Hua Xiuting, Shi Huihong, Zhuang Gui, Lan Yuhong, Zhou Shaoli, Zhao Dongxu, Lyu Ming-Ju Amy, Akbar Sehrish, Liu Jia, Yuan Yuan, Li Zhen, Jiang Qing, Huang Kaixin, Zhang Yating, Zhang Qing, Wang Gang, Wang Yu, Yu Xiaomin, Li Pinghua, Zhang Xingtan, Wang Jianping, Xiao Shenghua, Yao Wei, Ming Ray, Zhu Xin-Guang, Zhang Muqing, Tang Haibao, Zhang Jisen
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Laboratory of Sugarcane Biology, Guangxi University, Nanning, Guangxi 530004, China.
Center for Genomics and Biotechnology, National Sugarcane Engineering Technology Research Center, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
Plant Physiol. 2024 Dec 2;196(4):2685-2700. doi: 10.1093/plphys/kiae455.
In agronomically important C4 grasses, efficient CO2 delivery to Rubisco is facilitated by NADP-malic enzyme (C4NADP-ME), which decarboxylates malate in bundle sheath cells. However, understanding the molecular regulation of the C4NADP-ME gene in sugarcane (Saccharum spp.) is hindered by its complex genetic background. Enzymatic activity assays demonstrated that decarboxylation in sugarcane Saccharum spontaneum predominantly relies on the NADP-ME pathway, similar to sorghum (Sorghum bicolor) and maize (Zea mays). Comparative genomics analysis revealed the recruitment of 8 core C4 shuttle genes, including C4NADP-ME (SsC4NADP-ME2), in the C4 pathway of sugarcane. Contrasting to sorghum and maize, the expression of SsC4NADP-ME2 in sugarcane is regulated by different transcription factors (TFs). We propose a gene regulatory network for SsC4NADP-ME2, involving candidate TFs identified through gene coexpression analysis and yeast 1-hybrid experiment. Among these, ABA INSENSITIVE5 (ABI5) was validated as the predominant regulator of SsC4NADP-ME2 expression, binding to a G-box within its promoter region. Interestingly, the core element ACGT within the regulatory G-box was conserved in sugarcane, sorghum, maize, and rice (Oryza sativa), suggesting an ancient regulatory code utilized in C4 photosynthesis. This study offers insights into SsC4NADP-ME2 regulation, crucial for optimizing sugarcane as a bioenergy crop.
在具有重要农艺价值的C4禾本科植物中，NADP - 苹果酸酶（C4NADP - ME）促进了二氧化碳向核酮糖-1,5-二磷酸羧化酶（Rubisco）的有效输送，该酶在维管束鞘细胞中使苹果酸脱羧。然而，甘蔗（Saccharum spp.）复杂的遗传背景阻碍了对C4NADP - ME基因分子调控的理解。酶活性测定表明，甘蔗野生种（Saccharum spontaneum）中的脱羧作用主要依赖于NADP - ME途径，这与高粱（Sorghum bicolor）和玉米（Zea mays）相似。比较基因组学分析揭示了在甘蔗的C4途径中招募了8个核心C4穿梭基因，包括C4NADP - ME（SsC4NADP - ME2）。与高粱和玉米不同，甘蔗中SsC4NADP - ME2的表达受不同转录因子（TFs）调控。我们提出了一个SsC4NADP - ME2的基因调控网络，涉及通过基因共表达分析和酵母单杂交实验鉴定的候选TFs。其中，ABA不敏感5（ABI5）被证实是SsC4NADP - ME2表达的主要调节因子，它与启动子区域内的一个G - 盒结合。有趣的是，调控G - 盒内的核心元件ACGT在甘蔗、高粱、玉米和水稻（Oryza sativa）中是保守的，这表明在C4光合作用中使用了一种古老的调控密码。这项研究为SsC4NADP - ME2的调控提供了见解，这对于将甘蔗优化为生物能源作物至关重要。
