Regulation of the α-expansin gene OsEXPA8 expression affects root system architecture in transgenic rice plants
Regulation of the α-expansin gene OsEXPA8 expression affects root system architecture in transgenic rice plants
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DOI：
10.1007/s11032-014-0016-4
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发表时间：
2014-01
影响因子：
3.1
通讯作者：
Ying Wang;Nana Ma;Shichun Qiu;Hanyan Zou;G. Zang;Z. Kang;Guixue Wang;Junli Huang
中科院分区：
文献类型：
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作者：
Ying Wang;Nana Ma;Shichun Qiu;Hanyan Zou;G. Zang;Z. Kang;Guixue Wang;Junli Huang
Expansins是一种细胞壁蛋白，通过细胞外基质的松弛参与控制植物的生长，并由一个大的基因家族编码。然而，与单个基因功能丧失有关的数据仍然有限，这些基因支持扩展蛋白在根生长中的作用。在本研究中，我们利用RNAi技术对水稻α-Expansin基因OsEXPA8的生物学功能进行了研究。在水稻中抑制OsEXPA8的表达显著损害了根系构型和植株的生长，导致主根变短，侧根变少。相应地，根维管束的细胞大小急剧减小。值得注意的是，OsEXPA8的沉默损害了根毛的伸长；此外，株高明显降低。OsEXPA8-GFP在洋葱表皮细胞中的瞬时表达证实了OsEXPA8位于细胞壁上。OsEXPA8主要在一周龄的水稻幼苗的根和地上部表达，在氯化钠诱导下高度表达，但在硝酸盐和磷酸盐饥饿下受到抑制。此外，利用原子力显微镜研究了OsEXPA8蛋白减少引起的细胞壁纳米力学的变化，结果表明，OsEXPA8沉默的悬浮细胞的壁刚性(杨氏模数)显著增加。综上所述，我们的结果表明，OsEXPA8对根系构型是至关重要的，这支持了Exansins通过介导细胞壁松弛而促进植物生长的假说。
Expansins are cell wall proteins implicated in the control of plant growth via loosening of the extracellular matrix, and are encoded by a large gene family. However, data linked to loss of function of single genes which support the role of expansins in root growth remain limited. In this study, we used RNA interference to examine the biological functions of the rice α-expansin geneOsEXPA8. Repression ofOsEXPA8expression in rice impaired the root system architecture and plant growth significantly, leading to shorter primary roots and fewer lateral roots. Accordingly, the cell size of the root vascular bundle reduced drastically. Notably,OsEXPA8silencing impaired root hair elongation; moreover, plant height was clearly reduced. Transient expression of OsEXPA8-GFP in onion epidermal cells verified that OsEXPA8 is located on the cell wall.OsEXPA8was expressed predominantly in the root and shoot of one-week-old rice seedlings, and highly induced by NaCl but suppressed by nitrate and phosphate starvation. In addition, atomic force microscopy was used to explore alterations in cell wall nanomechanics caused by OsEXPA8 protein reduction, which showed that the wall stiffness (Young’s modulus) ofOsEXPA8-silenced suspension cells was increased significantly. Taken together, our results suggest thatOsEXPA8is critical for root system architecture, which supports the hypothesis that expansins are involved in enhancing plant growth by mediating cell wall loosening.