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Sichuan Agricultural University (2007)

Evaluation of Triticum Durum L. Germplasms and Its Utilization in Wheat Improvement


Titre : Evaluation of Triticum Durum L. Germplasms and Its Utilization in Wheat Improvement

Auteur : 王含彦

Grade : Doctoral Dissertation 2007

Université : Sichuan Agricultural University

Résumé partiel
It is well known that the genetic diversity of cultivated wheat has been greatly eroded by modem breeding and planting modes. Narrow genetic basic not only limits the further improvement of yield and quality but also makes wheat increasingly vulnerable to biological and environmental stress. Therefore it is necessary to find and utilize the beneficial gene resource from the relative of cultivated wheat. Triticum durum L., with many useful genes for wheat improvement, is the secondary gene pool of bread wheat and easy to be utilized by hybridizing. Thus, it is important to evaluate the germplasm of durum wheat. In this paper, the population genetic diversity was estimated based on agronomic traits, SDS-/A-PAGE and EST-SSRs markers. In addition, threeα-gliadin genes from durum wheat were isolated and characterized. Furthermore, the durum wheat accession with high protein content was hybridized with cultivated wheat variety, and the cytological and agronomic characteristics of the F2 and F3 population were analyzed. The main results were described as following:1. The eight agronomic traits and grain protein content of 101 Triticum durum L. collected from eight countries and areas, were investigated based on analysis of variance, correlation, principal component and cluster. Higher variations of the eight agronomic traits were observed. The durum wheat investigated in this study have the beneficial traits of more tillers and spikelet per spike, and disadvantage of higher plant height, lower 1000-grain weight and longer growing periods. By clustering analysis, all the materials were divided into four groups, indicating that genetic distances based on agronomic traits were not associated with their geographic distribution. According to these main characters, tweenty-two accessions with one or some elite agronomic performances were screen out.2. The diversity of the storage proteins of 142 durum wheat accessions from 22 countries and areas was characterized by A-PAGE and SDS-PAGE. The higher gliadin genetic variation was observed by A-PAGE in the durum wheat. Furthermore, 142 accessions were divided into three major groups using the clustering analysis, indicating that the gliadin variations among durum wheat were associated with their geographic origin. A total of 14 HMW glutenin subunits alleles and 15 subunits combinations in T. durum L. studied. Tweenty accessions with subunits combinations being positive for quality were identified, which could be utilized in common wheat quality improvement. Meanwhile, two accessions were found to containing null subunits on Glu-A1 and Glu-B1, which was useful to characterize that how other endosperm protein than HMW-glutenin subunits effect the wheat quality.3. Using wheat EST-SSR markers, 60 durum wheat (Triticum durum L.) accessions from seven countries were investigated. Twenty-five primer pairs could amplify successfully in the 60 durum wheat accessions, of which tri-nucleotides repeats was dominant type. Higher numbers of alleles and PIC were identified on B genome than those on A genome. Mantel-test showed the genetic similarity coefficient matrix obtained from A genome markers was significant linear relative to that from B genome (P<0.001), which suggested that the genetic differentiation among accessions reflected by two genomes was resemblant. Both Shannon’s index and Gst (genotype/accession differentiation) indicated that the most significant differentiation had occurred in the durum wheat accessions from China.

Mots clés : Triticum durum L.; genetic evaluation; agronomic traits; storage protein; EST-SSR; hybridization improvement;

Présentation (CNKI)

Page publiée le 26 avril 2018