Plant cells are encased in a semi-rigid cell wall of complex build. As a consequence, cell wall remodeling is essential for the control of growth and development as well as the regulation of abiotic and biotic stress responses. Plant cells actively sense physico-chemical changes in the cell wall and initiate corresponding cellular responses. However, the underlying cell wall monitoring mechanisms remain poorly understood. In Arabidopsis the atypical receptor kinase STRUBBELIG (SUB) mediates tissue morphogenesis. Here, we show that SUB-mediated signal transduction also regulates the cellular response to a reduction in the biosynthesis of cellulose, a central carbohydrate component of the cell wall. SUB signaling affects early increase of intracellular reactive oxygen species, stress gene induction as well as ectopic lignin and callose accumulation upon exogenous application of the cellulose biosynthesis inhibitor isoxaben. Moreover, our data reveal that SUB signaling is required for maintaining cell size and shape of root epidermal cells and the recovery of root growth after transient exposure to isoxaben. SUB is also required for root growth arrest in mutants with defective cellulose biosynthesis. Genetic data further indicate that SUB controls the isoxaben-induced cell wall stress response independently from other known receptor kinase genes mediating this response, such as THESEUS1 or MIK2. We propose that SUB functions in a least two distinct biological processes: the control of tissue morphogenesis and the response to cell wall damage. Taken together, our results reveal a novel signal transduction pathway that contributes to the molecular framework underlying cell wall integrity signaling.

中文翻译：

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拟南芥受体激酶STRUBBELIG调节对纤维素缺乏的反应。

植物细胞被包裹在复杂构造的半刚性细胞壁中。因此，细胞壁重塑对于控制生长和发育以及调节非生物和生物应激反应至关重要。植物细胞主动感应细胞壁中的理化变化并启动相应的细胞反应。但是，基本的细胞壁监测机制仍然知之甚少。在拟南芥中，非典型受体激酶STRUBBELIG（SUB）介导组织形态发生。在这里，我们表明，SUB介导的信号转导也调节细胞对纤维素生物合成的减少的反应，纤维素是细胞壁的主要碳水化合物成分。SUB信号传导影响细胞内活性氧的早期增加，外源应用纤维素生物合成抑制剂异恶唑生时，应激基因诱导以及异位木质素和call质积累。此外，我们的数据表明，在短暂暴露于异恶唑酮后，SUB信号传导对于维持根表皮细胞的细胞大小和形状以及恢复根的生长是必需的。纤维素生物合成缺陷的突变体中，根生长停滞也需要SUB。遗传数据进一步表明，SUB可以独立于介导这种反应的其他已知受体激酶基因（例如THESEUS1或MIK2）独立控制异沙宾本诱导的细胞壁应激反应。我们建议SUB在至少两个不同的生物学过程中起作用：组织形态发生的控制和对细胞壁损伤的响应。在一起