MOLECULAR VARIATIONS OF MAIZE CMS POPULATIONS AND SUBPOPULATIONS

Abstract

RAPD DNA markers were used to evaluate trends in genetic diversity among 20 of 24 cms line populations derived from early and advanced cycles of selection. All of the 10 RAPD primers used for initial screening were found to be polymorphic. A total of 139 DNA fragments were generated by 10 random decamer primers, with an average of 13.9 easily scorable fragments per primer. The number of amplified fragments produced per primer ranged from 6 for OPC-02 primer to 21 for OPC-07 and OPE-07 primers, with molecular size ranged from 264bp to 2717bp. The total number of polymorphic fragments and the percentage of polymorphism were 109 and 78%, respectively. Maximum level of polymorphisms were (94%) and (93%) observed for the primers OPD-05 and OPC-08, respectively. Primers OPC-02 and OPD-08 showed the lowest percentage of polymorphism, which were about (50%) and (53%), respectively. Based on the bivariate (1-0) data and genetic similarity with the use of UPGMA cluster method, the dendrogram separated the studied populations into five major clusters I, II, III, IV and V. Cluster analysis which compared between original and subpopulations places in the dendrogram, showed that selection plays an important role in developing new populations via selfing. R6O and its progeny R6S showed a diverged genetic background against other populations. Genetic similarities, computed by Nei and Li’s similarity coefficient revealed that the highest estimate (0.97) was observed between the original and subpopulation of R6. Meanwhile the lowest genetic similarity (0.76) was detected between the original and subpopulation of R2. The highest genetic similarity among the different populations was 0.89 observed between R3O and both R4 populations, whereas genetic distance widened slightly in R6 population after three cycles of selection as R6s possessed the lowest GS value (0.57) against A5O. Relationship between genetic diversity and hybrid vigor was fair enough. Results indicated that DNA molecular markers were highly efficient in detecting the purity and genetic relationship among maize cms populations.