Regenerability of elite tropical maize ( Zea mays L.) inbred lines using immature zygotic embryo explants

Five elite tropical maize inbred lines; CML395, CML443, CML442, MAS [MSR/312]-117-2-2-1-B-5-B) and CML216 as a control, were evaluated for their regenerability making use of calli derived from immature zygotic embryos. Murashige and Skoog basal salts supplemented with 1.0, 1.5, 2.0 and 2.5 mg/L 2,4dichlorophenoxyacetic acid were used to induce callus. Callus induction frequency and formation of embryogenic callus varied significantly (p<0.01) depending on genotype and level of 2,4dichlorophenoxyacetic acid. Shoot regeneration efficiency also differed significantly (p<0.01) depending on genotype. Significantly (p<0.05) higher callus induction and frequency of embryogenic callus were obtained at 1 mg/L 2,4-dichlorophenoxyacetic acid, indicating this as the optimal level for regenerating these inbred lines. CML395 and CML442 revealed significantly (p<0.05) higher callus induction and embryogenic callus frequency compared to CML443 and MAS [MSR/312]-117-2-2-1-B-5B), while they were at par with the control inbred line CML216. Plants were regenerated from all the inbred lines except CML443 and were successfully acclimatized and grown to maturity. CML395 was the best regenerable line with significantly (p<0.05) higher regeneration efficiency of 109.3%. It was concluded that CML395, CML216 and CML442 can be used in in vitro genetic transformation.