Molecular cytogenetics of the apomixis controlling locus in Paspalum simplex

Apomictic plants give rise to seeds that are genetically identical to the mother plant. To characterize cytologically the locus controlling the apomictic reproduction of Paspalum simplex, FISH analysis of meiotic chromosomes was performed using an apomixis-linked BAC clone as a probe. The locus was embedded in a heterochromatin-poor region not adjacent to the centromere. Sequence analysis of the probe used confirmed the strong synteny between the apomixis locus of P. simplex and the telomere of the long arm of chromosome 12 of rice. Nevertheless, both large- and small-scale rearrangements of the region compared to the related area of rice were revealed. Results are discussed in relation to the use of rice genomic data for positional cloning of apomixis genes and to the possible role of gene rearrangements in the apomictic development of P. simplex.