Wide Hybridization in Sorghum: Studies on Crossability Barriers in the Cross S. bicolor x S, dimidiatum Using Excised Spikelets

摘要

Sorghum [Sorghum bicolor (L.) Moench] cultivars are susceptible to a range of biotic and abiotic stresses because of the narrow genetic base of an elite gene pool. Many of the wild species are repositories of genes imparting resistance/tolerance to these stresses (Dahlberg and Spinks 1995, Prasada Rao et al. 1989). Wide hybridization using a sexual, or a somatic pathway is therefore an important technique for sorghum improvement. However, most of the wild species show strong crossability barriers with the cultivated species. An understanding of the nature of such barriers would be very useful to the development of effective techniques to circumvent the barriers. Sorghum dimidiatum possesses many useful genes including those that confer resistance to shoot fly and drought. Making hybrids with this species through conventional hybridization is extremely difficult (Prasada Rao et al. 1991). We studied the details of crossability barriers for this combination using excised spikelets.