Ruan Nan, Xu Hai, Chen Kaixuan, Tian Fuhao, Gao Deyuan, Wang Zihan, Yang Xiao, Yan Xia, Wang Ye, Wang Meihan, Dang Zhengjun, Yin Xuelin, Tang Yijun, Xu Quan, Li Fengcheng, Chen Wenfu
Key Laboratory of Crop Physiology, Ecology, Genetics and Breeding, Ministry of Agriculture, Shenyang Agricultural University, Shenyang, China.
Department of Resources and Environment, Zunyi Normal College, Zunyi, China.
Rice (N Y). 2025 Feb 22;18(1):8. doi: 10.1186/s12284-025-00764-w.
Salt stress limits plant growth and agricultural productivity and plants have evolved suitable mechanisms to adapt to salinity environments. It is important to characterize genes involved in plant salt tolerance, which will advance our understanding of mechanisms mediating salt tolerance and help researchers design ways to improve crop performances under high salinity environments. Here, we reported a CYP450 family member, CYP75B4, improves salt tolerance of rice seedlings by inducing flavonoid tricin and cell wall lignin accumulation. The CYP75B4 is highly expressed in tissues rich in cell walls and induced by salt treatment. Subcellular localization analysis revealed that CYP75B4 is localized in the endoplasmic reticulum (ER). The CYP75B4 overexpressing (CYP75B4-OE) lines showed significant enhancement in stem mechanical strength, whereas the cyp75b4 null mutants displayed weaker stems, as compared to the wild-type. Notably, the cyp75b4 and CYP75B4-OE lines showed decreased and improved, respectively, salt tolerance performances in terms of survival rate, ROS accumulation, and Na/ K homeostasis. Additionally, the cyp75b4 mutants had a decreased tricin level, whereas CYP75B4-OE lines showed an increased tricin content, under both control or salinity conditions. Furthermore, treating the cyp75b4 mutants with tricin partly resorted salt stress tolerance to the wild-type levels, indicating a role of CYP75B4-mediated tricin production in rice response to salinity. Consistently, another tricin-deficient mutant cyp93g1 also displayed salt sensitivity and the tricin application could partly restore its salt-sensitive phenotypes. Moreover, the CYP75B4 significantly promotes lignin deposition in cell walls of mature stems and seedlings under salinity conditions, which probably contributes to the enhanced stem mechanical strength and improved salt tolerance in CYP75B4-OE plants. Our findings reveal a novel function of CYP75B4 in rice salt tolerance and lodging resistance by inducing tricin accumulation and lignin deposition in cell walls.
盐胁迫限制了植物生长和农业生产力，而植物已经进化出了适应盐环境的合适机制。表征参与植物耐盐性的基因很重要，这将增进我们对介导耐盐性机制的理解，并帮助研究人员设计提高高盐环境下作物性能的方法。在此，我们报道了一个细胞色素P450家族成员CYP75B4，它通过诱导黄酮类化合物小麦黄素和细胞壁木质素积累来提高水稻幼苗的耐盐性。CYP75B4在富含细胞壁的组织中高度表达，并受盐处理诱导。亚细胞定位分析表明CYP75B4定位于内质网（ER）。与野生型相比，过表达CYP75B4（CYP75B4-OE）的株系茎的机械强度显著增强，而cyp75b4基因敲除突变体的茎较弱。值得注意的是，就存活率、活性氧积累和钠/钾稳态而言，cyp75b4和CYP75B4-OE株系分别表现出耐盐性降低和提高。此外，在对照或盐度条件下，cyp75b4突变体的小麦黄素水平降低，而CYP75B4-OE株系的小麦黄素含量增加。此外，用小麦黄素处理cyp75b4突变体可部分将盐胁迫耐受性恢复到野生型水平，表明CYP75B4介导的小麦黄素产生在水稻对盐度的响应中起作用。同样，另一个小麦黄素缺陷突变体cyp93g1也表现出盐敏感性，施用小麦黄素可部分恢复其盐敏感表型。此外，在盐度条件下，CYP75B4显著促进成熟茎和幼苗细胞壁中木质素的沉积，这可能有助于增强CYP75B4-OE植物的茎机械强度和提高耐盐性。我们的研究结果揭示了CYP75B4通过诱导细胞壁中小麦黄素积累和木质素沉积在水稻耐盐性和抗倒伏性方面的新功能。
