Transcriptional analysis of Camellia oleifera inoculated with Colletotrichum fructicola from Different Geographic regions

Anthracnose, caused by Colletotrichum. Spp., is an important disease affecting oil tea (Camellia oleifera), where infection can cause reductions in yield and oil quality. In recent years, extensive molecular studies have demonstrated that Colletotrichum fructicola is the dominant pathogen of oil tea anthracnose in China. To investigate differences in molecular processes and regulatory genes at different stages of infection of C. fructicola, we compared the pathogenicity of C. fructicola from different populations (Wuzhishan, Hainan province and Shaoyang, Hunan province), and gene expression of representative strains of the two populations before and after infection with Camellia oleifera using RNA sequencing. We found that C. fructicola from Wuzhishan has a stronger ability to infect and impact oil tea leaf tissue. Up-regulated genes in oil tea following infection with the two geographic populations were associated with a number of ribosome-related GO and KEGG pathways, and were significantly enriched in galactosidase activity, glutamine family amino acid metabolism, arginine and proline metabolism. These results indicate that C. fructicola obtained sugars and amino acids from oil tea tissue to resist host immune pressure. Up-regulated gene lists associated with infection by the Wuzhishan strains were significantly enriched in ribosome-related metabolic pathways as well as purine metabolism pathways, while Shaoyang strains were not significantly enriched in these processes. Differences in gene expression were indicative of greater active transcription and translation in oil tea infected with the Wuzhishan population while more active glycoprotein metabolism was observed following inoculation with strains from Shaoyang. The greater regulation of purine metabolism pathway in oil tea inoculated with the Wuzhishan strain might contribute to its stronger pathogenicity. The results of this study will aide in understanding differences in pathogenic mechanisms of C. fructicola of different geographic populations.