Raturi Arpit, Shekhar Shivam, Jha Ratnesh Kumar, Chauhan Divya, Pandey Saurabh, Kumari Sarita, Singh Ashutosh
Department of Agricultural Biotechnology and Molecular Biology, CBS&H, RPCAU-Pusa, Samastipur, Bihar, India.
Centre for Advanced Studies on Climate Change, RPCAU, Samastipur, Bihar, India.
Front Genet. 2024 Nov 5;15:1449113. doi: 10.3389/fgene.2024.1449113. eCollection 2024.
C4 crops have more efficient photosynthetic pathways that enable their higher photosynthetic capacities as well as nitrogen and water use efficiencies than C3 crops. Previous research has demonstrated that the genomes of C3 species include and express every gene needed for the C4 photosynthesis pathway. However, very little is known about the dynamics and evolutionary history of such genetic evolution in C4 plants. In this study, the genes encoding five key photosynthetic pathway enzymes in the genomes of C3 (rice), C4 (maize, sorghum, and foxtail millet), and CAM (pineapple) crops were identified and compared systematically. The numbers of genes in these photosynthetic enzymes were highest in the C4 crops like sorghum and foxtail millet, while only eight genes were identified in the CAM plant. However, 16 genes were identified in the C3 crop rice. Furthermore, we performed physical, chemical, gene structure and, cis-element analyses to obtain complete insights into these key genes. Tissue-specific expressions showed that most of the photosynthetic genes are expressed in the leaf tissues. Comparisons of the expression characteristics confirmed that the expression patterns of non-photosynthetic gene copies were relatively conserved among the species, while the C4 gene copies in the C4 species acquired new tissue expression patterns during evolution. Additionally, multiple sequence features that could affect C4 gene expressions and subcellular localization were found in the coding and promoter regions. Our research also highlights the variations in how different genes have evolved within the C4 photosynthetic pathway, and we confirmed that specific high expressions in the leaves and right distribution within the cells were crucial for the development of the C4 photosynthetic abilities. The findings of this study are expected to aid in understanding the evolutionary process of the C4 photosynthetic pathway in grasses as well as offer insights for modifying the C4 photosynthetic pathways in wheat, rice, and other significant C3 cereal crops.
C4作物具有更高效的光合途径，使其比C3作物具有更高的光合能力以及氮和水的利用效率。先前的研究表明，C3物种的基因组包含并表达C4光合作用途径所需的每个基因。然而，对于C4植物中这种基因进化的动态和进化历史知之甚少。在本研究中，系统地鉴定并比较了C3（水稻）、C4（玉米、高粱和谷子）和景天酸代谢（CAM）（菠萝）作物基因组中编码五种关键光合途径酶的基因。这些光合酶中的基因数量在高粱和谷子等C4作物中最高，而在CAM植物中仅鉴定出8个基因。然而，在C3作物水稻中鉴定出16个基因。此外，我们进行了物理、化学、基因结构和顺式元件分析，以全面了解这些关键基因。组织特异性表达表明，大多数光合基因在叶片组织中表达。表达特征的比较证实，非光合基因拷贝的表达模式在物种间相对保守，而C4物种中的C4基因拷贝在进化过程中获得了新的组织表达模式。此外，在编码区和启动子区发现了可能影响C4基因表达和亚细胞定位的多个序列特征。我们的研究还突出了不同基因在C4光合途径内进化方式的差异，并且我们证实，在叶片中的特定高表达和在细胞内的正确分布对于C4光合能力的发展至关重要。本研究的结果有望有助于理解禾本科植物中C4光合途径的进化过程，并为改造小麦、水稻和其他重要的C3谷类作物中的C4光合途径提供见解。
