ROLE OF PEROXIDASE AND ESTERASE ISOENZYMES IN PEA ROOTS INFECTED WITH HETERODERA GOETTINGIANA

M. T. Melillo, T. Bleve-Zacheo, G. Zacheo

Abstract


A cytochemical and biochemical study of peroxidase and esterase activity of pea roots susceptible or resistant to Heterodera goettingiana has shown that the levels of activity of the two enzymes appeared to be related to infection and differed with regard to pea resistance. Infected tissues of resistant roots showed a marked increase in peroxidase activity, which became perceptible within 24h of infection and continued for several days; cycloheximide treatment prevented this induction. The high level of peroxidase is to be considered part of a general activation of the cell metabolism, which takes the form of de novo synthesis of enzymatic proteins with peroxidase activity. The peroxidases and carboxylesterases localized near the infected tissues appear to catalyze the formation of suberin. The activity of these enzymes seems to precede the suberization of cell walls. Presumably, the deposition of suberin aids in the defense of the plant by forming a barrier that blocks the pathogen. We therefore propose a correlation of the two enzymes as a rapid and sensitive response in the incompatible pea-cyst nematode interaction.

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