Silencing of the Rice Gene LRR1 Compromises Rice Xa21 Transcript Accumulation and XA21-Mediated Immunity

Abstract

Abstract Background The rice immune receptor XA21 confers resistance to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial leaf blight. We previously demonstrated that an auxilin-like protein, XA21 BINDING PROTEIN 21 (XB21), positively regulates resistance to Xoo. Results To further investigate the function of XB21, we performed a yeast two-hybrid screen. We identified 22 unique XB21 interacting proteins, including LEUCINE-RICH REPEAT PROTEIN 1 (LRR1), which we selected for further analysis. Silencing of LRR1 in the XA21 genetic background (XA21-LRR1Ri) compromises resistance to Xoo compared with control XA21 plants. XA21-LRR1Ri plants have reduced Xa21 transcript levels and reduced expression of genes that serve as markers of XA21-mediated activation. Overexpression of LRR1 is insufficient to alter resistance to Xoo in rice lines lacking XA21. Conclusions Taken together, our results indicate that LRR1 is required for wild-type Xa21 transcript expression and XA21-mediated immunity.

Keywords

• Rice
• Immunity
• Xanthomonas oryzae pv. oryzae
• XA21
• XB21
• LRR1