The heading date, a critical trait influencing the rice yield and quality, has always been a hot topic in breeding research. Appropriately delaying the flowering time of excellent northern rice varieties is of great significance for improving yields and enhancing regional adaptability during the process for introducing varieties from north to south. In this study, genes influencing the heading date were identified through genome-wide association studies (GWAS). Using KenDao 12 (K12), an excellent cultivar from northern China, as the material, the specific flowering activator, OsMADS50, was edited using the genome-editing method to regulate the heading date to adapt to the southern planting environment. The results indicated that the osmads50 mutant line of K12 flowered about a week later, with a slight increase in the yield and good adaptability in the southern region in China. Additionally, the expressions of key flowering regulatory genes, such as Hd1, Ghd7, Ehd1, Hd3a, and RFT1, were reduced in the mutant plants, corroborating the delayed flowering phenotype. Yield trait analysis revealed that the primary factor for improved yield was an increase in the number of effective tillers, although there is potential for further enhancements in the seed-setting rate and grain plumpness. Furthermore, there were significant increases in the length-to-width ratio of the rice grains, fat content, and seed transparency, all contributing to an overall improvement in the rice quality. In summary, this study successfully obtained a rice variety with a delayed growth period through OsMADS50 gene editing, effectively implementing the strategy for adapting northern rice varieties to southern climates. This achievement significantly supports efforts to enhance the rice yield and quality as well as to optimize production management practices.

Photosynthesis and tillering number have been essential components determining grain yield in rice. However, the genetic mechanism of carotenoid biosynthesis pathway, which is one of the photosynthetic pigments of rice, affecting tillering of rice is rarely studied. This study elucidates the roles of OsFT in photosynthesis and carotenoid biosynthesis, and the synergistic regulation of rice tillering by SL and ABA, providing a theoretical basis for breeding high-yielding, drought-resistant rice varieties. The OsFT gene was cloned using map-based cloning technology. Quantitative RT-PCR and RNA sequencing (RNA-seq) were conducted to identify differentially expressed genes. Molecular technologies, including yeast two-hybrid assay (Y2H), co-immunoprecipitation assay (Co-IP), bimolecular fluorescence complementation assays (BIFC), and LUC complementation imaging assay (LCI) were employed to investigate the physical interaction between OsFT and OsFtsh2. High-performance liquid chromatography (HPLC) was used to measure the levels of abscisic acid (ABA), strigolactone (SL), and all-trans-β-carotene in rice plants. Data for yield-related traits were statistically analyzed and processed using Microsoft Excel, and the data were analysed using GraphPad Prism version 9. We report that OsFT interacts with the photosynthetic protein OsFtsh2 to maintain the stability of the photosynthetic system by regulating the degradation and renewal of photosynthetic protein, thus affecting photosynthetic efficiency and stress adaptability. It was found that OsFT regulates the expression of ABA and SL by influencing the carotenoid biosynthesis pathway, which in turn affects tillering. In addition, overexpression of OsFT enhances plant adaptability to drought stress and increases plant yield. OsFT interacts with OsFtsH2 to maintain the stability of the photosynthetic system and affects tillering by regulating the expression of ABA and SL. Biological studies have found that overexpressing this gene can enhance the plant's drought tolerance and yield.