Key message

Cortical microtubule arrays are the primary mechanism for guiding the re-orientation of cellulose microfibrils and determining MFA in secondary cell wall of wood fibre and tracheid cells in reaction wood.

Abstract

Microtubules are directly and indirectly involved in guiding cellulose synthase complexes (CSCs) through the plasma membrane. The angle of cellulose deposition is a critical response to environmental signals and/or stress conditions, and particularly crucial during reaction wood formation, a process in which woody plants deposit additional cell wall material to counteract gravitational forces. Tubulin genes are upregulated in response to gravitational stimulus during reaction wood formation, which can result in changes to microtubule assembly. In this study, microtubules were visualised in three woody tree species (two angiosperms: Eucalyptus globulus Labill., Populus alba L., and one gymnosperm: Pinus radiata D. Don.) using immunofluorescence to quantitatively evaluate microtubule organisation during reaction wood formation. Our results suggest that reorientation of the cortical microtubule array affects secondary cell wall deposition, even across different types of reaction wood, by ensuring context-appropriate orientation of cellulose microfibrils and determining MFA in wood cells. Pharmacological studies conducted on in vitro cultured stem segments or in vivo during reaction wood formation corroborated these important roles for microtubules during wood development. This study starts to unveil the role of tubulins during wood formation by exploring cortical microtubule array organisation in trees subjected to gravitational stimulus and it sheds light on cellular and molecular mechanisms behind cellulose deposition in tree species.

中文翻译：

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反应木材形成过程中的皮质微管动力学确保木本树木中纤维素微纤维角度适合环境

关键信息

皮质微管阵列是引导纤维素微纤维重新定向和测定木纤维次生细胞壁和反应木管胞细胞中 MFA 的主要机制。

抽象的

微管直接和间接参与引导纤维素合酶复合物（CSC）穿过质膜。纤维素沉积的角度是对环境信号和/或应激条件的关键响应，在反应木材形成过程中尤其重要，在该过程中，木本植物沉积额外的细胞壁材料以抵消重力。在反应木形成过程中，微管蛋白基因响应重力刺激而上调，这可能导致微管组装的变化。在本研究中，使用免疫荧光技术对三种木本树种（两种被子植物：蓝桉、白杨和一种裸子植物：辐射松）中的微管进行可视化，以定量评估反应木材形成过程中的微管组织。我们的结果表明，皮质微管阵列的重新定向会影响次生细胞壁沉积，甚至在不同类型的反应木材中，通过确保纤维素微纤维的上下文适当的方向并确定木材细胞中的 MFA。在体外培养的茎段或反应木材形成过程中进行的体内药理学研究证实了微管在木材发育过程中的重要作用。这项研究通过探索受到重力刺激的树木中的皮质微管阵列组织，开始揭示微管蛋白在木材形成过程中的作用，并揭示了树种中纤维素沉积背后的细胞和分子机制。