Recognition of dominant attractants by key chemoreceptors mediates recruitment of plant growth-promoting rhizobacteria
Recognition of dominant attractants by key chemoreceptors mediates recruitment of plant growth-promoting rhizobacteria
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关键化学感受器对显性引诱剂的识别介导促进植物生长的根际细菌的招募
DOI：
10.1111/1462-2920.14472
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发表时间：
2019-01-01
影响因子：
5.1
通讯作者：
Zhang, Ruifu
中科院分区：
文献类型：
--
作者：
Feng, Haichao;Zhang, Nan;Zhang, Ruifu
根际细菌对植物根系分泌物的趋化性是其高效定殖的前提。这是一个高度多因素的过程，因为根分泌物是复杂的化合物混合物，其组分被不同的化学感受器识别。关于根系分泌物及其受体中驱动定植相关趋化性的关键成分，信息很少。我们在这里提出了第一个全球性的评估，这一问题使用植物生长促进根际细菌（PGPR）芽孢杆菌velezensis SQR 9（原B。解淀粉酶）。这种菌株有效地殖民黄瓜根，在这里，我们表明，在这个过程中，趋化性黄瓜根分泌物是必不可少的。利用不同浓度的黄瓜根系分泌物、单个分泌物组分以及重组分泌物进行了趋化性测定，同时考虑到根系分泌物中检测到的浓度。结果表明，两个关键的化学感受器，McpA和McpC是必不可少的根分泌物的趋化和根定殖。两种受体均具有广泛的配体范围，并识别大多数已鉴定的渗出液关键组分（苹果酸、富马酸、葡萄糖酸和甘油酸、赖氨酸、丝氨酸、丙氨酸和甘露糖）。其余6个化学感受器没有贡献渗出液趋化性。这项研究为根际细菌趋化系统的进化提供了新的视角。
Chemotaxis to plant root exudates is supposed to be a prerequisite for efficient root colonization by rhizobacteria. This is a highly multifactorial process since root exudates are complex compound mixtures of which components are recognized by different chemoreceptors. Little information is available as to the key components in root exudates and their receptors that drive colonization related chemotaxis. We present here the first global assessment of this issue using the plant growth-promoting rhizobacterium (PGPR) Bacillus velezensis SQR9 (formerly B. amyloliquefaciens). This strain efficiently colonizes cucumber roots, and here, we show that chemotaxis to cucumber root exudates was essential in this process. We conducted chemotaxis assays using cucumber root exudates at different concentrations, individual exudate components as well as recomposed exudates, taking into account their concentrations detected in root exudates. Results indicated that two key chemoreceptors, McpA and McpC, were essential for root exudate chemotaxis and root colonization. Both receptors possess a broad ligand range and recognize most of the exudate key components identified (malic, fumaric, gluconic and glyceric acids, Lys, Ser, Ala and mannose). The remaining six chemoreceptors did not contribute to exudate chemotaxis. This study provides novel insight into the evolution of the chemotaxis system in rhizobacteria.