Abstract

                                Electrophoretic study was conducted to find out the isozymic differences of ribo- nucleases (RNases) between bacterial leaf blight (BLB) resistant and susceptible varie- ties of rice. Three susceptible varieties: T(N) 1, Jamuna and Varuna and three resistant varieties; IR 20, IR 22 and UPRI 71-12 were used in the investigation. Maximum of eight bands (isozymes) of RNase I and five bands of RNase I were observed at the various stages of development. The activity of RNase I decreased whereas RNase II activity increased from zero-hour to 96-hour stages of germination. The activity of RNase I was higher in the susceptible variaties than the resistant varie- ties while RNase II activity was higher in the resistant varieties throughout the differ- ent stages of germination. The specific bands 7 and 8 of RNase were associated with BLB susceptiblity. The band 5 of RNase II was specific to resistant varieties.

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