Cloning and functional study of OgXa13 in Oryza meyeriana

Bacterial blight is one of the most devastating bacterial diseases in rice production. The identification and utilization of resistance genes in rice breeding is the most economical and effective method for controlling this disease. Oryza meyeriana represents a valuable genetic resource due to its high resistance, and even immunity, to bacterial blight. In this study, we cloned the full-length cDNA and an 8908 bp genomic sequence of OgXa13, a homolog of OsXa13, from Oryza meyeriana using transcriptome and genome sequencing. Sequence analysis revealed that the gene structure of OgXa13 consists of five exons and four introns, mirroring the structure of rice OsXa13, and its core promoter sequence is identical to that of the rice susceptibility gene OsXa13. A total of 21 amino acid differences were observed between OgXa13 and OsXa13, with four key substitutions located in the MtN3.1 domain. Overexpression of OgXa13 and its introduction into TP309 plants via genetic transformation significantly enhanced resistance to bacterial blight. It is hypothesized that the amino acid sequence differences contribute to the distinct functions of the OgXa13 and OsXa13 proteins, suggesting that OgXa13 could be utilized as a dominant resistance gene in rice breeding. Furthermore, knockout of the OsXa13 gene using CRISPR/Cas9 in Nipponbare T1 homozygous lines also significantly enhanced resistance to bacterial blight, demonstrating that editing the susceptibility gene OsXa13 through CRISPR/Cas9 is an effective strategy for improving resistance. This study provides a valuable genetic resource and new insights for breeding rice with enhanced resistance to bacterial blight.