Genetic and pathological diversity of the mango anthracnose pathogen in Florida.
Davis M. J.
Author Affiliation: Tropical Research and Education Center, University of Florida, 18905 SW 280 Street, Homestead, FL 33031, USA.
Proceedings of the Florida State Horticultural Society : 197-200
Abstract : Anthracnose, caused by Colletotrichum gloeosporioides [Glomerella cingulata], is considered the most important disease of mango (Mangifera indica) in the humid tropics. Randomly amplified polymorphic DNA (RAPD) analyses, pathogenicity tests on inflorescences and detached leaves and fruits (of cultivars Tommy Atkins and Kent), susceptibility to benomyl, and pectic zymogram analysis were used to examine diversity among 85 isolates of the pathogen collected from naturally infected leaves, peduncles, flowers, and immature, green and mature fruits in south Florida, USA. Although considerable genetic diversity was found, cluster analysis of the pathogenicity and RAPD data indicated several groups of isolates. Based on spore shape, one group might be classified as C. acutatum and not C. gloeosporioides. Isolates of the C. acutatum group tended to be slightly more virulent on inflorescences and less virulent on leaves and mature fruits. Such distinctions among Colletotrichum isolates from mango might be significant with respect to anthracnose control. All members of 2 of the 5 RAPD groups were resistant to benomyl, whereas benomyl resistance was not consistent for the other groups. The diversity of Colletotrichum associated with anthracnose of mango in Florida may help to explain why some mango cultivars with reported resistances to anthracnose elsewhere are susceptible in Florida.