Molecular and Agro-physiological Approaches for Parental Selection before Intercrossing in Salt Tolerance Breeding Programs of Durum Wheat

摘要

A set of six Tunisian durum wheat varieties (Triticum turgidum L. subsp. durum Desf.) were used for developing and validating an approach to select parental genotypes before intercrossing them for salt tolerance breeding programs. This research was designed to study both molecular genetic diversity and differences in patterns of agro-physiological responses to salt stress. Different agro-physiological measurements were conducted for both the saline treatment (10 g/1 NaCl) and the control. The data were converted to salt tolerance indices to allow comparisons among genotypes for salt sensibility. Genetic diversity among these varieties was determined by comparing their molecular traits. A dendrogram of genetic similarity was established using 46 polymorphic markers from eight SSRs and four RAPD primers. The results revealed that the most affected agro-physiological parameters were tiller number, chlorophyll content at 110 and 120 days, shoot dry weight, number of spikes/plant and total grain yield.For these parameters the most affected genotypes were 'Karim' and 'Nasr' and the least affected were 'Maali' and 'Razzek'. The dendrogram discriminated 'Karim' from the remaining analysed varieties. Except for 'Karim', the remaining varieties were tightly clustered in the dendrogram, which reflects a narrow genetic base and low genetic variability among those genotypes. The genetic diversity of Tunisian durum wheat varieties could be enlarged by combining desired traits from different local and wild populations of different geographical origins into the breeding lines. Finally, we conclude that both molecular and agro-physiological approaches are helpful for current and future breeding programs in order to select genetically distinct parents with different salt tolerance components.