Caracterização morfológica, atividade enzimática e processo inicial de colonização de Colletotrichum guaranicola patogênico e endofítico

Abstract

Paullinia cupana (guarana) is a tropical plant originated from the forest of the Brazilian Amazon. However, guarana production has been declining in the state of Amazonas, in comparison with the production of the State of Bahia. The main limiting factor of production and expansion in the state of Amazonas is anthracnose, caused by Colletotrichum guaranicola, which is considered the most serious disease of guarana culture. This study aimed to characterize the isolates of C. guaranicola pathogenic and endophytic, from guarana, considering cultural, morphological, molecular, enzymatic and histological aspects, in order to determine differences between pathogenic and endophytic. In the present work, 9 endophytic and 14 pathogenic isolated from C. guaranicola were obtained through indirect isolation of healthy leaves and guarana anthracnose symptoms. The isolates were characterized by morphological and cultural characteristics. The molecular identification involved PCR analysis using primers GACA4, GTG5 and M13. The enzyme activity, the following enzymes were tested: lipase, amylase, protease, polyphenoloxidase, cellulase and pectinase. The pathogenicity test was conducted in order to select one isolated pathogenic and one isolated endophytic for analysis of the pre-penetration process and colonization of the pathogen in the tissues of susceptible leaves (clone 300) of guarana. About the Morphocultura characterization, pathogenic and endophytic isolates presented great variability. The color of the colony and size of conidia differed between endophytes and pathogens. It was not possible to make a correlation with Morphocultural and molecular analysis with pathogenic and endophytic isolates. Genotyping confirmed that all isolates belong to the genus Colletotrichum, however, it was not possible to identify the isolated species level to the genre. There was no difference between the enzyme and endophytic pathogens, it is not possible to find correspondence with the infection process in guarana leaves. The period of 48 hours after inoculation allowed to verify 100% germination and appressorium formation in the isolated pathogenic, in addition to colonization in tissues of the plant, by contrast to the endophyte which showed lower percentages for germination and formation of appressoria, and it was not observed colonizing tissues 48 hours after inoculation.