Heat stress during the reproductive stage, especially during flowering, can considerably diminish grain yield of rice (Oryza sativa L.). A meta-QTL analysis provides a powerful and stable approach to identify QTLs, regardless of the genetic background of the mapping population and the environmental conditions. In the presented research, 95 previously published QTLs underwent MQTL analysis, recognizing 37 most consistent MQTLs across the different genetic backgrounds and panels. The 30 MQTLs identified had narrow confidence intervals (<5 cM), with 20 having attributed over 10% of phenotypic variance, ranging from 2.4% to 40.55%. In 37 MQTLs, 10 main candidate genes representing 10 gene families were successful for selection based on high R² values. Two genes, LOC_Os02g04710 (OsOSC2) and LOC_Os06g05550 (OsGELP74), distinctly appeared with elevated transcript levels in the panicle tissue. The haplotype analysis revealed two rare haplotypes (H017 and H018) for OsOSC2, distinguishing indica and japonica. At the same time, OsGELP74 was evident across several accessions, with only one rare haplotype (H006) representing indica, tropical japonica, temperate japonica, and admixed accessions. The identification of such novel haplotypes associated with key heat-stress-related traits can help accelerate the development of heat-stress-tolerant rice genotypes in Vietnam.
Rice (O. sativa L.), accessions, 3K RG, haplotype analysis, MQTL, rice heat tolerance, genetic backgrounds, phenotypic variance
In rice (O. sativa L.), heat stress at the flowering stage severely reduces the grain yield, demanding targeted breeding for stable and heat-tolerant germplasm. Meta-QTL analysis identified the key genes and validated haplotype-based breeding for the development of heat-stress-tolerant rice genotypes in Vietnam.