Molecular characterization of the chromosome segment governing apospory in Paspalum notatum (Bahiagrass)

PESSINO SC; STEIN J; PODIO M; RODRIGUEZ MP; LASPINA NV; FELITTI, S; MARTÍNEZ EJ; SIENA LA; QUARIN CL; ORTIZ JPA

San Diego, CA, USA

Congreso; Plant and Animal Genome XVI Conference; 2008

The International Conference on the status of Plant and Animal Genome Research

Paspalun notatum Flugge is a warm-season forage grass with sexual diploid and apomictic tetraploid races. Natural populations are widely distributed in the New Word from Mexico to Argentina and throughout the West Indies. The objective of this work was to characterize the genomic region responsible for apospory in the species. A mapping population segregating for apospory was used to develop a full genetic map. The apo-locus was identified as a single non-recombinant genomic region of around 36 Mbp, presenting preferential pairing to one of the homologues. Nine DNA fragments mapping within this region were isolated and sequenced. Several of them corresponded to repetitive elements, with others displayed homology with functional genes or intergenic regions. Mthylation sensitive genome hybridization blots revealed cytosine methylation at the region. Comparative mapping using RFLP probes showed that the apo-region is syntenic to particular segments of rice chromosome 2 and 12 and it is probably inverted in the apomictic race. Moreover, cytogenetic evidence of a possible genomic inversion affecting the apomictic genotypes was obtained from chromosome paring analysis at meiosis. At least two probes derived from genes silenced in apomictic plants mapped linked to the apo region. Our results suggest that apospory in P. notatum is controlled by a complex non-recombinant locus, probably originated from an inversion, including abundant repetitive elements, displaying cytosine methylation and possible silenced,