Diversité phénotypique et moléculaire du blé dur cultivé en Algérie

Abstract

The genetic improvement of the agronomic traits related to the performance and adaptation to the environments is conditioned by the presence of a genetic and phenotypic variability of the targeted traits in the plant material subjected to the selection. In this work, three trials were conducted on the collection of 26 durum wheat (Triticum durum Desf.) from various origins. The first trial was realized during the campaign of 2011/2012 on the ITGC site of el khroub station in rainy conditions. This site represents the highest Algerian eastern plains. To assess the extent of phenotypic variability for future use. Various phenological and physiological parameters (The heading stage and maturity date, the temperature of crop canopy, relative water content), agronomics (The number of fertile tillers (NTF), the number of grass tillers (NTG), and (NTF/NTG). And quantitative morphological characteristics (plant height, flag leaf area, the length of beards, the spike length) and qualitative characteristics (spike and beards color and pubescence of glumes) were studied in the genotypes of durum wheat. The results obtained reveal highly significant varietal differences for all measured parameters. The second trial was conducted during the 2012/2013 campaign on the same site of previous experiments; in order to compare the production and performance of varieties studied under different climatic conditions. A significant effect years and varieties were revealed for the set of parameters, our results show that the end-of-cycle thermal stress induces a decrease of thousand kernel weight. Lack of water causes a decrease in the number of heads per m² and the number of grains per ear of all varieties. The Hoggar and Tassili varieties have good production capacity during the two trials compared to the other varieties. Highly positive significant links have been found between grain yield and the number of grains produced per unit area, and the number of grain per spike. The principal component analysis, described a total variation of 77.36 %, and the hierarchical classification has divided the genotypes according to their phenotypic variation into three distinct groups. The first one includes old varieties showing adaptability to climatic conditions to the studied area. They are late and large. In opposition to the two groups formed by varieties from (CIMMYT, ICARDA, and Italy) . They are characterized by a small, early maturity at heading, and show higher values for all performance components. The third trial was conducted in this study to evaluate the genetic diversity of durum wheat varieties using two types of molecular markers (SSR and RAPD). In total, 44 and 30 alleles were generated by 10 SSR primers and 05 RAPD primers respectively. The results obtained by the use of microsatellites, highlights variability within the 26 varieties. Reveal significant allelic diversity characterized by high polymorphic information content (PIC) values, highest are obtained by primers WMC 307 and BARC 142 with (0.85 and 0.73) respectively. And in agreement with the large number of polymorphic alleles detected in varieties with an average of 11.8 alleles.These results reinforces and justify the choice to use these primers association analysis in our durum wheat varieties. The classification of varieties according to UPGMA (Unweighted Pair Group Method with Arithmetic averaging) showed a wide genetic diversity, can be used in the choice of parents in the breeding program. Modern wheat varieties have diverged from Algerian and Italian durum wheat into two main distinct clusters. The results estimated by the RAPD markers also reveal a genetic polymorphism expressed by a PIC (0.31) and Shannon diversity index (0.410). AMOVA (Analysis of Molecular Variance) showed that genetic variation within groups represented 97% (ΦPT = 0.173 p <0.05).