Differential Esterase Expression in Leaves of Manihot esculenta Crantz Infected with Xanthomonas axonopodis pv. manihotis

The polyacrylamide gel electrophoresis system (PAGE) and inhibition tests for biochemical characterization of alpha- and beta-esterases were used to obtain a functional classification of esterases in plants and to show a differential expression of esterases as markers of pathogenesis in cassava plants (Manihot esculenta Crantz). The characterization of alpha- and beta-esterases from leaves of M. esculenta by the PAGE system was possible using an extraction solution containing two phenol-complexing agents (PVP-40 and sodium metabisulfite), three antioxidant agents (EDTA, beta-mercaptoethanol, and DTT), and one quinone reducer (ascorbic acid). Fourteen esterase isozymes were detected in young unexpanded leaves of M. esculenta cultivars. The inhibition pattern of alpha- and beta-esterases of M. esculenta showed that Est-9 is an arylesterase, and in the unexpanded leaves of the M. esculenta plants infected with Xanthomonas axonopodis pv. manihotis, the Est-7 beta-esterase showed the characteristic staining of an alpha/beta-esterase. This diffrential expression of Est-7 isozyme in young unexpanded leaves of cassava plants can be used as a marker of pathogenesis after infection with X. axonopodis pv. manihotis.