Discovery of the Gene Influencing Fruit Forms of Oil Palm

The oil palm (Elaeis guineensis) has three fruit forms, namely dura (thick shelled), tenera (thin shelled) and pisifera (shell-less). Tenera is a hybrid between the other two fruit forms and yields up to 30% more oil than dura, while pisifera, the source of pollen, is usually female sterile.  The monogenic, co-dominant inheritance of shell was first discovered  in the 1940s in Zaire, Africa and the tenera fruit form has been the commercial planting material in South East Asia since the 1960s. Using a combination of genetic mapping, homozygosity mapping by sequencing and the oil palm whole genome sequence as a reference, the homologue of the MADS box gene SEEDTICK was found to be responsible for the three different fruit forms of  E. guineensis. Analyzing breeding lines and germplasm collection from Africa revealed two independent mutations in the gene, explaining the heterosis observed in tenera palms. The identification of the gene responsible for the fruit forms paves the way for application of molecular diagnostic tools in both oil palm breeding and commercial seed production.