Analyses of genetic diversity among maize inbred lines differing for resistance to pink borer and post-flowering stalk rot

Identification of the diverse sources of resistance is an important issue among the breeders for developing pest and disease free hybrids, to reduce the inoculum load, to prolong the life of inbred lines/hybrids and to reduce the cost of cultivation. Molecular diversity analysis was carried out among 23 maize inbred lines with respect to post flowering stalk rot and pink borer. Forty six SSR markers were employed among eight post flowering stalk rot (PFSR) and seven pink borer resistant lines along with eight other inbred lines to identify diverse resistant sources for developing resistant heterotic combinations to above pests and diseases. Number of alleles per SSR marker ranged from 2 to 9 averaging 4.11. The polymorphism information content (PIC) ranged from 0.272 to 0.839 with an average of 0.568. Discrimination rate (DR) of the markers ranged from 0.095 to 0.861 with a mean of 0.618. Number of alleles was highly correlated with PIC and DR. The pair-wise genetic dissimilarity values ranged from 0.05 to 0.84 with an overall mean of 0.64. Un-weighted neighbour joining clustering put 23 genotypes in two main clusters, which were further subdivided into 5 and 6 sub-clusters, respectively. We obtained 56 rare and 26 unique alleles in specific inbred lines, which can be used for identification of these lines. The present study has revealed considerable diversity among inbred lines differing for resistance against PFSR and pink borer; and provided ample scope for selection of parents for utilization in heterosis breeding