Distribution and Pathogenicity of <i>Colletotrichum</i> Species Associated With Mango Anthracnose in Mexico

Abstract

Mango anthracnose, caused by <i>Colletotrichum</i> spp., is the most significant disease of mango (<i>Mangifera indica</i> L.) in almost all production areas around the world. In Mexico, mango anthracnose has only been attributed to <i>C. asianum</i> and <i>C. gloeosporioides</i>. The aims of this study were to identify the <i>Colletotrichum</i> species associated with mango anthracnose symptoms in Mexico by phylogenetic inference using the <i>ApMat</i> marker, to determine the distribution of these species, and to test their pathogenicity and virulence on mango fruits. Surveys were carried out from 2010 to 2012 in 59 commercial orchards in the major mango growing states of Mexico, and a total of 118 isolates were obtained from leaves, twigs, and fruits with typical anthracnose symptoms. All isolates were tentatively identified in the <i>C. gloeosporioides</i> species complex based on morphological and cultural characteristics. The Bayesian inference phylogenetic tree generated with <i>Apn2</i>/MAT intergenic spacer sequences of 59 isolates (one per orchard) revealed that <i>C. alienum</i>, <i>C. asianum</i>, <i>C. fructicola</i>, <i>C. siamense</i>, and <i>C. tropicale</i> were associated with symptoms of mango anthracnose. In this study, <i>C. alienum</i>, <i>C. fructicola</i>, <i>C. siamense</i>, and <i>C. tropicale</i> are reported for the first time in association with mango tissues in Mexico. This study represents the first report of <i>C. alienum</i> causing mango anthracnose worldwide. The distribution of <i>Colletotrichum</i> species varied among the mango growing states from Mexico. Chiapas was the only state in which all five species were found. Pathogenicity tests on mango fruit cultivar Manila showed that all <i>Colletotrichum</i> species from this study could induce anthracnose lesions. However, differences in virulence were evident among species. <i>C. siamense</i> and <i>C. asianum</i> were the most virulent, whereas <i>C. alienum</i> and <i>C. fructicola</i> were considered the least virulent species.