National Key Laboratory of Plant Molecular Genetics/CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
Mol Plant. 2013 Nov;6(6):1904-17. doi: 10.1093/mp/sst104. Epub 2013 Jun 14.
Endo-1,4-β-glucanases (EGases) are involved in many aspects of plant growth. Our previous study found that an EGase, PtrCel9A6, is specifically expressed in differentiating xylem cells during Populus secondary growth. In this study, the xylem-specific PtrCel9A6 was characterized for its role in xylem differentiation. The EGase is localized on the plasma membrane with catalytic domain toward the outside cell wall, hydrolyzing amorphous cellulose. Suppression of PtrCel9A6 expression caused secondary cell wall defects in xylem cells and significant cellulose reduction in Populus. Heterologous expression of PtrCel9A6 in Arabidopsis enhanced plant growth as well as increased fiber cell length. In addition, introduction of PtrCel9A6 into Arabidopsis resulted in male sterility due to defects in anther dehiscence. Together, these results demonstrate that PtrCel9A6 plays a critical role in remodeling the 1,4-β-glucan chains in the wall matrix and is required for cell wall thickening during Populus xylem differentiation.
内-1,4-β-葡聚糖酶（EGases）参与植物生长的许多方面。我们之前的研究发现，一种 EGase，PtrCel9A6，在杨树次生生长过程中特异性表达于正在分化的木质部细胞中。在这项研究中，我们对木质部特异性的 PtrCel9A6 进行了表征，以研究其在木质部分化中的作用。该 EGase 定位于质膜上，其催化结构域朝向细胞壁外侧，水解无定形纤维素。PtrCel9A6 表达的抑制导致木质部细胞次生细胞壁缺陷和杨树纤维素含量显著减少。PtrCel9A6 在拟南芥中的异源表达增强了植物的生长，同时增加了纤维细胞的长度。此外，PtrCel9A6 引入拟南芥中导致雄性不育，这是由于花药开裂缺陷所致。总之，这些结果表明 PtrCel9A6 在重塑细胞壁基质中的 1,4-β-葡聚糖链方面发挥着关键作用，并且在杨树木质部分化过程中细胞壁增厚是必需的。
