Abstract:
Maize is one of the most important cereal crops in Sub-Saharan Africa and an important source of energy for humans.
However, the difference in the dedifferentiation frequency of immature embryos among various genotypes indicates that callus
induction and genetic transformation is dependent on the genotype. This phenomenon is an impediment in the fundamental process
of improving tropical maize germplasm especially through genetic engineering. Here, five tropical maize (Zea mays L.) genotypes,
CML 216, CML 144, A 04, E 04 and TL 21, were evaluated for callus induction on MS medium supplemented with the growth
regulator dicamba. Embryogenic and non embryogenic callus induction was independent of genotype when young immature embryos,
12 days after pollination (DAP) were used for tissue culture in combination with dicamba. The optimal concentration of dicamba for
induction of embryogenic callus in all the genotypes was 3 mg/L, which was also the concentration at which non embryogenic callus
formation was lowest. The frequency of embryogenic callus induction ranged from 35% to 79% among the five genotypes and
somatic embryos regenerated R0 shoots that produced normal R1 progenies. This regeneration method is expected to facilitate the
development of a more efficient genotype independent Agrobacterium- mediated transformation system for tropical inbred lines.
