Study of fertilization barriers in crosses between Sesamum indicum and its wild relatives

Crosses were made using the cultivated species S. indicum cv. DS-1 and cv. E-8 as the male parents and the wild species S. occidentale, S. radiatum and S. mulayanum as the female parents. Studies on field pollination and in vivo pollen germination, the barriers to hybridization were classified as post-zygotic, in the crosses S. occidentale x DS-1, S. occidentale x E-8, S. radiatum x DS-1 and S. radiatum x E-8. Seeds observed were shrivelled and failed to germinate. Embryo abortion at the later stages may be the major cause for hybrid inviability. In the crosses with S. mulayanum as the female parent, viable F1's were obtained indicating absence of fertilization barriers. The possible roles of the enzymes, esterases and peroxidases in cross-compatibility were studied but none was found to affect inter-specific compatibility.