Efficient plant regeneration from shoot apex explants of maize (Zea mays) and analysis of genetic fidelity of regenerated plants by ISSR markers

An efficacious regeneration system was developed from shoot apex explants of Zea mays using a two-step culture procedure. Seventeen Indian genotypes were assessed for their regeneration potential. The maximum response of shoot induction was obtained from explants cultured on Murashige and Skoog medium supplemented with 4.5 µM thidiazuron and 26.7 µM glycine. Maximum mean number of shoots (17.2) was observed in genotype COH (m)-5 while NPK was the least responsive (6.7). Shoot clumps transferred from shoot induction medium to multiplication (second) medium amended with 1.1 µM thidiazuron and 0.88 µM N ₆ -benzylaminopurine showed increased number of shoots in COH (m)-5 (36.1 shoots); NPK was the least responsive with an average of 9.5 shoots. The best response in root induction, with a larger number of roots (10.5) and longer roots (6.6 cm), was observed in Murashige and Skoog medium supplemented with 7.3 µM indole-3-butyric acid and 7.9 µM phloroglucinol. Analysis of variance indicated that plant regeneration response varied greatly among the genotypes. In vitro raised plants were successfully transferred to the field after hardening, with a 99 % survival rate. Inter simple sequence repeats analysis revealed that the similarity matrix pair-wise value was 1, the Mantel test value was p 1.0; Analysis of molecular variance genetic variances were 93 % within the population and 7 % between populations; Principal component jolliffe cut off was 0.15, Principal component and Principle coordinate analysis % variance was 13.19. These values were congruent for both the mother and the in vitro-raised plants, confirming genetic integrity.