Sequence Characterized Amplified Regions Linked with Apomictic Mode of Reproduction in Four Different Apomictic <i>Cenchrus</i> Species

Abstract

The genus Cenchrus comprises tropical and sub-tropical forage grasses, many of which reproduce by aposporous apomixis. This mode of reproduction hampers genetic improvement of the species through conventional breeding; however, it may facilitate the fixing of heterosis in a hybrid. Apomixis can be deployed in plant breeding to maintain hybrid vigour over the generations, thereby accelerating the breeding process. Markers for apospory have been identified in grasses, but we have identified conserved genomic regions and apomixis-specific AFLP markers in eight Cenchrus spp. and converted them into sequence characterised amplified regions (SCARs). Seventeen of 94 identified polymorphic AFLP markers were located in the apospory-specific genomic region and were converted into SCAR markers. Only four (23.5%) were successfully converted into SCARs linked with an apomictic mode of reproduction in Cenchrus spp. The SCAR markers were validated in an F 2 population of C. ciliaris consisting of 48 apomictic and 38 sexual individuals. The SCARs were conserved across the four apomictic Cenchrus spp. with >98% sequence homology. In silico mapping of the SCARs based on sequence homology indicated synteny with segments of chromosome 12 of rice and chromosome 5 of maize. These markers would be very useful for genetic/molecular analyses of apomixis, comparative mapping studies and marker-assisted breeding of Cenchrus .