State Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Plant Cell. 2023 Aug 2;35(8):2871-2886. doi: 10.1093/plcell/koad130.
Plants have evolved sophisticated mechanisms to coordinate their growth and stress responses via integrating various phytohormone signaling pathways. However, the precise molecular mechanisms orchestrating integration of the phytohormone signaling pathways remain largely obscure. In this study, we found that the rice (Oryza sativa) short internodes1 (shi1) mutant exhibits typical auxin-deficient root development and gravitropic response, brassinosteroid (BR)-deficient plant architecture and grain size as well as enhanced abscisic acid (ABA)-mediated drought tolerance. Additionally, we found that the shi1 mutant is also hyposensitive to auxin and BR treatment but hypersensitive to ABA. Further, we showed that OsSHI1 promotes the biosynthesis of auxin and BR by activating the expression of OsYUCCAs and D11, meanwhile dampens ABA signaling by inducing the expression of OsNAC2, which encodes a repressor of ABA signaling. Furthermore, we demonstrated that 3 classes of transcription factors, AUXIN RESPONSE FACTOR 19 (OsARF19), LEAF AND TILLER ANGLE INCREASED CONTROLLER (LIC), and OsZIP26 and OsZIP86, directly bind to the promoter of OsSHI1 and regulate its expression in response to auxin, BR, and ABA, respectively. Collectively, our results unravel an OsSHI1-centered transcriptional regulatory hub that orchestrates the integration and self-feedback regulation of multiple phytohormone signaling pathways to coordinate plant growth and stress adaptation.
植物已经进化出复杂的机制，通过整合各种植物激素信号通路来协调生长和应激反应。然而，精确的分子机制协调植物激素信号通路的整合在很大程度上仍然不清楚。在这项研究中，我们发现水稻（Oryza sativa）短节间 1（shi1）突变体表现出典型的生长素缺乏型根发育和向重力性反应、油菜素内酯（BR）缺乏型植物结构和粒大小以及增强的脱落酸（ABA）介导的耐旱性。此外，我们还发现 shi1 突变体对生长素和 BR 处理的反应也较低，但对 ABA 的反应较高。进一步，我们表明 OsSHI1 通过激活 OsYUCCAs 和 D11 的表达来促进生长素和 BR 的生物合成，同时通过诱导 ABA 信号转导抑制剂 OsNAC2 的表达来抑制 ABA 信号转导。此外，我们还证明了 3 类转录因子，AUXIN RESPONSE FACTOR 19（OsARF19）、LEAF AND TILLER ANGLE INCREASED CONTROLLER（LIC）和 OsZIP26 和 OsZIP86，直接结合到 OsSHI1 的启动子上，并分别响应生长素、BR 和 ABA 调节其表达。总之，我们的结果揭示了一个以 OsSHI1 为中心的转录调控枢纽，协调了多种植物激素信号通路的整合和自我反馈调节，以协调植物的生长和应激适应。
