SOMATIC EMBRYOGENESIS AND PLANT-REGENERATION OF MAIZE TRIPSACUM HYBRIDS

Hybrids from five intergeneric crosses between maize and Tripsacum dac tyloides were evaluated for their ability to form long-term embryogeni c and regenerable callus cultures. Embryogenic cultures and plant rege neration were obtained from all five crosses tested. Maize inbred line s CML135 and Tzi18 that in a previous study were classified as non-emb ryogenic, originated embryogenic and regenerable calli from the immatu re hybrid embryos, suggesting that the embryogenic capacity may be imp roved by crossing recalcitrant maize genotypes with the wild relatives . The frequency of embryogenic callus ranged from 14.3 % to 66.6 % and Dicamba appeared to be more suitable than 2,4-D in stimulating embryo genic callus formation, although differences in morphology were not ob served between calli growing on medium supplemented with 2,4-D or Dica mba. The 97 regenerated hybrid plants rensembled the Tripsacum parent in vegetative morphology, they were male-sterile and tillered extensiv ely. Mitotic analysis showed that all regenerated plants had 46 chromo somes (10 Zm + 36 Td) and C-banding of these plane showed the absence of chromosome rearrangements and of large chromosome deficiencies.