Genetic Mapping in Sugarcane: Prospects and Progress in the South African Sugar Industry

Genetic mapping of a South African sugarcane cross, the AA40 population, was initiated with the ultimate aim of being able to identify genetic markers linked to important traits. This population is derived from a routine cross in the SASEX plant breeding programme, and was selected for mapping purposes due to the good segregation observed for various traits, for example resistance to diseases such as smut and rust. Initial molecular analysis of the progeny revealed that the identity of the male parent was not as originally supposed. Attempts were made to identify the true male parent, but these were unsuccessful. The inability to identify the male parent, however, is not crucial to the mapping project but merely limits the rate of accumulation of mapping data. Eighty AA40 progeny are being used for the generation of the map, whereby single-dose restriction fragment length markers are identified and used for linkage analysis. Although the linkage data generated to date are very much in the preliminary stages, the routine identification of singledose markers will ultimately result in the definition of specific linkage groups. Phenotypic data of various traits can then be mapped, allowing the localisation of important genes in the sugarcane genome.