Response of interspecific Brassica juncea/Brassica rapa hybrids and their advanced progenies to Albugo candida (white blister)

Transfer of factors for resistance to white blister disease caused by Albugo candida between Brassica species involving two genotypes each of B. juncea and B. rapa was studied in hybrids. More hybrids were obtained by in vivo than in vitro techniques, although an in vitro phase was a prerequisite for the establishment of in vivo hybrids. Hybrids were identified by PCR-based inter-simple sequence repeat (ISSR) markers with both male and female species-specific bands being identified. There was a positive correlation between disease severity and number of days after sowing (r > 0.93), the highest being towards pod formation and plant maturity at 110 days after sowing. The plants from F-2 and BC1 progeny showed higher resistance to A. candida than either of the parents. Plants of B. juncea and B. rapa with high field resistance (disease index < 1.0) were selected from BC2 and F2BC1 generations. The frequency of plants classified as resistant in BC2 progeny ranged from 4.5 to 39.0% in cross-combinations involving B. juncea genotypes as female parent, compared with 100% in the reciprocal cross involving B. rapa as female parent.