Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China.
J Plant Physiol. 2013 Sep 15;170(14):1267-76. doi: 10.1016/j.jplph.2013.04.014. Epub 2013 Jun 5.
Root hairs are tip-growing long tubular outgrowths of specialized epidermal cells, and are important for nutrient and water uptake and interaction with the soil microflora. Here we characterized two poplar cellulose synthase-like D (CSLD) genes, PdCSLD5 and PdCSLD6, the most probable orthologs to the Arabidopsis AtCSLD3/KOJAK gene. Both PdCSLD5 and PdCSLD6 are strongly expressed in roots, including in the root hairs. Subcellular localization experiments showed that these two proteins are located not only in the polarized plasma membrane of root hair tips, but also in Golgi apparatus of the root hair and non-hair-forming cells. Overexpression of these two poplar genes in the atcsld3 mutant was able to rescue most of the defects caused by disruption of AtCSLD3, including root hair morphological changes, altered cell wall monosaccharide composition, increased non-crystalline β-1,4-glucan and decreased crystalline cellulose contents. Taken together, our results provide evidence indicating that PdCSLD5 and PdCSLD6 are functionally conserved with AtCSLD3 and support a role for PdCSLD5 and PdCSL6 specifically in crystalline cellulose production in poplar root hair tips. The results presented here also suggest that at least part of the mechanism of root hair formation is conserved between herbaceous and woody plants.
根毛是特化的表皮细胞顶端生长的管状突起，对于养分和水分的吸收以及与土壤微生物的相互作用非常重要。在这里，我们对两个杨树纤维素合酶类似 D（CSLD）基因，PdCSLD5 和 PdCSLD6 进行了表征，它们是拟南芥 AtCSLD3/KOJAK 基因最有可能的同源基因。PdCSLD5 和 PdCSLD6 在根中均强烈表达，包括根毛中。亚细胞定位实验表明，这两种蛋白质不仅位于根毛尖端的极化质膜上，而且位于根毛和非毛形成细胞的高尔基体中。在 atcsld3 突变体中过表达这两个杨树基因能够挽救 AtCSLD3 缺失引起的大多数缺陷，包括根毛形态变化、细胞壁单糖组成改变、非晶态β-1,4-葡聚糖增加和结晶纤维素含量降低。综上所述，我们的结果表明，PdCSLD5 和 PdCSLD6 在功能上与 AtCSLD3 保守，并支持 PdCSLD5 和 PdCSL6 在杨树根毛尖端的结晶纤维素产生中具有特定作用。本研究结果还表明，草本植物和木本植物之间的根毛形成机制至少有一部分是保守的。
