Molecular markers associated with salt tolerance in Egyptian wheats
Salinity affects plant growth by the osmotic stress of the salt around the roots, as well as by toxicity caused by excessive accumulation of salt in leaves. In the present study, seven common (Triticum aestivum) and two durum (T. turgidum ssp. Durum) wheat genotypes were subjected to salt stress for 2 weeks. Salt stress decreased leaf osmotic potential in all cultivars. The difference in osmotic adjustment between the cultivars was correlated with the concentrations of minerals examined such as Na+ and K+. The salt tolerance in the T. aestivum cultivar Gemmiza 10 and in T. durum cultivars Sohag and Beni Sweif was due to higher ability to maintain osmotic potential of the cells than the other cultivars by increase in osmoticum concentration under salt stress. The genetic variation and relationships among different wheat genotypes with different responses to salt stress were also investigated by RAPD and SSR analyses. 82 out of 118 RAPD markers detected were polymorphic (69.5%) and 42 out of 59 SSR alleles were polymorphic (71%), and can be considered as useful markers for the wheat cultivars tested. 18 random amplified polymorphic DNAs (RAPD) markers and 13 simple sequence repeats (SSR) markers generated were found to be genotype-specific. Seven markers distinguished the cultivar Beni Sweif, six markers for the cultivar Sohag and two markers for the cultivar Gemmiza 10. These markers can be verified as being genetic markers associated with salt tolerance in the three wheat genotypes and help in marker-assisted selection breeding program.
Key words: Osmotic adjustment, RAPD and SSR marker, salt tolerance, wheat genomes.