Durable resistance gene Xa4 encodes a cell wall-associated kinase

Xa4 is a durable rice disease resistance gene that confers resistance against Xanthomonas oryzae pv. oryzae (Xoo), causal agent of bacterial blight. Hu et al. show that Xa4 encodes a wall-associated kinase (WAK) that promotes cellulose synthesis and suppresses wall loosening, thereby strengthening the cell wall. Suppression of disease is due to Xa4’s effects on cell wall integrity. Furthermore, Xa4 is associated with shorter stature, a beneficial agronomic trait that helps prevent lodging. As the authors say, “The simultaneous improvement of multiple agronomic traits conferred by Xa4 may account for its widespread and lasting utilization in rice breeding programmes globally.” Nature Plants 10.1038/nplants.2017.9