Identification and Characterization of<i>Colletotrichum</i>Species Associated with Anthracnose Disease of<i>Camellia oleifera</i>in China

Abstract

Tea-oil tree (<i>Camellia oleifera</i> Abel) is an important edible oil woody plant with a planting area over 3,800,000 hectares in southern China. Anthracnose is a serious disease of tea-oil tree in southern China, causing severe economic losses and posing a huge threat to the <i>Ca. oleifera</i> industry. Based on recent developments in the classification of <i>Colletotrichum</i> species, the objective of this study was to identify <i>Colletotrichum</i> species associated with tea-oil tree and examine their pathogenicity on leaves and fruits of <i>Ca. oleifera</i>. In total, 232 isolates were obtained from <i>Ca. oleifera</i> leaves and fruits with anthracnose symptoms. These isolates were further characterized based on morphology and multilocus phylogenetic analyses using partial DNA sequences at the ribosomal internal transcribed spacer regions and β-tubulin, actin, calmodulin, glyceraldehyde-3-phosphate dehydrogenase, and chitin synthase-encoding genes. The fungal isolates belong to five species: <i>C</i>. <i>camelliae</i>, <i>C. fructicola</i>, <i>C. siamense</i>, <i>C. aenigma</i>, and <i>C. gloeosporioides</i>. <i>C</i>. <i>camelliae</i> was the most predominant and widely distributed species on fruits of <i>Ca. oleifera</i> (91.4%), followed by <i>C. fructicola</i> (6.3%). However, <i>C</i>. <i>fructicola</i> was common and widely distributed species on leaves (75.9%), followed by <i>C</i>. <i>camelliae</i> (17.2%). There was no evidence of geographical specialization of the different species. Pathogenicity assays showed that all tested isolates, including 20 of <i>C</i>. <i>camelliae</i>, 11 of <i>C. fructicola</i>, four of <i>C. siamense</i>, two of <i>C. aenigma</i>, and one of <i>C</i>. <i>gloeosporioides</i>, were pathogenic to leaves and fruits of <i>Ca. oleifera</i>. Among the five species, <i>C</i>. <i>camelliae</i> species showed strong pathogenicity on both leaves and fruits of <i>Ca. oleifera</i>, and <i>C. fructicola</i>, <i>C. siamense</i>, <i>C. aenigma</i>, and <i>C. gloeosporioides</i> all showed weak pathogenicity on both leaves and fruits. No relationship was found between origin of isolates and their virulence. This is the first description of <i>C</i>. <i>camelliae</i>, <i>C. fructicola</i>, <i>C. siamense</i>, and <i>C. gloeosporioides</i> from the fruits of <i>Ca. oleifera</i> in China.