Differential esterase expression in leaves of Manihot esculenta Crantz infected with Xanthomonas axonopodis pv. manihotis

The polyacrylamide gel electrophoresis system (PAGE) and inhibition tests f or biochemical characterization of alpha- and beta -esterases were used to obtain a functional classification of esterases in plants and to show a dif ferential expression of esterases as markers of pathogenesis in cassava pla nts (Manihot esculenta Crantz). The characterization of alpha- and beta -es terases from leaves of M. esculenta by the PAGE system was possible using a n extraction solution containing two phenol-complexing agents (PVP-40 and s odium metabisulfite), three antioxidant agents (EDTA, beta -mercaptoethanol , and DTT), and one quinone reducer (ascorbic acid). Fourteen esterase isoz ymes were detected in young unexpanded leaves of M. esculenta cultivars. Th e inhibition pattern of alpha- and beta -esterases of M. esculenta showed t hat Est-9 is an arylesterase, and in the unexpended leaves of the M. escule nta plants infected with Xanthomonas axonopodis pu manihotis, the Est-7 bet a -esterase showed the characteristic staining of an alpha/beta -esterase. This differential expression of Est-7 isozyme in young unexpanded leaves of cassava plants can be used as a marker of pathogenesis after infection wit h X. axonopodis pu manihotis.