CEPLAS Seminar

We are very happy that Pamela Ronald followed the invitation of our young researchers to visit CEPLAS!

Title: Engineering Tolerance to Stress and Resistance to Disease

Abstract:
Environmental stresses, particularly water availability and disease, are the largest factors determining plant yields and quality. The Ronald laboratory is studying the genetic basis of resistance to disease and tolerance to flooding in rice, the world’s most important staple food crop. Perception of extracellular signals by immune receptors is of central importance to eukaryotic survival. The rice immune receptor XA21, which confers resistance to most strains of the Gram-negative bacterium, Xanthomonas oryzae pv. oryzae (Xoo), is representative of a large class of cell surface receptors in plants and animals. We have recently identified an Xoo protein, called RaxX, which is required for activation of XA21-mediated immunity. Xoo strains lacking RaxX, or that carry mutations in the single RaxX tyrosine residue (Y41), are able to evade XA21-mediated immunity.

Each year millions of small farmers in the poorest areas of the world lose their entire crops to submergence. Most rice varieties will die if fully submerged for more than three days. Our team used positional cloning of the Submergence tolerance 1 quantitative trait locus and demonstrated it carried three ethylene response transcription factors (ERF). One of the ERFs, designated Sub1A, is upregulated rapidly in response to submergence and confers robust tolerance to submergence. This work revealed an important mechanism with which plants control tolerance to abiotic stress and set the stage for precision breeding and in-depth molecular-genetic analyses of Sub1A-mediated processes. In 2014, with support from the Bill and Melinda Gates Foundation, Sub1 rice has reached over 3.5 million farmers.