Development of Alternaria blight resistant lines through interspecific hybridization between Indian mustard (Brassica juncea L.) and white mustard (Brassica alba) through embryo rescue

Abstract

Wide hybridization is an important technique for incorporation of desirable characters among related species of plants.
In the present study, interspecific hybridization was carried out through in vitro culture of ovules from the crosses
between Brassica juncea (cv. RH30, RH8812, RH270 and RH345) and B. alba for purpose of transferring Alternaria blight
resistance from B. alba to B. juncea. Ovules were excised from siliquae and cultured on seven different MS modified
media. In all crosses, the hybrid siliquae were shorter in length than their parent plants due to interspecific hybridization
barriers. Pod setting in hybrid plants ranged from 39 to 48% and number of ovules per pod were also very few. Best
germination response was observed in ovules used from 20 DAP on basal medium supplemented with Kin (2.5 mg/l) and
CH (0.5 g/l) (for cv. RH30 x B. alba) and MS + BAP (2.5 mg/l) + CH (0.5 mg/l) (for other crosses). Six rooting media were
tried for root formation in regenerated shoots. Maximum rooting response was on MS medium supplemented with IAA
(0.5 mg/l) in all hybrids. The regenerated hybrid plants were transferred to a mixture of sand: soil in 1:1 ratio in pots and
about 70 percent hybrid plants for all the crosses were survived. Successful hybrid plants were grown in field upto F7
generations. Advanced generation progenies were also successfully confirmed using molecular marker analyses for
Alternaria blight resistance character. In advanced generation, the hybrid plant’s characteristics were comparable to
their Indian mustard parent plants and they were highly resistant to Alternaria blight disease.