Plant & Animal Genome IX Conference Plant & Animal Genome IX Conference
Workshop: Apomixis
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Apomixis, an asexual mode of reproduction through seeds, represents a promising tool for plant breeding and agriculture as it allows the fixation of any allelic combination. Tripsacum, a wild relative of maize, is a unique source of apomixis, as it can be readily crossed with maize. Moreover, because of colinearity of the grass genomes, some of the wide knowledge accumulated in maize reproductive biology and genetics can be applied to the study of apomixis in Tripsacum. Our objective is to identify the functional components of apomixis in Tripsacum to introduce them into diploid maize. Two different approaches of our effort will be described. (1) We have introduced transposable elements of the Mutator family into apomictic maize/Tripsacum hybrids. Transposon activity in the absence of meiosis has been demonstrated. This approach should permit the dissection of the apomictic process in spite of the restriction to recombination characterizing the genomic segment carrying apomixis. Preliminary results of our transposon tagging scheme will be presented. (2) Comparative mapping has shown colinearity between the maize and Tripsacum genomes. Consequently, a basic set of genes should be shared in these two grasses. If correct, the genes responsible for apomixis, but not the alleles, would also be present in maize. Numerous mutants in sexual reproduction have been described in maize. Based on their map location and on their similarity to apomixis, a few interesting candidates have been selected. An overview of these candidates will be presented in conjunction with an update on their isolation.