Ammonia-lyase and O-methyl transferase activities related to lignification in wheat leaves infected with botrytis

Abstract

The deposition of lignin around wounds in wheat leaves infected with the non-pathogenic fungus Botrytis cinerea, was preceded by increases in ammonia-lyase and O-methyl transferase activities. The increases were localised in the lignifying tissues. Phenylalanine ammonia-lyase and tyrosine ammonia-lyase increased concurrently and were inseparable by gel filtration or DEAE cellulose chromatography, the two activities probably being the function of a single protein. Infection-specific isoenzymes for either of the ammonia-lyase activities were absent. Increases in caffeic acid O-methyl transferase and 5-hydroxyferulic acid O-methyl transferase activities closely followed those of the ammonia- lyases. It is unlikely that the increased proportion of syringyl groups found in infection-induced lignin is controlled by O-methyl transferase activity. A modified method for the estimation of O-methyl transferase activity in crude wheat extracts is described.