Diversidade de espécies de Colletotrichum endofíticos em cajueiros

Abstract

Native to South America, the cashew tree (Anacardium occidentale L.) is one of the most important cultivated fruit species in tropical regions. In Brazil, production is concentrated in the Northeast region, representing 99.5% of the cultivated area in the country. However, in recent years productivity has been decreasing due to several factors, the most important of which is the incidence of diseases. Anthracnose is the main cashew disease occurring throughout the country and caused by several species of the genus Colletotrichum. Previous studies have investigated the symptomatic species associated with cashew trees, but the diversity of endophytic species has not yet been studied. In view of this, the present study aimed to evaluate the diversity of endophytic species of Colletotrichum in the cashew tree in the state of Pernambuco, to identify these species through phylogenetic analyses, to evaluate the prevalence of Colletotrichum species in different organs of the cashew tree and, finally, to evaluate the pathogenicity and aggressiveness in cashew leaves. A total of 37 isolates were recovered from two non-commercial plantation areas, 12 isolated from area I (UFRPE) and 25 isolated from area II (UFPE). Different inoculation methods were tested. Six species of Colletotrichum (C. asianum, C. chrysophilum, C. karsti, C. siamense, C. theobromicola, C. tropicale) were identified as endophytes of cashew trees. Colletotrichum tropicale was the prevalent species in all areas and in all plant tissues collected. Mature tissues were the organs most colonized by endophytic species of Colletotrichum. All Colletotrichum species were pathogenic to wounded cashew leaves, however the methods without wounding did not show significant lesions. As for aggressiveness, C. siamense was the most aggressive species compared to other species.