Abstract

Field grown, self pollinated maize genotypes were planted in KARI (Kiboko andKabete) research stations between January 2004 and May 2005. Immaturemaize embryos from twelve parental inbred lines and their respective single cross hybrids were evaluated for their ability form callus, somatic embryos and subsequent regeneration into plants. The embryos were excised from surface sterilized kernels harvested at different physiological stages, namely 10 - 24 days after pollination (DAP). They were used as explants to initiate callus on solid N6 basal media with varying level of 2,4-D (0 - 20 mg L^-1) and regenerated on hormone free MS media. Optimal induction of primary callus at 2 mg L^-1 averaged 83% and 67 in hybrids and inbred lines respectively. Somatic embryo competence was demonstrated in 6 inbreeds and 4 hybrids. However, plant regeneration was only achieved in 4 inbreeds and 3 hybrids. 90% percent of regenerants were normal and fertile. The successful regeneration of some of the inbred lines and/or hybrids provides a basis for development of genetic transformation using Agrobacterium tumefaciens to improve priority traits such as enhanced insects/pest and drought tolerance.

Key words: Inbred lines and hybrids, immature embryos, in vitro plant regeneration, recalcitrancy.

Abbreviation

TH, hybrid; TL, inbredline; DAP, days after pollination; 2,4-D dichlorophenoacetic acid.