Host-induced silencing of theColletotrichum gloeosporioides conidial morphology 1gene (CgCOM1) confers resistance against Anthracnose disease in chilli and tomato

Key message Host mediated silencing ofCOM1gene ofColletotrichum gloeosporioidesdisables appressorial differentiation and effectively prevents the development of Anthracnose disease in chilli and tomato. Anthracnose disease is caused by the ascomycetes fungal speciesColletotrichum, which is responsible for heavy yield losses in chilli and tomato worldwide. Conventionally, harmful pesticides are used to contain anthracnose disease with limited success. In this study, we assessed the potential of Host-Induced Gene Silencing (HIGS) approach to target the Colletotrichum gloeosporioides COM1(CgCOM1) developmental gene involved in the fungal conidial and appressorium formation, to restrict fungal infection in chilli and tomato fruits. For this study, we have developed stable transgenic lines of chilli and tomato expressingCgCOM1-RNAi construct employingAgrobacterium-mediated transformation. Transgenic plants were characterized by molecular and gene expression analyses. Production of specificCgCOM1siRNA in transgenic chilli and tomato RNAi lines was confirmed by stem-loop RT-PCR. Fungal challenge assays on leaves and fruits showed that the transgenic lines were resistant to anthracnose disease-causingC. gloeosporioidesin comparison to wild type and empty-vector control plants. RT-qPCR analyses in transgenic lines revealed extremely low abundance ofCgCOM1transcripts in the C.gloeosporioidesinfected tissues, indicating near complete silencing ofCgCOM1gene expression in the pathogen. Microscopic examination of theCg-challenged leaves of chilli-CgCOM1i lines revealed highly suppressed conidial germination, germ tube development, appressoria formation and mycelial growth ofC. gloeosporioides, resulting in reduced infection of plant tissues. These results demonstrated highly efficient use of HIGS in silencing the expression of essential fungal developmental genes to inhibit the growth of pathogenic fungi, thus providing a highly precise approach to arrest the spread of disease.