Pectinolytic activity of 40 isolates of Colletotrichum gloeosporioides obtained from Stylosanthes spp.lesions, in distinct producing regions, was estimated through the enzymatic diffusion in pectin-medium free of glucose, and measured by pectin degradation. All isolates showed pectinolytic activity, and were divided in five groups. Moderate production of pectic enzymes was evidenced in the majority of the isolates. In general, isolates from Camapua-MS presented low genetic diversity for the production of pectinases. Taking into account the activity of pectinases, isolates of the pathogen were selected and inoculated in S. capitata (GC1081, GC1084, GC1086 and GC1094), S. scabra (GC1496) and S. macrocephala (GC1511). Thus, the enzyme influence on aggressiveness to the host was evaluated. Initially, aggressiveness test was installed with the isolates CG656, CG657, CG687, CG706 and CG707. Differences in aggressiveness were observed only when the isolates were inoculated in S. scabra. The isolates CG657, CG706 and CG707 were the most aggressive, and CG656 was the least aggressive. Another aggressiveness test was established to evaluate the isolates CG768, CG769, CG772, CG775, CG779 and CG781. These isolates showed differences in their aggressiveness when inoculated in S. capitata (GC1081 and GC1094) and S. macrocephala (GC1511). In general, CG768 exhibited the lowest while, CG772, CG775 and CG781 the highest aggressiveness. In both aggressiveness tests, there were no evidences for a direct correlation of anthracnose increase in severity with the of the pectinolytic activity. For the conditions evaluated, the pectic enzymes did not influence the aggressiveness of C. gloeosporioides to the stylo.
Pectinases; cell wall degrading enzymes; Glomerella cingulata; anthracnose; pathogenic variability; stylo
