Department of Wood Science, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
J Integr Plant Biol. 2015 Apr;57(4):396-410. doi: 10.1111/jipb.12353.
Cell walls are vital to the normal growth and development of plants as they protect the protoplast and provide rigidity to the stem. Here, two poplar and Arabidopsis orthologous endoglucanases, which have been proposed to play a role in secondary cell wall development, were examined. The class B endoglucanases, PtGH9B5 and AtGH9B5, are secreted enzymes that have a predicted glycosylphosphatidylinositol anchor, while the class C endoglucanases, PtGH9C2 and AtGH9C2, are also predicted to be secreted but instead contain a carbohydrate-binding module. The poplar endoglucanases were expressed in Arabidopsis using both a 35S promoter and the Arabidopsis secondary cell wall-specific CesA8 promoter. Additionally, Arabidopsis t-DNA insertion lines and an RNAi construct was created to downregulate AtGH9C2 in Arabidopsis. All of the plant lines were examined for changes in cell morphology and patterning, growth and development, cell wall crystallinity, microfibril angle, and proportion of cell wall carbohydrates. Misregulation of PtGH9B5/AtGH9B5 resulted in changes in xylose content, while misregulation of PtGH9C2/AtGH9C2 resulted in changes in crystallinity, which was inversely correlated with changes in plant height and rosette diameter. Together, these results suggest that these endoglucanases affect secondary cell wall development by contributing to the cell wall crystallization process.
细胞壁对于植物的正常生长和发育至关重要，因为它们保护原生质体并为茎提供刚性。在这里，研究了两种杨树和拟南芥的同源内切葡聚糖酶，它们被认为在次生细胞壁发育中发挥作用。B 类内切葡聚糖酶 PtGH9B5 和 AtGH9B5 是分泌酶，具有预测的糖基磷脂酰肌醇锚定，而 C 类内切葡聚糖酶 PtGH9C2 和 AtGH9C2 也被预测为分泌酶，但含有碳水化合物结合模块。使用 35S 启动子和拟南芥次生细胞壁特异性 CesA8 启动子，在拟南芥中表达了杨树内切葡聚糖酶。此外，还创建了拟南芥 t-DNA 插入系和 RNAi 构建体，以在拟南芥中下调 AtGH9C2。所有植物系都检查了细胞形态和图案、生长和发育、细胞壁结晶度、微纤维角和细胞壁碳水化合物比例的变化。PtGH9B5/AtGH9B5 的调控异常导致木糖含量的变化，而 PtGH9C2/AtGH9C2 的调控异常导致结晶度的变化，这与植物高度和莲座叶直径的变化呈反比。总之，这些结果表明这些内切葡聚糖酶通过参与细胞壁结晶过程来影响次生细胞壁的发育。
