TOM-DEF: Knocking out NRX expression in tomato - a boost to natural defences

Tomato is the next most important non-cereal crop after potato but yield losses due to fungal and bacterial diseases can be considerable. Although, the use of fungicides/bactericides can control such diseases, they have wider environmental effects so that they are only a short-term solution. A better strategy is to boost the crop's innate defences. I have previously helped to define a key regulatory defence node; nucleoredoxin (NRX) which suppresses oxygen and nitrogen free radical accumulation in the nucleus. However, this effect also suppresses defences against a wide-range of pathogens. This project will address the hypothesis that downward modulation of NRX expression will boost defence against disease. This will involve proof of principle work in tomato based on gene editing using CRISPR/Cas9 technology as well as generating plants that over-express NRX. The impact of NRX gene manipulation will be assessed in responses to economically important tomato pathogens; Rhizoctonia solani, Alternaria solani and Ralstonia. Solanacearum, Erwinia carotovora and Fusarium oxysporum. The project will focus on the well-established tomato cv. Moneymaker. Infected and uninfected plants will be imaged at the UK National Plant Phenomic Centre to provide digital description of the impact of NRX manipulation. The molecular effects of altered NRX expression will be assessed using transcriptomic and metabolomic data focusing on changes on infection and also fruit development. This omic data will be integrated into network models to understand the mechanism of NRX action in tomato. Outputs from the project will be CRISPR/Cas9 constructs and new lines with improved tomato defence against pathogens and proof of principle that NRX knockout can be exploited for commercial tomato production either through gene editing or transfer to non-transgenic approaches.