Zhao Xin, Jiang Xuemei, Li Zeyu, Song Qin, Xu Changzhen, Luo Keming
Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, School of Life Sciences, Southwest University, Chongqing, China.
Lab of Plant Cell Engineering, Southwest University of Science and Technology, Mianyang, Sichuan, China.
Front Plant Sci. 2023 Jul 21;14:1232880. doi: 10.3389/fpls.2023.1232880. eCollection 2023.
Jasmonic acid (JA) is a phytohormone involved in plant defense, growth, and development, etc. However, the regulatory mechanisms underlying JA-mediated lignin deposition and secondary cell wall (SCW) formation remain poorly understood. In this study, we found that JA can inhibit lignin deposition and SCW thickening in poplar trees through exogenous MeJA treatment and observation of the phenotypes of a JA synthesis mutant, . Hence, we identified a JA signal inhibitor PtoJAZ5, belonging to the TIFY gene family, which is involved in the regulation of secondary vascular development of . RT-qPCR and GUS staining revealed that was highly expressed in poplar stems, particularly in developing xylem. Overexpression of inhibited SCW thickening and down-regulated the expression of SCW biosynthesis-related genes. Further biochemical analysis showed that PtoJAZ5 interacted with multiple SCW switches NAC/MYB transcription factors, including MYB3 and WND6A, through yeast two-hybrid and bimolecular fluorescent complementation experiments. Transcriptional activation assays demonstrated that MYB3-PtoJAZ5 and WND6A-PtoJAZ5 complexes regulated the expression of lignin synthetic genes. Our results suggest that PtoJAZ5 plays a negative role in JA-induced lignin deposition and SCW thickening in poplar and provide new insights into the molecular mechanisms underlying JA-mediated regulation of SCW formation.
茉莉酸（JA）是一种参与植物防御、生长和发育等过程的植物激素。然而，JA介导的木质素沉积和次生细胞壁（SCW）形成的调控机制仍知之甚少。在本研究中，我们通过外源茉莉酸甲酯（MeJA）处理和观察JA合成突变体的表型，发现JA可抑制杨树中的木质素沉积和SCW增厚。因此，我们鉴定出一种属于TIFY基因家族的JA信号抑制剂PtoJAZ5，它参与调控杨树的次生维管发育。逆转录定量聚合酶链反应（RT-qPCR）和GUS染色显示，PtoJAZ5在杨树茎中高度表达，尤其是在发育中的木质部。PtoJAZ5的过表达抑制了SCW增厚，并下调了SCW生物合成相关基因的表达。进一步的生化分析表明，通过酵母双杂交和双分子荧光互补实验，PtoJAZ5与多个SCW开关NAC/MYB转录因子相互作用，包括MYB3和WND6A。转录激活分析表明，MYB3-PtoJAZ5和WND6A-PtoJAZ5复合物调控木质素合成基因的表达。我们的结果表明，PtoJAZ5在JA诱导的杨树木质素沉积和SCW增厚中起负作用，并为JA介导的SCW形成调控的分子机制提供了新的见解。
