Blue light inhibits immune response of potato to late blight disease

Daylight is made from a spectrum of wavelengths and plants possess receptors that can detect red and blue light. Blue light is important for plant growth and yet inhibits the immune response of potato plants to Phytophthora infestans, making them more susceptible to potato late blight, a research team featuring plant scientists from the James Hutton Institute and the University of Dundee has discovered.

The finding is critical for food security because potato late blight is a historically relevant plant disease, responsible for the Irish potato famine in the 19th century, and still causes millions of pounds in annual losses to the potato industry.  

The scientific team, led by Professor Paul Birch of the University of Dundee, identified a signalling pathway in potato plant cells that negatively regulates immunity to the late blight pathogen, when stimulated with blue light.

P infestans, the pathogen responsible for late blight, delivers a number of proteins into the host plant to manipulate host systems and cause disease. The research team found that one of these proteins binds to an important control point between the plant’s response to blue light and immunity to late blight.

Professor Paul Birch, Head of Plant Sciences at Dundee University and the senior author on the study said: “We have found that blue light suppresses the normal immune response in the plant which results in more severe late blight disease.

This advance highlights that varying light treatments can directly impact not only plant growth and development but also the ability of plants to fight off disease."

Professor Derek Stewart, director of the Institute’s Advanced Plant Growth Centre, commented: “This research is an example of the kind of game-changing agricultural technologies that are at the heart of the Advanced Plant Growth Centre. Identifying new, non-chemical routes to modulating pest and disease damage and losses, here possibly via a breeding to modulate the response to blue light, are part of our aim to develop sustainable and low carbon routes to sustainable food production.”