Bulk Segregant Analysis (BSA) for the improvement of Drought Resistance in Maize (Zea mays L.) Inbred Lines as revealed by SSR Molecular Markers

In this study, maize inbred lines were used to evaluate performance under drought stress. Based on germination ability, 24 lines were screened out with tolerance or susceptibility to drought stress. Genetic diversity, relationship and population structure were evaluated by using 100 SSR molecular markers linked with drought tolerance in maize. A total of 465 alleles were identified with an average of 4.65 alleles per locus using bulk segregant analysis (BSA). Out of them, 199 were specific alleles with tolerance and 35 were susceptible to drought while the remaining 231 were shared between the two types. The major allele frequency varied from 0.39 to 0.61 with an average of 0.47. The gene diversity (GD) and polymorphic information content (PIC) average values from all lines were 0.64 and 0.59 respectively. Based on UPGMA analysis, four main cluster groups were identified as most of the drought tolerant lines were clearly discriminated from drought susceptible lines with 33% genetic similarity. On population structure analysis, 24 inbred lines with tolerance and susceptibility were divided into 3 groups. In addition to BSA, a total of 88 SSR's were identified as specific to tolerance and 29 SSR markers were specific to susceptible lines. Among these, bnlg1627, umc1946, dupssr30b, bnlg1812 and dupssr24 SSR markers had great potential for the improvement of drought resistance in maize. Our results were in good agreement with previous studies for drought tolerance using SSR molecular marker and will be useful for further maize breeding studies.