Comparison Between Maize Inbred and Hybrid Lines for Their Amenability to Agrobacterium Mediated Transformation and In Vitro Plant Regeneration

The field of genetic engineering and molecular breeding utilizes maize immature embryos for transformation studies. However, there are hinderances such as the unavailability of immature embryos throughout the year and their low transformation frequencies which make them unsuitable for use at a commercial level. Among cereals, maize has prime importance due to its productivity, industrial products, animal feed and fodder. Regeneration capability in maize transformation studies varies due to differences in genetic makeup and explant source. In this study, we evaluate mature embryos as explants for in vitro plant regeneration. Six varieties including 3 hybrid lines (Pioneer 3025, SG 2002 and Neelam) and 3 inbred lines (NCML 107, CML 161 and FBF 3368) were screened for Agrobacterium mediated transformation amenability using mature maize embryos. The two inbred lines NCML 107 and CML 161 performed best showing 100% callus induction frequency, 93.33% and 86.66% transient GUS expression, and 43.75% and 13.3% regeneration frequency, respectively. Using split seed as an explant, better regeneration was observed in NCML 107 (14.86%) and CML 161 (7.5%) as compared to mature embryos, NCML 107 (10%) and CML 161 (2%). Here we report successful plant regeneration (regeneration medium supplemented with Kinetin + BAP) using split seeds as an explant. Our results demonstrate the capability of two elite maize inbred lines (NCML 107 & CML 161) for their amenability to Agrobacterium mediated transformation and better tissue culture response; hence can be selected in maize transformation studies for improving crop varieties for enhanced nutritional content and better adaptation.