Understanding disease development of tomato brown rugose fruit virus (ToBRFV)

ToBRFV is a contact transmitted tomato (and pepper) infecting virus against which there is no known genetic resistance in tomato. The virus is robust and previous work has shown the virus to be both thermally and environmentally stable, retaining infectivity for many weeks outside of an infected plant. Grower experience in the UK has raised questions on symptom expression under UK conditions in UK grown varieties, with symptoms in some cases being less severe than expected. The aim of this project is to investigate the development of disease in two varieties commonly grown in the UK. This will be done by mimicking both a winter and spring cropping cycle, and in each case replicating an early infection at the point where plants enter the glasshouse and also infection into a more mature crop imitating infection being introduced during crop growth. The study will use a combination of symptom observation and validated laboratory diagnostics to measure development of disease over time. The study will also look to ascertain best practice sampling advice for different plant parts, to confirm initial work in the Netherlands suggesting mature leaves may not be reliable for detection of ToBRFV from infected plants.

The aim of the project is to assess the reactions of common tomato varieties to infection with ToBRFV under UK growing conditions.

There are three core project objectives to:

• Investigate the expression of disease caused by ToBRFV in UK grown varieties under UK (research facility) growing conditions through symptom observation
• Investigate development of infection of ToBRFV over time from infected plants using molecular diagnostic techniques, comparing infections at different growth stages and different growth cycles (winter and spring crop)
• Investigate where and when to sample plants for reliable diagnostic results throughout the infection cycle.