Lessons from natural variations: artificially induced heading date variations for improvement of regional adaptation in rice.

KEY MESSAGE: New strategy of breeding by modulating key heading date gene Ehd1 to enhance the variations of heading date regardless of genetic background for better adaptation to local environment in rice. Flowering time (or heading date) is an important quantitative trait in rice (Oryza sativa) that determines its adaptation to specific cultivation areas and growing seasons. However, breeding of flowering time is currently relying on laborious selections and combinations of different alleles of various genes. Here, we cloned a cis-variant allele of Ehd1 that regulated not only heading date but also yield potential. Genetic analysis revealed that Ehd1 acted downstream of Ghd7 as a negative regulator of yield potential, and expression divergence of Ehd1 negatively correlates with phenotype variations including heading date and grain yield. Moreover, regardless of genetic background, manipulations of the expression of a single gene, Ehd1, are sufficient for recreating beneficial heading date variations which could be subjected to the selection of best suitable lines for local environment conditions. Beyond a deeper understanding of transcriptional control of quantitative traits, this study provided an effective and flexible strategy for breeding rice cultivars to maximize grain production for any region of cultivation.