Cuticular Wax of Tectona grandis L. Leaves – A Resistance Marker against Plant Pathogens

Abstract

The leaf surface of higher plants is composed of varied profile of hydrocarbons which play a vital role in chemical recognition and potentially involved in plant-pathogen interactions and communication with nature. There is little evidence to the direction that plant cuticle play a major factor in plant defense against pathogens besides imparting physical barrier to the plant. Teak (Tectona grandis. L) is one such tree found with diverse geographical distribution. In the present work, our objective was to study the cuticular composition of the fresh leaves of teak which is responsible for its wide adaptation and its antimicrobial activity. Cuticular compounds from the hexane fraction of the teak leaves were isolated, purified and spectral analyses revealed a long chain unbranched heneicosane (C21) with a mol. wt. of 296. This saturated hydrocarbon forms a continuous layer on the leaf surfaces which act as physical barrier to the micro-organisms and also possesses a strong defensing activity against a number of pathogens which implies its role in defensive mechanisms of the plant. The antifungal activity of heneicosane on each of the microbial species was statistically significant at P≤0.001 level. Its abundant recovery from teak leaves may justify its putative role as a resistance marker.