SEPARATION FROM USTILAGO SCITAMINEA OF DIFFERENT ELICITORS WHICH MODIFY THE PATTERN OF PHENOLIC ACCUMULATION IN SUGARCANE LEAVES

Abstract

Smut caused by Ustilago scitaminea (Syd.) is a major disease of sugarcane. Different compounds from a crude fungal extract were separated by capillary electrophoresis. These compounds produced changes in the accumulation of free phenolics and enhanced phenylalanine ammonia-lyase and peroxidase activities in sugarcane leaves of the susceptible cv. Mayari 5514, and the resistant cv. Barbados 42231. Smut-elicitor fractions were resolved by capillary electrophoresis as different peaks. Those inducing the highest biological activity were resolved as three main peaks corresponding to negatively charged proteins, peptides or glycopeptides of medium molecular mass. These compounds enhanced the accumulation of free phenolics, mainly hydroxycinamic acids, by activation of phenylalanine ammonia- lyase in the resistant cultivar, and hydroxybenzoic acids in the susceptible cultivar. Another important difference was the enhancement in the resistant cultivar of peroxidase, an enzyme that uses free phenolics as substrates for the activation of important mechanisms of resistance of sugarcane leaves to the fungal pathogen.