Some Cytomorphological Evidence for Synthesis of Interspecific Hybrids between Brassica juncea and Autotetraploid B. fruticulosa

Four successful interspecific hybrid plants were obtained through sexual hybridization between Brassica juncea cv. Rohini, Laxmi, and Varuna (2n=4x=36, AABB), and an autotetraploid B. fruticulosa (2n=4x=32, FFFF) induced by colchicine using the latter as a pollen parent. Morphological and cytological analyses were carried out to confirm the hybrid nature of F-1 plants. The F-1 plants (2n=34) were intermediate for most of the morphological attributes. Although, the F(1)s showed poor pollen fertility, nevertheless, few seeds were obtained from open pollination. Meiotic analysis of F-1 plants showed a predominance of univalents, a typical feature of hybrids. The occurrence of bivalents, trivalent, and quadrivalent in PMCs of the F(1)s indicated homeologous pairing among the three genomes. The study suggests that B. fruticulosa has partial genome homeology with B. juncea which could be exploited in crop improvement programmes, particularly breeding for biotic stress especially, tolerance/resistance to the mustard aphid.