Nakamura Masato, Nozaki Mamoru, Iwata Yuji, Koizumi Nozomu, Sato Yasushi
Biology and Environmental Science, Graduate School of Science and Engineering, Ehime University, Matsuyama, Ehime 790-8577, Japan.
Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.
Plant Biotechnol (Tokyo). 2022 Jun 25;39(2):129-138. doi: 10.5511/plantbiotechnology.21.1224a.
Endoplasmic reticulum (ER) stress activates unfolded protein responses (UPRs), such as promoting protein folding under the control of specific gene expression. Our previous study showed that ER stress induced by ER stress inducers such as tunicamycin (Tm), an inhibitor of -linked glycan synthesis, causes ectopic lignin deposition in Arabidopsis roots, but the relationship between UPR and ectopic lignin deposition remains unclear. The receptor-like kinase THESEUS1 (THE1) has been shown to sense cell wall damage (CWD) induced in Arabidopsis by cellulose synthase inhibitors such as isoxaben (ISO) and to activate ectopic lignin deposition. In this study, we assessed the involvement of THE1 in ectopic lignin deposition caused by the ER stress inducer Tm. The loss-of-function mutation of , , suppressed Tm-induced root growth inhibition and ectopic lignin deposition, revealing that THE1 is involved in root growth defects and ectopic lignin deposition caused by ER stress. Similarly, ISO treatment induced ectopic lignin deposition as well as the expression of the UPR marker genes () and (). Conversely, in the mutant, ISO-induced ectopic lignin deposition and the expression of and were suppressed. These results showed that THE1 is involved in not only root growth inhibition and ectopic lignin deposition caused by ER stress but also CWD-induced UPR.
内质网（ER）应激会激活未折叠蛋白反应（UPR），比如在特定基因表达的调控下促进蛋白质折叠。我们之前的研究表明，由衣霉素（Tm）等内质网应激诱导剂引发的内质网应激，衣霉素是一种N-连接聚糖合成抑制剂，会导致拟南芥根中出现异位木质素沉积，但UPR与异位木质素沉积之间的关系仍不清楚。类受体激酶THESEUS1（THE1）已被证明能感知拟南芥中由异恶草松（ISO）等纤维素合酶抑制剂诱导的细胞壁损伤（CWD），并激活异位木质素沉积。在本研究中，我们评估了THE1在由内质网应激诱导剂Tm引起的异位木质素沉积中的作用。the1的功能缺失突变抑制了Tm诱导的根生长抑制和异位木质素沉积，表明THE1参与了内质网应激引起的根生长缺陷和异位木质素沉积。同样，ISO处理诱导了异位木质素沉积以及UPR标记基因bip1和bip2的表达。相反，在the1突变体中，ISO诱导的异位木质素沉积以及bip1和bip2的表达受到抑制。这些结果表明，THE1不仅参与内质网应激引起的根生长抑制和异位木质素沉积，还参与CWD诱导的UPR。
