Cry1Ac-mediated resistance to tomato leaf miner (Tuta absoluta) in tomato

Abstract

Tomato leaf miner (Tuta absoluta) is a major pest of tomato in regions with hot climates such as South America and the Mediterranean. This insect feeds on almost every part of the plant and forms galleries while feeding on the plant’s inner tissues. Thus, it can cause plant death and is costly and difficult to control with chemical sprays. In this study, we transferred a modified Bacillus thuringiensis cry1Ac gene to tomato plants via Agrobacterium tumefaciens mediated transformation. Introduction of the cry1Ac gene to the tomato genome was confirmed with PCR and Southern blot analysis in 12 independent events. Insertion sites of the transgene in the tomato genome were determined with TAIL-PCR (thermal asymmetric interlaced polymerase chain reaction) for four selected transgenic lines. Cry1Ac gene expression was verified at both the transcriptional and translational levels, with RT-qPCR and Western blot analyses, respectively. Expression of the Cry1Ac protein in tomato resulted in T. absoluta mortality rates of 38–100% depending on transgenic line. In addition, gallery formation was reduced in 57–100% of the transgenic plants. Moreover, it was found that a single copy of the gene in the hemizygous condition is sufficient to confer tolerance to leaf miner. This is the first reported development of tomato plants resistant to T. absoluta. These transgenic plants are promising for development of commercial tomato cultivars resistant to leaf miner, which will limit the use of environmentally harmful chemicals for control of this pest.