Plant, Animal & Microbe Genomes X Conference Plant, Animal & Microbe Genomes X ConferenceJanuary 12-16, 2002
Town & Country Convention Center
San Diego, CA
Workshop: Apomixis
Paspalum simplex is a grass species that exists as apomictic tetraploid (2n=4x=40) races that are sexually compatible with their obligate sexual diploid counterparts. Taking advantage of the synteny recently demonstrated between many grasses and rice, rice probes of known map position were used as anchor markers to screen a population of P.simplex segregating for apomixis. Of the 112 markers screened, evenly distributed along the rice chromosomes, 5 showed tight linkage with apomixis without any recombination event detected among the 87 individuals of the mapping population. These apomixis-linked markers spun 15 cM on the telomeric part of the long arm of rice chromosome 12 but were inherited as a single genetic unit in P.simplex indicating strong repression of recombination in the apomixis-controlling locus (ACL). If the ACL has been isolated by the lack of recombination, then hemizygosity (i.e. uniqueness of sequence) due to sequence divergence should be expected. Such hemizygosity is unlikely evidenced with heterologous markers belonging to a sexual species. Therefore seventy-four primer/enzyme combinations were screened for AFLP analysis of the mapping population yielding other 5 markers tightly linked to apomixis. When these markers were converted RFLPs one of them proved to belong to a hemizygous region of the ACL. If apomixis in P.simplex shows a so strong synteny with rice then candidate genes should emerge from the rice database.