Submitted to: Genome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/1996
Publication Date: N/A
Interpretive Summary: In maize, the absolute method of producing seed is through sexual means. Sexuality provides for genetic segregation from one generation to the next. An apomictic type of reproduction would however prevent genetic segregation and stabilize the genetics of a particular line indefinitely. There are and have been several attempts to transfer the genes controlling apomixis (asexual reproduction by seed) to maize from its most distant relative Tripsacum. However, to date, none have been successful. If the genes controlling apomixis can be successfully transferred to maize, it could reduce the cost of producing hybrid maize and provide dramatic cost reduction to the farmer/grower since the hybrids would indefinitely maintain their level of hybrid vigor and production potential. The present research identifies the location of the genes controlling the trait to a specific chromosome arm of the Tripsacum genetic complement. In addition, that particular Tripsacum chromosome arm has been translocated to a maize chromosome providing the stable maintenance of the Tripsacum segment via a maize centromere. Cytological, molecular and progeny tests were used to identify and verify that the specific Tripsacum segment carries the genes controlling apomictic reproduction. These materials will provide the foundation for the development of an apomictic maize prototype. This research is of particular interest to cytogeneticists, geneticists and maize breeders interested in transferring apomixis to additional maize lines.
Technical Abstract: 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 PCR-RAPD generated markers which would have an association to apomictic development. Cytological and molecular analysis utilizing these markers 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 carrying 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 eventual isolation of the gene(s).