Hiding inside each plant cell, protein complexes encoded by disease resistance genes are like sleeping armies, waking up and activating defenses when harmful pathogens such as fungi or bacteria are detected. Such genes encode traits used by agricultural biotechnologists to generate disease-resistant crops, and plant biologists are striving to illuminate every aspect of how they work -- much of which remains shrouded in mystery.

In new research published in the journal Science, a team of biologists, including Colorado State University Assistant Professor of Biology Marc Nishimura, have shed new light on a crucial aspect of the plant immune response. Their discovery, revealing how plant resistance proteins trigger localized cell death, could lead to new strategies for engineering disease resistance in next-generation crops.

The research team was led by Nishimura, Jeff Dangl of the University of North Carolina at Chapel Hill, and Jeffrey Milbrandt of the Washington University School of Medicine. Nishimura started the work as a research scientist in the lab of Erin Osborne Nishimura, CSU assistant professor in the Department of Biochemistry and Molecular Biology.

Together with colleagues, Nishimura identified the mechanism of one little-understood domain of plant resistance proteins called a "toll-interleukin-1 receptor," or TIR domain. The team showed that during the plant immune response, the TIR domain is an enzyme that degrades a molecule called NAD+, which is essential for metabolism in all organisms. By cleaving NAD+, the plant self-destructs infected cells while leaving others unharmed.

Read on: https://www.sciencedaily.com/releases/2019/08/190822141903.htm