Identification and Characterization of <i>Colletotrichum</i> Species Associated with Maize in Sichuan, China

<i>Colletotrichum</i> species are the most common cause of maize anthracnose, which often manifests as leaf spots. However, field observations often reveal symptoms similar to those caused by other leaf spot pathogens, such as <i>Curvularia</i> and <i>Bipolaris</i>. In this study, 99 isolates were identified using tissue separation and single-spore isolation techniques. As preliminary measures of species diversity, all 99 isolates were identified morphologically, and the glyceraldehyde-3-phosphate dehydrogenase (<i>GAPDH</i>) gene sequences were phylogenetically analyzed. Furthermore, 48 representative strains were selected for molecular identification using multi-locus phylogenetic analyses based on five gene loci (ITS, <i>TUB</i>, <i>ACT</i>, <i>GAPDH</i>, and <i>CAL</i>). Finally, 10 species of <i>Colletotrichum</i> isolated from maize leaf spots were identified. <i>Colletotrichum cliviicola</i> was the most dominant species (24.2%), followed by <i>C. fructicola</i> (18.2%), <i>C. karstii</i> (16.1%), <i>C. siamense</i> (13.1%), <i>C. boninense</i> (7.1%), <i>C. kahawae</i> (7.1%), <i>C. brevisporum</i> (6.1%), <i>C. truncatum</i> (5.1%), <i>C. gigasporum</i> (2.0%), and <i>C. gloeosporioides</i> (1.0%). For the first time, pathogenicity tests revealed that <i>C. cliviicola</i>, <i>C. fructicola</i>, <i>C. siamense</i>, <i>C. karstii</i>, and <i>C. truncatum</i> are the causative agents of maize anthracnose. Additionally, <i>C. boninense</i> was identified as an endophytic fungus on healthy maize. In conclusion, this study is the first to identify the pathogen of maize anthracnose in Sichuan Province. It provides valuable insights for accurately diagnosing and managing maize anthracnose.