ZmXa21-L gene encodes a plant receptor-like kinases (RLKs) protein that enhances resistance to bacterial blight in rice

Abstract

Abstract Rice bacterial blight, which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most serious rice diseases worldwide. The rice Xa21 gene encodes plant receptor-like kinases (RLKs) that confer broad-spectrum resistance against Xoo. In this study, a full-length cDNA encoding a putative RLK protein with high sequence homology to the rice Xa21 gene was isolated from maize and designated as ZmXa21-L. The full-length cDNA of ZmXa21-L contained a 2796 bp open reading frame encoding a precursor protein of 932 amino acid residues. Comparative and bioinformatics analyses revealed that ZmXa21-L showed a high degree of homology with other Xa21-like proteins and contained the leucine-rich repeat domain, transmembrane region, and serine/threonine kinase domain. Subcellular localization revealed the presence of ZmXa21-L in the cell membrane. The expression level of ZmXa21-L was significantly induced by wounding, salicylic acid, and jasmonate treatments. ZmXa21-L was transformed into rice under the control of a ubiquitin promoter. After inoculation with Xoo strains, ZmXa21-L transgenic rice showed enhanced resistance to bacterial blight compared with wild-type rice. Moreover, investigation of the agronomic traits revealed that the ZmXa21-L expression increased the panicle number and grain yield per plant in the transgenic rice. Results demonstrate that ZmXa21-L is a promising candidate gene in transgenic breeding for bacterial blight resistance and crop improvement.