SilencingAC1of Tomato leaf curl virus using artificial microRNA confers resistance to leaf curl disease in transgenic tomato

Key message Expression of artificial microRNA targeting ATP binding domain of AC1 in transgenic tomato confers resistance to Tomato leaf curl disease without impacting the yield of tomato. Tomato curl leaf disease caused byTomato leaf curl virus(ToLCV) is a key constraint to tomato cultivation worldwide. Engineering transgenic plants expressing artificial microRNAs (amiRNAs) against the AC1 gene ofTomato leaf curl New Delhi virus(ToLCNDV), which is important for virus replication and pathogenicity, would consequently confer virus resistance and reduce crop loss in the economically important crops. This study relates to an amiRNA developed on the sequence ofArabidopsismiRNA319a, targeting the ATP/GTP binding domain ofAC1gene of ToLCNDV. The AC1-amiR was found to regulate the abundance ofAC1, providing an excellent strategy in providing defense against ToLCNDV. Transgenic lines over-expressing AC1-amiR, when challenged with ToLCNDV, showed reduced disease symptoms and high percentage resistance ranging between similar to 40 and 80%. The yield of transgenic plants was significantly higher upon ToLCNDV infection as compared to the non-transgenic plants. Although the natural resistance resources against ToLCNDV are not available, this work streamlines a novel amiRNA-based mechanism that may have the potential to develop viral resistance strategies in tomato, apart from its normal symptom development properties as it is targeting the conserved region against which higher accumulation of small interfering RNAs (siRNA) occurred in a naturally tolerant tomato cultivar.