Kim Yeonjoon, Kim Boyeong, Kang Jinku, Bae Sang-Il, Yoon Hyeryung, Shin Hee-Ji, Lee Ji-Young, Paek Nam-Chon, Kang Kiyoon
Department of Agriculture, Forestry and Bioresources, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea.
School of Biological Sciences, Seoul National University, Seoul, South Korea.
Plant J. 2025 Sep;123(5):e70469. doi: 10.1111/tpj.70469.
Salt stress impairs photosynthetic efficiency and consequently reduces the growth, development, and grain yield of crop plants. The formation of hydrophobic barriers in the root endodermis, including the suberin lamellae and Casparian strips, is a key adaptive strategy for salt stress tolerance. In this study, we identified the role of the rice NAC transcription factor, ONAC005, in salt stress tolerance. ONAC005 expression was induced by NaCl and abscisic acid (ABA). Expression analysis using the β-glucuronidase reporter gene driven by the ONAC005 promoter revealed that ONAC005 is predominantly expressed in the stele and endodermis of rice roots. The null mutation of ONAC005 increased sodium ion levels in the shoots and roots, indicating susceptibility to salt stress, whereas ONAC005 overexpression enhanced tolerance to salt stress by reducing sodium ion accumulation. Yeast one-hybrid, chromatin immunoprecipitation, and dual-luciferase assays demonstrated that ONAC005 upregulates the expression of trehalose-6-phosphate synthase 8 (OsTPS8) by directly binding to its promoter region, leading to increased trehalose accumulation. ONAC005 enhances the formation of the root hydrophobic barrier by upregulating OsTPS8 expression under salt stress. Furthermore, considering the altered expression of ABA signaling and responsive genes, ONAC005 regulates the expression of genes in specific stress-responsive pathways that are independent of OsTPS8-mediated signaling. These results indicate that ONAC005 positively regulates hydrophobic barrier formation in the roots, thereby enhancing salt stress tolerance in rice.
盐胁迫会损害光合效率，进而降低作物的生长、发育和籽粒产量。在根内皮层形成疏水屏障，包括木栓质层和凯氏带，是耐盐胁迫的关键适应性策略。在本研究中，我们确定了水稻NAC转录因子ONAC005在耐盐胁迫中的作用。ONAC005的表达受NaCl和脱落酸（ABA）诱导。使用由ONAC005启动子驱动的β-葡萄糖醛酸酶报告基因进行的表达分析表明，ONAC005主要在水稻根的中柱和内皮层中表达。ONAC005的无效突变增加了地上部和根部的钠离子水平，表明对盐胁迫敏感，而ONAC005的过表达通过减少钠离子积累增强了对盐胁迫的耐受性。酵母单杂交、染色质免疫沉淀和双荧光素酶测定表明，ONAC005通过直接结合海藻糖-6-磷酸合酶8（OsTPS8）的启动子区域上调其表达，导致海藻糖积累增加。在盐胁迫下，ONAC005通过上调OsTPS8的表达增强根疏水屏障的形成。此外，考虑到ABA信号传导和响应基因的表达变化，ONAC005调节特定应激响应途径中与OsTPS8介导的信号传导无关的基因表达。这些结果表明，ONAC005正向调节根中疏水屏障的形成，从而增强水稻的耐盐胁迫能力。
