GROWTH AND SPORULATION OF COLLETOTRICHUM ACUTATUM AND C. GLOEOSPORIOIDES AND BIOCHEMICAL CHANGES DUE TO INFECTION IN HEVEA BRASILIENSIS

摘要

The Colletotrichum leaf disease caused by Colletotrichum acutatum and C. gloeosporioides is an important disease during the immature phase of rubber (Hevea brasiliensis). The aggressiveness of the pathogen varies between the species and therefore a study was undertaken to understand the physiological requirement of both the species and the biochemical changes consequent to infection. Both species preferred fructose as carbon source and aspargine as nitrogen source. They also responded similarly to pH and temperature levels, with pH 6.0 to 7.5 and temperature 25 ℃ being optimum for growth and sporulation. The changes in the activity of peroxidase, phenylalanine ammonia lyase and total protein content were studied by inoculating the two species of Colletotrichum on the leaves of clones RRII105 and RRIM 600. Significantly higher activities of peroxidase and phenylalanine ammonia lyase were noticed in the clone RRIM 600 inoculated with C. acutatum at 24 and 48 h after induction, respectively. Steady increase in total protein content was also observed up to 72 h in this clone when inoculated with C. acutatum. The tolerance in the clone RRIM 600 to Colletotrichum is attributed to this higher enzyme activity.