Transcriptomics and metabolomics reveal the induction of flavonoid biosynthesis pathway in the interaction of Stylosanthes-Colletotrichum gloeosporioides.

Colletotrichum, a hemibiotrophic fungal pathogen with a broad host range, causes a yield-limiting disease called anthracnose. Stylo (Stylosanthes) is a dominant pasture legume in tropics and subtropics, and anthracnose is one of its most destructive disease. Resistance mechanisms against anthracnose in stylo are poorly understood, thus hindering the development of resistant varieties. We performed time-resolved leaf transcriptomics, metabolomics and in vitro inhibition assay to investigate the defense responses against Colletotrichum gloeosporioides in stylo. Transcriptomics demonstrated that flavonoid biosynthetic genes were significantly induced during the infection. Consistently, metabolomics also showed the increased accumulation of flavonoid compounds. In vitro assays showed that phloretin and naringenin inhibited the mycelial growth, and apigenin, daidzein, quercetin and kaempferol suppressed conidial germination of Colletotrichum strains. Together, our results suggest that stylo plants cope with C. gloeosporioides by up-regulation of genes and compounds in flavonoid biosynthesis pathway, providing potential targets for resistance breeding.