Identification of pathogenic-like fungal species on Akebia trifoliata fruit by integrating transcriptome analysis and specific sequences of putative pathogens

Large-scale cultivation of recently domesticated crops poses great potential disease risk, so rapid and comprehensive identification of pathogenic microbes is of great significance and value for the commercial development of wild plant resources. Akebia trifoliata is widely cultivated in various regions of China, although its domestication remains in the early stages. Here, to avoid large economic losses, we identified the pathogenic-like fungi of widely cultivated A. trifoliata based on causal relationship between pathogens and hosts such as discernible symptoms, fungal diversity and differentially expressed sequences in symptomatic and asymptomatic fruits. First, we observed partly discernible symptoms of four diseases (powdery mildew, anthracnose, fruit shrinkage and brown spot) by observing disease development in the field. Second, comparative analysis of the ITS sequences between the symptomatic and asymptomatic rind bulks suggested that Cercospora , Colletotrichum and Strelitziana could contain pathogenic-like fungi. Finally, interaction transcriptome sequencing afforded strong evidence for 20 pathogenic-like fungi associated with five reported diseases in A. trifoliata and other plants and seven putative unknown diseases, among which the pathogenic-like fungi causing anthracnose, powdery mildew and brown spot were the three top richness fungi in symptomatic fruit rind. This study provides a new strategy for the rapid identification of pathogenic-like fungi in plants and provides some reference for farmers to prevent and control A. trifoliata diseases.