A Portion of the Apomixis Locus of Paspalum Simplex is Microsyntenic with an Unstable Chromosome Segment Highly Conserved Among Poaceae

Abstract

The introgression of apomixis in major seed crops, would guarantee self-seeding of superior heterotic seeds over generations. In the grass species Paspalum simplex, apomixis is controlled by a single locus in which recombination is blocked. In the perspective of isolating the genetic determinants of apomixis, we report data on sequencing, in silico mapping and expression analysis of some of the genes contained in two cloned genomic regions of the apomixis locus of P. simplex. In silico mapping allowed us to identify a conserved synteny group homoeologous to the apomixis locus, located on a telomeric position of chromosomes 12, 8, 3 and 4 of rice, Sorghum bicolor, Setaria italica and Brachypodium distachyum, respectively, and on a more centromeric position of maize chromosome 1. Selected genes of the apomixis locus expressed sense and antisense transcripts in reproductively committed cells of sexual and apomictic ovules. Some of the genes considered here expressed apomixis-specifc allelic variants which showed partial non-overlapping expression patterns with alleles shared by sexual and apomictic reproductive phenotypes. Our fndings open new routes for the isolation of the genetic determinants of apomixis and, in perspective, for its introgression in crop grasses.