Assessment of Relationship for Both Seedling and Maturity Traits with SSR Markers under Drought Conditions in Bread Wheat (Triticum asetivum L.)

Twenty-one cultivars of bread wheat were evaluated for drought-stress tolerance at seedling ‎and maturity stages under non-drought and drought-stress conditions. Significant differences among ‎genotypes were obtained under non-drought and drought-stress conditions for all seedling and ‎maturity characteristics. Highly positive and significant correlations were found for root length with ‎respect to fresh weight of 0.74 and dry weight seedling of 0.80. However, negative and highly ‎significant correlations were found for both drought susceptible index based on seedling traits ‎‎(DSIST) and maturity traits (DSIST) with all seedling traits except root: shoot ratio, whereas no ‎correlations were obtained for either DSIST or DSIMT with all maturity traits except 1000 kernel ‎weight. Positive and highly significant correlation found between DSIST and DSIMT (0.85). SSR ‎markers analysis showed that three bands produced by Xgwm596-7A (507 bp), Xgwm497-1A (556 ‎bp) and Xgwm174-5D (409 bp), they were presented in all tolerant genotypes based on DSIST. The ‎three bands (507, 556 and 409 bp) were correlated to DSIST, with R2 values of 81.05%, whereas the ‎three bands were correlated to DSIMT with R2 values of 61.96%. Strong association was observed for ‎genotypic distance with phenotypic distance based on seedling characteristics, that amounted to ‎‎0.66, whereas the correlation was less strong between genotypic distance and phenotypic distance ‎based on maturity traits by 0.30. The seedling traits at 15% PEG were more association than maturity ‎traits under drought-stress with SSR markers, this gives preference to using seedling traits as an ‎indicator of drought-stress tolerance in breeding programs.‎