Rice THIN CULM 4 (TC4) modulates culm strength by regulating morphology, structure, and development

Culm strength is crucial for rice growth, nutrition transportation, and structural resilience, which are essential for lodging resistance and stable production. In this study, we identified a rice thin culm mutant tc4, characterized by thinner culms and thicker cavity walls, resulting in weakened culm mechanical strength. Using map-based cloning, the candidate gene was isolated, and complementation and CRISPR/Cas9 experiments confirmed that a single nucleotide substitution in TC4 is responsible for the thin and brittle culm phenotype. TC4, a homolog of the FLORICAULA/LEAFY gene, localizes to the nucleus and cytoplasm. Further research revealed that TC4 regulates culm development by influencing plant hormones and sugar transport. This research not only advances our understanding of rice culm regulation, but also provides valuable insights for breeding lodging-resistant rice varieties.