Role of phosphorylase and amylase in accelerated ripening of mutant banana ‘Basrai-10Gy’

Abstract

‘Basrai-10Gy’, a mutant developed by <img src='/image/spc_char/gamma2.gif'>- irradiation of shoot-cultures of the ‘Basrai’ banana, ripened much faster compared to its parent. The biochemical mechanism underlying the faster ripening of the mutant was investigated. Ripening was assessed by determining textural changes in the whole fruit, the peel and the pulp, as well as from the physical changes of ripening. The activities of amylase (E.C.3.2.1.3) and starch phosphorylase (E.C. 2.4.1.21), the enzymes that initiate the catabolism of starch, were comparatively evaluated in the parent and mutant variety. They were correlated with the ripening behaviour of the fruit. An increase in the amylase activity, associated with the climacteric and normal ripening behaviour, was observed in ‘Basrai’ bananas; while, the phosphorylase activity was comparatively insignificant. The mutant variety showed low amylase and very high phosphorylase activities, suggesting the direct availability of sugar phosphate instead of free sugars to accelerate the ripening of ‘Basrai-10Gy’ fruit.