Xiao Chaowen, Zhang Tian, Zheng Yunzhen, Cosgrove Daniel J, Anderson Charles T
Center for Lignocellulose Structure and Formation (C.X., T.Z., Y.Z., D.J.C., C.T.A.) and Department of Biology (C.X., T.Z., D.J.C., C.T.A.), The Pennsylvania State University, University Park, Pennsylvania 16802.
Center for Lignocellulose Structure and Formation (C.X., T.Z., Y.Z., D.J.C., C.T.A.) and Department of Biology (C.X., T.Z., D.J.C., C.T.A.), The Pennsylvania State University, University Park, Pennsylvania 16802
Plant Physiol. 2016 Jan;170(1):234-49. doi: 10.1104/pp.15.01395. Epub 2015 Nov 2.
Xyloglucan constitutes most of the hemicellulose in eudicot primary cell walls and functions in cell wall structure and mechanics. Although Arabidopsis (Arabidopsis thaliana) xxt1 xxt2 mutants lacking detectable xyloglucan are viable, they display growth defects that are suggestive of alterations in wall integrity. To probe the mechanisms underlying these defects, we analyzed cellulose arrangement, microtubule patterning and dynamics, microtubule- and wall-integrity-related gene expression, and cellulose biosynthesis in xxt1 xxt2 plants. We found that cellulose is highly aligned in xxt1 xxt2 cell walls, that its three-dimensional distribution is altered, and that microtubule patterning and stability are aberrant in etiolated xxt1 xxt2 hypocotyls. We also found that the expression levels of microtubule-associated genes, such as MAP70-5 and CLASP, and receptor genes, such as HERK1 and WAK1, were changed in xxt1 xxt2 plants and that cellulose synthase motility is reduced in xxt1 xxt2 cells, corresponding with a reduction in cellulose content. Our results indicate that loss of xyloglucan affects both the stability of the microtubule cytoskeleton and the production and patterning of cellulose in primary cell walls. These findings establish, to our knowledge, new links between wall integrity, cytoskeletal dynamics, and wall synthesis in the regulation of plant morphogenesis.
木葡聚糖构成了双子叶植物初生细胞壁中大部分的半纤维素，并在细胞壁结构和力学方面发挥作用。尽管缺乏可检测到的木葡聚糖的拟南芥（Arabidopsis thaliana）xxt1 xxt2突变体能够存活，但它们表现出生长缺陷，这表明细胞壁完整性发生了改变。为了探究这些缺陷背后的机制，我们分析了xxt1 xxt2植物中的纤维素排列、微管模式和动态、与微管和细胞壁完整性相关的基因表达以及纤维素生物合成。我们发现，纤维素在xxt1 xxt2细胞壁中高度排列，其三维分布发生了改变，并且在黄化的xxt1 xxt2下胚轴中微管模式和稳定性异常。我们还发现，xxt1 xxt2植物中微管相关基因（如MAP70-5和CLASP）以及受体基因（如HERK1和WAK1）的表达水平发生了变化，并且xxt1 xxt2细胞中的纤维素合酶运动性降低，这与纤维素含量的降低相对应。我们的结果表明，木葡聚糖的缺失会影响微管细胞骨架的稳定性以及初生细胞壁中纤维素的产生和模式。据我们所知，这些发现建立了细胞壁完整性、细胞骨架动态和细胞壁合成在植物形态发生调控中的新联系。
