Fenóis, peroxidase e polifenoloxidase na resistencia do cafeeiro a Meloidogyne incognita

Seedlings of two coffee cultivars were inoculated with the nematode Meloidogyne incognita: cv. Mundo Novo (susceptible) of Coffea arabica and cv. Apoata (resistant) of C. canephora. During the larval penetration and adult female phases of the parasite, evaluations were made on phenol content, peroxidase and polyphenoloxidase activities. In the two evaluations, no differences were observed in roots and shoots growth among inoculated and non inoculated seedling. For both cultivars, only in the first phase infected seedlings showed an increase in phenols as compared to their counterparts not inoculated. However, phenol values were higher in the second than in the first phase. The cv. Mundo Novo had always higher phenols content than Apoata. Only inoculated seedlings of the cv. Mundo Novo showed an increase of peroxidase activities in the first phase; but, both cultivars presented higher peroxidase activities in the second phase as compared to the first. Apoata seedlings has always higher peroxidase and polyphenoloxidase activities than Mundo Novo. Infected seedlings of the cv. Apoata showed in the first phase, only, an increase in polyphenoloxidase activity. Thin-layer chromatograms of phenolic extracts did not present any difference among inoculated and non-inoculated seedlings. Twenty three spots on the chromatograms were common to both cultivars, except than Apoata had a further nine spots not found in Mundo Novo and the later had a further eleven not found in the former