ENZYMATIC ACTIVITY OF PATHOGENESIS-RELATED (PR) PROTEINS OF FIVE LOCAL BANANA CULTIVARS DURING RIPENING

Abstract

The biochemical activity of five pathogenesis-related (PR) proteins were determined in the peel and pulp of five local banana cultivars, namely ‘Berangan’ (AAA), ‘Mas’ (AA), ‘Abu’ (AAB), ‘Rajah’ (ABB) and ‘Rastali’ (AAB) at four ripening stages, Stages I, III, V and VII. Results showed that peroxidase decreased at later stages of ripening in both the peel and pulp of the fruit. Peroxidase and polyphenol oxidase were observed to be higher in the peel than in the pulp. Conversely, both the I±-amylase activity and the trypsin inhibitory activity were observed to be higher in the pulp as compared to the peel of the fruit. Trypsin inhibitory activity was also observed to be significantly higher in the later stages of ripening. The laminarinase assay showed a decrease in activity for all cultivars except the ‘Abu’ cultivar.