Development of Cajanus platycarpus x Cajanus cajan hybrids through embryo rescue

Abstract

Crosses were made between pigeonpea [Cajanus eajan (L.) Millsp.) and its wild relative C. platyearpus to diversify the existing gene pool for the traits like earliness, photo-insensitivity etc. through introgression of genes from the later. Hybridization was attempted between C. platyearpus x C. eajan genotypes Pant A-3, UPAS-120, BR-183, BR-65, ICP-6344, Bahar, BS-7-14-3, BS-7-8-2, Pusa-9 and ICP 7119. Since, the pollen of C. platyearpus failed to germinate on the stigma of C. eajan, the former was only used as the female parent. The crosses were only successful in case of C. eajan genotype Bahar, UP AS-120, Pant A-3 and BR-65. The hybrid pod did not develop properly and the ovule development was also poor. In order to rescue the hybrid embryo, it was cultured at different stages of development on MS medium supplemented with various concentrations and combinations of phytohormones. The best medium to rescue the hybrids through embryo culture was MS+NAA (0.5 mgtl) + BAP (0.5 mg/l). Only the hybrids C. platyearpus x C. eajan var. Bahar and A. platyearpus var. Pant A-3 could survive through embryo culture. These hybrids were properly rooted and transferred to the pots for their confirmation of hybridity and further evaluation. Isozyme of peroxidase was used to confirm the hybridity.