Rice Genomics and Genetics 2024, Vol.15, No.2, 48-57 http://cropscipublisher.com/index.php/rgg 51 genetic backgrounds, it may increase the difficulty of identifying genetic variation associated with a trait. Due to the global demand for high crop yields, elucidating the genetic control of rice architecture is critical. Rice structure is a complex trait affected by plant height, tillers, and panicle morphology, and is an important agronomic trait that determines yield. However, the complexity of this trait makes it difficult to elucidate the molecular mechanism. 4 Progress in GWAS Research on Rice Yield-Related Genes 4.1 Yield-related genes identified by GWAS Genome-wide association studies (GWAS) have been widely used to identify genes associated with rice yield. Yield is a complex trait that is affected by multiple genes, including genes that control sub-traits such as plant height, tillering (tillering), grain size, grain number, and maturity period. For example, the Gn1a gene affects the grain number of rice. It encodes a cytokine oxidase that affects the number of inflorescence branches and thus the number of grains in rice. The discovery of Gn1a helps to understand the genetic mechanism of rice yield formation and provides target genes for improving rice yield through molecular breeding. GS3 is one of the main genes that control rice grain size. Its different allelic variations are related to differences in grain length, thereby affecting rice yield. The discovery of the GS3 gene provides the possibility to regulate grain size through molecular breeding; DEP1 gene and the panicle density of rice is related. Its allelic variation affects the panicle structure of rice, thereby affecting yield. Specific DEP1 mutations can lead to a denser panicle structure, increase the number of grains, and increase yield; the Ghd7 gene affects the maturity period and yield of rice. It is one of the important genes that controls the length of the rice growth cycle and can regulate the flowering time and grain number of rice. Different Ghd7 allelic variations can lead to different growth cycles and yield performances, which are extremely important for the development of rice varieties adapted to different planting environments; and the qSW5 gene affects the grain width and thousand-grain weight of rice. Variations in this gene can lead to significant changes in grain morphology, thereby affecting yield (Song et al., 2015). The discovery of these genes not only deepens our understanding of the genetic basis of rice yield, but also provides specific targets for improving rice varieties through molecular breeding techniques. Through the yield-related genes identified by GWAS, researchers can edit or select specific genes to develop new rice varieties with higher yields and stronger adaptability. However, it is worth noting that the phenotypic effects and environmental interactions of these genes need to be considered in the actual breeding process to ensure the success of variety improvement. 4.2 Functions and regulatory mechanisms of these genes The Gn1a gene is a key gene that controls rice grain number. It encodes a cytokine oxidase (cytokinin oxidase/dehydrogenase, CKX), which is responsible for decomposing cytokines. Cytokines are a type of plant hormones that play an important role in plant growth, development and tillering. Gn1a affects tiller number and inflorescence development by regulating the levels of cytokines, thereby indirectly affecting grain number. The lower the expression level of the Gn1a gene, the lower the activity of decomposing cytokines, and the higher the concentration of cytokines, which promotes the formation of more tillers and inflorescences, thereby increasing the number of grains. The GS3 gene mainly affects rice grain size and is a pleiotropic gene. Its different allelic variations are related to significant differences in grain length. The GS3 gene encodes a protein containing a membrane-binding domain that controls the final size of the grain by negatively regulating cell proliferation in the early stages of rice grain development. Certain allelic variations of GS3 may reduce its function, leading to increased cell division activity, thereby producing larger grains (Weng et al., 2018). DEP1 gene is related to rice panicle density, and specific allelic variations can significantly affect panicle structure and grain number. TheDEP1 gene encodes a signal transduction component involved in regulating plant branching patterns. Rice with enhanced DEP1 allelic variation exhibits a denser panicle structure, which is achieved by promoting the formation of branch points and increasing the number of branches, thereby improving
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