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

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.