aegilops tauschii . All microsatellite markers showed a high level of polymorphism. The average number of alleles observed was relatively similar in subsp. tauschii (9.00) to that in strangulata (8.30). The tauschii group had also similar average PIC value (0.80) with the strangulata group (0.77). The range of similarity was higher in subsp. tauschii than subsp. strangulata , reflecting a higher level of genetic variation in the first subspecies. Cluster and PCO analyses revealed a relative pattern of differentiation between two taxonomic classified subspecies, but there were some exceptional accessions in each group, reflecting possible intermediate forms between these two subspecies. Wide distribution of alleles found in both subspecies can be used for wheat improvement.

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Simple sequence repeat (SSR) DNA markers were used to characterize the genetic diversity in 70 accessions of Aegilops crassa from Iran as well as to determine relationships among these accessions with 9 accessions of Aegilops tauschii (subsp. tauschii and strangulata ) and 5 Triticum aestivum landraces. All twenty SSR primer pairs were polymorphic and identified a total number of 149 alleles corresponding to an average of 7.5 alleles per locus. The highest and lowest PIC values were obtained in subsp. strangulata and Ae. crassa accessions, respectively. Data obtained were used to estimate genetic similarity using the Dice coefficient, and dendrogram was constructed using the UPGMA method. The dendrogram separated the 84 accessions into two main groups. All species grouped according to their genomes. A good level of genetic diversity was observed in the accessions of Ae. crassa , even in geographically close regions, which can be used in the broadening of the genetic base of bread wheat. In addition, T. aestivum and subsp. tauschii were clustered further away from Ae. crassa , confirming probably chromosomal rearrangements in the Dgenome of Ae. crassa during the processes of evolution.

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Cereal Research Communications
Authors: S.M. Pirseyedi, A. Kumar, F. Ghavami, J.B. Hegstad, M. Mergoum, M. Mazaheri, S.F. Kianian, and E.M. Elias

Fusarium head blight (FHB) damage in durum wheat (Triticum turgidum L. var. durum Desf., turgidum) inflicted massive economic losses worldwide. Meanwhile, FHB resistant durum wheat germplasm is extremely limited. ‘Tunisian108’ is a newly identified tetraploid wheat with FHB resistance. However, genomic regions in ‘Tunisian108’ that significantly associated with FHB resistance are yet unclear. Therefore, a population of 171 backcross inbred lines (BC1F7) derived from a cross between ‘Tunisian108’ and a susceptible durum cultivar ‘Ben’ was characterized. Fusarium graminearum (R010, R1267, and R1322) was point inoculated (greenhouse) or spawn inoculated (field) in 2010 and 2011. Disease severity, Fusarium-damaged kernel (FDK) and mycotoxins were measured. Analysis of variance showed significant genotype and genotype by environment effect on all traits. Approximately 8% of the lines in field and 25% of the lines in greenhouse were more resistance than Tunisian108. A framework linkage map of 267 DArt plus 62 SSR markers was developed representing 239 unique loci and covering a total distance of 1887.6 cM. Composite interval mapping revealed nine QTL for FHB severity, four QTL for DON, and four QTL for FDK on seven chromosomes. Two novel QTL, Qfhb.ndsu-3BL and Qfhb.ndsu-2B, were identified for disease severity, explaining 11 and 6% of the phenotypic variation, respectively. Also, a QTL with large effect on severity and a QTL with negative effect on FDK on chromosome 5A were identified. Importantly, a novel region on chromosome 2B was identified with multiple FHB resistance. Validation on these QTL would facilitate the durum wheat resistance breeding.

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