Plant Gene and Trait 2024, Vol.15, No.6, 314-322 http://genbreedpublisher.com/index.php/pgt 317 Figure 1OsGRF7is mainly repressed by OsmiR396e and expressed in various tissues (Adopted from Chen et al., 2020) Image caption: This figure appears to illustrate the regulation and expression pattern of the OsGRF7 gene in rice, particularly focusing on its repression by OsmiR396e and its expression across various tissues (Adopted from Chen et al., 2020) 5.2 Phenotypic analysis of GRA78 mutants Analyzing the phenotype of GRA78 mutants will help us better understand the role of this gene in rice growth and development. The leaves of GRA78 mutants are obviously white in the seedling stage, but as they grow, the leaves gradually return to green. This change is very sensitive to temperature, indicating that the function of GRA78 may be related to environmental changes. Studies have found that GRA78 is expressed in all tissues of rice, and the protein it encodes is located in chloroplasts, which is consistent with its important role in chloroplast development and operation. In addition, the expression levels of four OASTL homologous genes and five photosynthesis-related genes in the GRA78 mutant were significantly reduced, which further supports the view that GRA78 is involved in chloroplast biogenesis and photosynthesis (Hao et al., 2022). 5.3 Complementation studies and functional verification Complementation experiments have played a great role in verifying the function of GRA78. In the study by Wang et al. (2019), scientists introduced the normal GRA78 gene back into the mutant and successfully rescued the mutant’s albino phenotype. This proves that the observed problem is indeed caused by the LOC_Os01g59920 mutation. This complementation experiment not only verified the function of GRA78, but also emphasized its importance in chloroplast development and leaf color regulation. After the mutant returned to normal, it also showed that GRA78 has great potential in genetic improvement, especially in improving rice chloroplast function and enhancing stress resistance (Zhai et al., 2022). Overall, gene knockout, overexpression, mutant analysis and complementation experiments together confirmed the important role of GRA78 in rice chloroplast development and leaf color regulation. These research results also laid the foundation for future exploration of the molecular mechanism of GRA78 and its application in rice breeding (Figure 2) (Hu et al., 2020; Hao et al., 2022). 6 Comparative Analysis with Other Species 6.1 Homologous genes of GRA78 in other plants GRA78 is a cysteine synthase gene that has attracted attention because it can regulate the color of rice leaves. In fact, genes very similar to GRA78 have been found in many plants. Through genome comparison, scientists have found these homologous genes in Arabidopsis thaliana, maize (Zea mays) and wheat (Triticum aestivum). In Arabidopsis, these genes are related to chlorophyll synthesis, indicating that their functions are relatively
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