Inactivation of the Phosphatase CheZ Alters Cell-Surface Properties of Azorhizobium caulinodans ORS571 and Symbiotic Association with Sesbania rostrata
Inactivation of the Phosphatase CheZ Alters Cell-Surface Properties of Azorhizobium caulinodans ORS571 and Symbiotic Association with Sesbania rostrata
复制标题
磷酸酶 CheZ 失活改变了固氮根瘤菌 ORS571 的细胞表面特性以及与田菁的共生关系
DOI：
10.1094/mpmi-05-19-0143-r
复制
发表时间：
2019-11-01
影响因子：
3.5
通讯作者：
Xie, Zhihong
中科院分区：
文献类型：
--
作者：
Liu, Xiaolin;Xie, Zhihong
茎瘤固氮根瘤菌能与寄主田菁形成根茎根瘤。CheZ磷酸酶在A. caulinodans的趋化性途径以前使用非趋化性cheZ突变株（AC601）进行了探索。该突变体表现出更强的附着到根表面，增强早期定殖，但是，这并没有导致增加的繁殖效率。在本研究中，我们进一步研究了CheZ在菌株ORS571与其寄主植物根相互作用中的作用。通过追踪LacZ标记的cheZ突变体的长期定殖动态，发现在此过程中，cheZ突变体的定殖率下降。此外，cheZ突变体不能在根表面自由扩散，并且在最初的定殖位点逐渐被野生型超越。定量逆转录PCR分析表明，exp基因编码胞外多糖的合成，包括oac3，高度表达的cheZ突变体。构建携带cheZ和oac3缺失的菌株导致在定殖过程中缺陷的突变菌株，其缺陷程度与oac3单突变菌株相同。这一结果表明，cheZ突变体的增强的定殖可以通过调节胞外多糖的形成来实现。这表明了趋化蛋白在根瘤菌与宿主植物相互作用中的重要性，并扩展了我们对根瘤菌与宿主植物共生相互作用的认识。
Azorhizobium caulinodans can form root and stem nodules with the host plant Sesbania rostrata. The role of the CheZ phosphatase in the A. caulinodans chemotaxis pathway was previously explored using the nonchemotactic cheZ mutant strain (AC601). This mutant displayed stronger attachment to the root surface, enhancing early colonization; however, this did not result in increased nodulation efficiency. In this study, we further investigated the role of CheZ in the interaction between strain ORS571 and the roots of its host plant. By tracking long-term colonization dynamic of cheZ mutant marked with LacZ, we found a decrease of colonization of the cheZ mutant during this process. Furthermore, the cheZ mutant could not spread on the root surface freely and was gradually outcompeted by the wild type in original colonization sites. Quantitative reverse-transcription PCR analyses showed that exp genes encoding exopolysaccharides synthesis, including oac3, were highly expressed in the cheZ mutant. Construction of a strain carrying a deletion of both cheZ and oac3 resulted in a mutant strain defective in the colonization process to the same extent as found with the oac3 single-mutant strain. This result suggested that the enhanced colonization of the cheZ mutant may be achieved through regulating the formation of exopolysaccharides. This shows the importance of the chemotactic proteins in the interaction between rhizobia and host plants, and expands our understanding of the symbiosis interaction between rhizobium and host plant.