Rapid induction by fungal elicitor of the synthesis of cinnamyl-alcohol dehydrogenase, a specific enzyme of lignin synthesis

Open Access
Publisher Website
Google Scholar
Abstract
A fivefold increase in the extractable activity of cinnamyl-alcohol dehydrogenase, an enzyme of phenylpropanoid metabolism specific for lignin synthesis, was observed within 10 h of treatment of cell-suspension cultures of bean (Phaseolus vulgaris L.) with a high-molecular-mass elicitor preparation heat-released from mycelial cell walls of the bean pathogen Colletotrichum lindemuthianum. Elicitor caused a rapid, marked but transient increase in the synthesis of cinnamyl-alcohol dehydrogenase with maximum rates 2–3 h after elicitation, concomitant with teh phase of rapid increase in enzyme activity. There is a close correspondence between increased polysomal mRNA activity encoding cinnamyl-alcohol dehydrogenase, as measured by incorporation of [35S]methionine into immunoprecipitable enzyme subunits in vitro, and the stimulation of enzyme synthesis in vivo in response to elicitor. This marked increase in polysomal mRNA activity represents an increase as a proportion of total cellular mRNA activity, indicating that elicitor does not stimulate synthesis of this enzyme by selective recruitment from the total pool of cellular mRNA. Elicitor stimulation of cinnamyl-alcohol dehydrogenase activity and enzyme synthesis is more rapid than previously observed for other proteins involved in inducible defense mechanisms, such as enzymes of phytoalexin biosynthesis or the apoproteins of cell-wall hydroxyprolinerich glycoproteins.