An apospory-specific genomic region is conserved between Buffelgrass (Cenchrus ciliaris L.) and Pennisetum squamulatum Fresen

Twelve molecular markers linked to pseudogamous a form of gametophytic apom ixis, were previously isolated from Pennisetum squamulatum Fresen. No recom bination between these markers was found in a segregating population of 397 individuals (Ozias-Akins et al., 1998, Proc. Natl Acad. Sci. USA, 95, 5127 -5132). The objective of the present study was to test if these markers wer e also linked to the aposporous mode of reproduction in two small segregati ng populations of Cenchrus ciliaris (= Pennisetum ciliare (L.)Link), anothe r apomictic grass species. Among 12 markers (sequence characterized amplifi ed regions, SCARs), six were scored as dominant markers between aposporous and sexual C. ciliaris genotypes (presence/absence, respectively). Five wer e always linked to apospory and one showed a low level of recombination in 84 progenies. Restriction fragment length polymorphisms (RFLPs) were observ ed between sexual and apomictic phenotypes for three of the six remaining S CARs from P. squamulatum when used as probes. No recombination was observed in the F-1 progenies. Preliminary data from megabase DNA analysis and sequ encing in both species indicate that an apospory specific genomic region (A SGR) is highly conserved between the two species. Although C. ciliaris has a smaller genome size to P squamulatum, a higher copy number for markers li nked to apospory found in the former may impair the progress of positional cloning of gene(s) for apomixis in this species.