The widespread adoption of hybrid rice has played a pivotal role in ensuring food security in China. However, the heavy reliance on wild-abortive (WA) cytoplasmic male sterility (CMS) systems raises potential biosafety concerns. In this study, we screened a global collection of wild rice (Oryza rufipogon) accessions using orf182-specific molecular markers to characterize the geographic distribution patterns of this gene. Mitochondrial sequencing and assembly of 11 representative wild rice species harboring orf182 revealed 16 novel genes. A total of 469 mitochondrial genes were classified into 23 gene families, with nine families containing single-copy homologous genes, indicating significant gene duplication in mitochondria. We observed a strong positive correlation between mitochondrial genome size and the quantity and size of repetitive sequences. Collinearity analysis revealed extensive mitochondrial variation and large-scale inversions in Guangdong wild rice. Comparative genome analysis uncovered inversions, translocations, and several variations surrounding orf182, with a 71 bp repeat sequence mediating the formation of the orf182-nad6 chimeric gene. Gene copy number analysis (GCNV) revealed variable orf182 gene copy counts (1, 2, and 3) in wild rice species. Additionally, successful transformation of orf182 from various sources into sterile lines was achieved. These findings provide valuable resources for advancing hybrid rice development in China, thus contributing to enhanced food security.
Long et al. (2026) studied this question.