Heading date is a critical physiological process in rice that is influenced by both genetic and environmental factors. The photoperiodic pathway is a primary regulatory mechanism for rice heading, with key florigen genes Hd3a (Heading date 3a) and RFT1 (RICE FLOWERING LOCUS T1) playing central roles. Upstream regulatory pathways, including Hd1 and Ehd1, also significantly impact this process. This review aims to provide a comprehensive examination of the localization, cloning, and functional roles of photoperiodic pathway-related genes in rice, and to explore the interactions among these genes as well as their pleiotropic effects on heading date. We systematically review recent advancements in the identification and functional analysis of genes involved in the photoperiodic pathway. We also discuss the molecular mechanisms underlying rice heading date variation and highlight the intricate interactions between key regulatory genes. Significant progress has been made in understanding the molecular mechanisms of heading date regulation through the cloning and functional analysis of photoperiod-regulating genes. However, the regulation of heading date remains complex, and many underlying mechanisms are not yet fully elucidated. This review consolidates current knowledge on the photoperiodic regulation of heading date in rice, emphasizing novel findings and gaps in the research. It highlights the need for further exploration of the interactions among flowering-related genes and their response to environmental signals. Despite advances, the full regulatory network of heading date remains unclear. Further research is needed to elucidate the intricate gene interactions, transcriptional and post-transcriptional regulatory mechanisms, and the role of epigenetic factors such as histone methylation in flowering time regulation. This review provides a detailed overview of the current understanding of photoperiodic pathway genes in rice, setting the stage for future research to address existing gaps and improve our knowledge of rice flowering regulation.

Rice heterosis has played a significant role in improving rice yields in China since the 1970s. The utilization of heterosis between the indica and japonica subspecies of rice is especially important in this regard. However, inter-subspecies hybridization between indica and japonica rice is hampered by the inadequate seed-setting rate and inferior rice quality of hybrid offspring, which has limited its development. The discovery and cloning of wide-compatibility gene S5-n and the granular starch synthase gene Wx have provided a solution to this problem, paving the way for the breeding of inter-subspecies hybrid rice. Here we demonstrated the breeding process of Zheyou810 and its performances in regional trials. Employing marker-assisted selection through the utilization of KASP (Kompetitive Allele-Specific PCR), a high-yielding and superior-quality indica–japonica hybrid rice variety named Zheyou810 was developed. Zheyou810 achieved an average yield of 10,737.75 kg/ha (12.58% higher than control Jiayou5) in the national regional trials across 2019 and 2020, and 11,777.25 kg/ha (13.36% higher than Jiayou5) in the production trial in 2020, respectively. The quality of rice has also been improved, reaching the standards set by the Ministry of Agriculture of the People’s Republic of China for Grade 3 premium rice (NY/T593). In 2021, Zheyou810 was approved by the national examination showing broad application prospects.