Plant immunity: Rice XA21-mediated resistance to bacterial infection

In this article, we describe the development of the plant immunity field, starting with efforts to understand the genetic basis for disease resistance, which similar to 30 y ago led to the discovery of diverse classes of immune receptors that recognize and respond to infectious microbes. We focus on knowledge gained from studies of the rice XA21 immune receptor that recognizes RaxX (required for activation of XA21 mediated immunity X), a sulfated microbial peptide secreted by the gram-negative bacterium Xanthomonas oryzae pv. oryzae. XA21 is representative of a large class of plant and animal immune receptors that recognize and respond to conserved microbial molecules. We highlight the complexity of this large class of receptors in plants, discuss a possible role for RaxX in Xanthomonas biology, and draw attention to the important role of sulfotyrosine in mediating receptor-ligand interactions.

Automated summary

This article describes the development of the field of plant immunity, focusing on the diverse classes of immune receptors and the specific case of the rice XA21 immune receptor. The article highlights the complexity of these receptors and discusses the potential role of a microbial peptide, RaxX, in Xanthomonas biology.