Progress in transformation and regeneration of tropical inbred maize lines in Kenya

Abstract

Tropical inbred maize lines have a reputation of being difficult to transform, mainly as a result of their inherent limitations associated with resistance to Agrobacterium infection and their recalcitrance to in vitro regeneration. To enhance the capacity for public sector maize transformation, the Plant Transformation Facility at Kenyatta University, Kenya, embarked on a program to improve transformation of diverse tropical inbred maize lines using Agrobacterium tumefaciens. We evaluated both N6 (Frame et al., Plant Physiol. 129:13-22, 2002) versus LS (Negrotto et al., Plant Cell Rep.19:798-803, 2000) media with different hormone regimes and optimized transformation and regeneration protocol for tropical inbred maize lines. Using immature embryos as explants, four Kenyan tropical inbred lines TL21, TL22, TL23 and TL18; two Sudanese inbred lines IL1, IL2 and CIMMYT inbred lines CML 216 and CML 244 have been investigated for their tenability to transformation and regeneration. Transformation frequencies (callus resistant events over total explants) and efficiencies (plantlet regenerating events over total explants) for the recovered events were used to evaluate successful transformation