Assignment of a gene(s) conferring apomixis in Tripsacum to a chromosome arm: cytological and molecular evidence

Attempts are underway to locate and transfer genes conferring diplosporous apomixis from Tripsacum to maize. The objective of this study was to evaluate several apomictic and sexual maize-Tripsacum hybrids for the presence or absence of Tripsacum chromosomes, PCR-RAPD generated markers, and RFLP markers that would have an association with apomictic development. Cytological and molecular analysis resulted in the identification of the Tripsacum chromosome arm carrying the gene(s) conferring diplosporous apomixis. Evaluations made on apomictic sexually derived maize + Tripsacum addition lines and an apomictic line possessing a Mz6L-Tr16L translocation were used to establish the location of the gene(s). Results of the study indicate that the successful transfer of a single Tripsacum chromosome is all that is necessary to maintain apomictic reproduction in a maize background. Additional use of this material may facilitate the development of an apomictic maize prototype and the eventual isolation of the gene(s).