Latest Discovery Part of Pioneering History in Plant Signaling at WSU

PULLMAN, Wash. – The recent discovery by Washington State University scientists that a barley plant can detect an invader and within five minutes start to build its resistance to attack is just the latest in a long, fruitful history of research regarding the ways plants communicate.

It was while monitoring the activity of combined resistance genes in barley that Andy Kleinhofs, professor of molecular genetics, and Assistant Research Professor Jayaveeramuthu Nirmala observed and documented “communication” between the barley plants and stem rust spores. In the process, the researchers identified the proteins recognized by the Rpg1 resistance gene and saw the series of signals that tell the plant to protect itself. Their work was published in the Proceedings of the National Academy of Science on Aug. 30 this year.

“WSU is a pioneer in the science of plant signaling,” said Ralph Cavalieri, associate dean and director of the WSU Agricultural Research Center. “WSU scientists have been, and continue to be, at the forefront of increasing our understanding of plant communication.”

Consider, for example, the work of the late WSU Professor Clarence (Bud) Ryan.

Ryan pioneered the study of what has come to be known as the “innate immune response” of plants. A protein chemist by trade, in the early 1970s he began trying to understand how plant protease inhibitors work. Those are natural insecticides, made by plants, which prevent insects and microorganisms from digesting plant material.

Prior to his work, plants were assumed to contain the inhibitors all the time, as a deterrent to being eaten. Ryan discovered instead that plants make the inhibitors in response to an attack. He further showed that an attack on one part of a plant sets off chemical signals that spur production of inhibitors throughout the entire plant.

Regents Professor B.W. (Joe) Poovaiah deciphered the role that salicylic acid, a close chemical relative of aspirin, plays as a signal molecule that kicks off a series of reactions that help plants defend against external threats. Poovaiah established that in controlling salicylic acid level, calcium acts like a gatekeeper within the cells of a plant, directing incoming information and helping the plant respond to such dangers as pathogen attacks. Normal, healthy plants have a low level of SA in their cells. That level rises when the plant is threatened by infection or environmental stress.

More recently, Assistant Professor Michael Neff’s research focuses on clarifying how multiple signaling pathways converge to regulate seedling responses to light as well as adult plant development. This research also addresses the biological mechanisms controlling multiple traits which have been proposed as targets for enhanced plant biomass production including; photoreceptor-mediated shade avoidance, leaf senescence, leaf size, flower/fruit size and stem diameter.