Chou Minxia, Xia Congcong, Feng Zhao, Sun Yali, Zhang Dehui, Zhang Mingzhe, Wang Li, Wei Gehong
State Key Laboratory of Crop Stress Biology in Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, China.
Plant Mol Biol. 2016 Mar;90(4-5):389-402. doi: 10.1007/s11103-015-0424-9. Epub 2015 Dec 28.
Translationally controlled tumor protein (TCTP) is fundamental for the regulation of development and general growth in eukaryotes. Its multiple functions have been deduced from its involvement in several cell pathways, but its potential involvement in symbiotic nodulation of legumes cannot be suggested a priori. In the present work, we identified and characterized from the woody leguminous tree Robinia pseudoacacia a homolog of TCTP, Rpf41, which was up-regulated in the infected roots at 15 days post-inoculation but decreased in the matured nodules. Subcellular location assay showed that Rpf41 protein was located in the plasma membrane, cytoplasm, nucleus, and also maybe in cytoskeleton. Knockdown of Rpf41 via RNA interference (RNAi) resulted in the impaired development of both nodule and root hair. Compared with wild plants, the root and stem length, fresh weight and nodule number per plant was decreased dramatically in Rpf41 RNAi plants. The number of ITs or nodule primordia was also significantly reduced in the Rpf41 RNAi roots. The analyses of nodule ultrastructure showed that the infected cell development in Rpf41 RNAi nodules remained in zone II, which had fewer infected cells. Furthermore, the symbiosomes displayed noticeable shrinkage of bacteroid and peribacteroid space enlargement in the infected cells of Rpf41 RNAi nodules. In the deeper cell layers, a more remarkable aberration of the infected cell ultrastructure was observed, and electron-transparent lesions in the bacteroid cytoplasm were detected. These results identify TCTP as an important regulator of symbiotic nodulation in legume for the first time, and it may be involved in symbiotic cell differentiation and preventing premature aging of the young nodules in R. pseudoacacia.
翻译调控肿瘤蛋白（TCTP）对于真核生物的发育和整体生长调节至关重要。其多种功能是从它参与多种细胞途径推导出来的，但它在豆科植物共生结瘤中的潜在作用并不能先验地推测出来。在本研究中，我们从木本豆科植物刺槐中鉴定并表征了TCTP的一个同源物Rpf41，它在接种后15天的受感染根中上调，但在成熟根瘤中减少。亚细胞定位分析表明，Rpf41蛋白位于质膜、细胞质、细胞核中，也可能存在于细胞骨架中。通过RNA干扰（RNAi）敲低Rpf41导致根瘤和根毛发育受损。与野生植物相比，Rpf41 RNAi植物的根和茎长度、鲜重以及单株根瘤数显著降低。Rpf41 RNAi根中的侵染线或根瘤原基数量也显著减少。根瘤超微结构分析表明，Rpf41 RNAi根瘤中的受感染细胞发育停留在区域II，该区域受感染细胞较少。此外，共生体在Rpf41 RNAi根瘤的受感染细胞中显示出明显的类菌体收缩和类菌体周空间扩大。在更深的细胞层中，观察到受感染细胞超微结构有更明显的畸变，并且在类菌体细胞质中检测到电子透明损伤。这些结果首次确定TCTP是豆科植物共生结瘤的重要调节因子，并且它可能参与共生细胞分化并防止刺槐幼根瘤过早衰老。
