ABSTRACT
In the present study attempts have been made to characterize urease expression in slow growing Bradyrhizobium strains TAL442 and MO5 which are endosymbionts of green gram (Vigna radiata (L.)Wilczek). It was found that urease activity in vegetative cells of both the strains was inducible unlike their fast growing counterparts. Mode of regulation in TAL442 was governed by presence of ammonia. Urease expression was also detectable in bacteroids of both the strains which was not influenced by presence of external nickel chloride in high concentration, a situation detrimental to the vegetative cells.
ABSTRACT
Screening for resistant barley genotypes in response to fungal toxin of Bipolaris sorokiniana was assessed on standing barley plants as well as in selected callus lines of the same. For the standing lines tested, those manifesting chlorosis in response to toxin infiltration showed a significantly slower disease progress as compared to the necrotic lines. Also, necrosis in the callus tissues of the susceptible cultivar in MS medium supplemented with different concentrations of the crude toxin was significantly higher than in the callus tissues of the chlorotic lines studied. Similar host response to the toxin in in vitro and field situations open up the possibility of screening barley cultivars for resistance to spot blotch using callus culture as against classical methods of screening in order to increase accuracy and save time and space.