Abstract: INTRODUCTION: Bacterial blight is one of the three major diseases that threaten global rice production, seriously affecting the yield and quality of rice. The identification and utilization of resistance genes is one of the most effective ways to control bacterial blight.  RATIONALE: To identify quantitative trait locus (QTL) related to bacterial blight resistance in rice, this study used the indica rice HZ, the japonica rice Nekken2 and their 120 recombinant inbred lines (RILs) as experimental materials. Four different pathotypes of bacterial blight were inoculated at the tillering stage of rice and the resistance phenotypes were evaluated.  RESULTS: Based on the high-density genetic map constructed previously, 19 QTLs were detected, with the maximum limit of detection (LOD) value being 5.49. Candidate genes within the detected QTL intervals were screened and their expression levels were analyzed by qRT-PCR. LOC_Os02g13410 and LOC_Os04g01320, which are related to the regulatory pathway of STK receptor protein, showed significant upregulated expression after inoculation treatment. Meanwhile, the expression levels of the MYB transcription factor family gene LOC_Os05g10690 and the gene LOC_Os01g12320 related to the lipase regulatory pathway of GDSL-like lipase/acylhydrolase showed an extremely significant increase after inoculation treatment. The expression levels of the candidate genes LOC_Os02g13270, LOC_Os02g13410, LOC_Os02g13420, LOC_Os02g13430 and LOC_Os01g12130 were significantly different between the two parents and were induced after inoculation with the bacterial blight pathogen.   CONCLUSION: It was found that these candidate genes are presumed to be key candidate genes for regulating resistance to bacterial blight. The above results lay a foundation for the fine mapping and cloning of bacterial blight resistance-related genes and are of great significance for breeding rice varieties with broad-spectrum resistance to diseases.

Key words: Oryza sativa, bacterial blight, QTL mapping, candidate genes