Diversity of Colletotrichum causing anthracnose on Psidium guajava in varied Brazilian physiographic regions

Abstract

Anthracnose, caused by several Colletotrichum species, is a major restricting factor for guava production, but no comprehensive study of the causal agent has been conducted from the plant host centre of diversity. This work characterizes isolates from guava, mainly from the fruit, but also leaves and flowers, representing most Brazilian physiographies according to the partial sequences of the rDNA-ITS, ApMAT, TUB2, HIS3 and GAPDH gene regions. In addition, the pathogenicity and aggressiveness to fruits of two widely planted guava varieties (SLG and RM) are described. Guava-derived Colletotrichum isolates were found in five complexes: gloeosporioides, acutatum, boninense, gigasporum and orchidearum. The gloeosporioides complex was the most prevalent (81%), followed by the acutatum complex (14%). A total of 16 Colletotrichum species were naturally associated with guava anthracnose: C. aeschynomenes, C. asianum, C. chrysophilum, C. fructicola, C. gigasporum, C. gloeosporioides, C. karsti, C. melonis, C. musae, C. nymphaeae, C. paranaense, C. siamense, C. sojae, C. syzygicola, C. theobromicola and C. tropicale. Apart from C. nymphaeae and C. gloeosporioides, all the remaining 14 taxa are reported for the first time in P. guajava. The most aggressive species belonged to the C. gloeosporioides complex. C. siamense was the most prevalent, especially in warmer regions, followed by C. chrysophilum, mostly in temperate environments. The most aggressive species were C. siamense, C. chrysophilum, C. fructicola and C. tropicale. Fruits of the variety SLG were consistently more resistant to anthracnose than the fruits of RM.