Expression of resistance to Karnal bunt (Neovossia indica) in embryo cultures of wheat

Joint culturing of Neovossia indica and embryos of resistant (HD 29 and WH 283) and susceptible (HD 2009, HD 2329 and WH 147) wheat genotypes was done on modified MS medium. Growth of N. indica did not affect the callusing frequency of the embryos but embryos formed a circular inhibition zone around themselves in which pathogen growth was absent. The diameter of this zone was little more in resistant genotypes and varied from 2.42 cm in WH 283 to 2.76 em in HD 29. In susceptible lines it ranged from 1.74 to 2.12 cm. The ability to form this inhibition zone was lost when just initiated callus or 15 days old callus was cultured in presence of the pathogen. The callus growth was not affected by the pathogen except in initial stage.