Structure-Function Analysis of Nod Factor-Induced Root Hair Calcium Spiking in Rhizobium-Legume Symbiosis1
Structure-Function Analysis of Nod Factor-Induced Root Hair Calcium Spiking in Rhizobium-Legume Symbiosis1
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DOI：
10.1104/pp.010690
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发表时间：
2002-05
期刊：
影响因子：
7.4
通讯作者：
R. Wais;D. Keating;S. Long
中科院分区：
文献类型：
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作者：
R. Wais;D. Keating;S. Long
在根瘤菌-豆科植物共生中，相容的细菌和宿主植物通过信号交换相互作用：宿主化合物促进细菌生物合成结瘤（结瘤）基因的表达，从而产生脂壳寡糖信号，即Nod因子（NF）。给定的根瘤菌物种携带的特定的 nod 基因阵列决定了合成的 NF 结构并定义了细菌识别的豆科植物宿主的范围。即使在没有活根瘤菌的情况下，纯化的 NF 也可以诱导早期宿主反应已知的最早的宿主对 NF 的反应之一是根毛细胞中细胞质钙的振荡行为，或钙尖峰，最初在苜蓿属中观察到。随后在其他四个属中进行了表征（D.W. Ehrhardt、R. Wais、S.R. Long [1996] Cell 85：673-681；S.A. Walker、V. Viprey、J.A. Downie [2000] Proc Natl Acad Sci USA 97：13413-13418；D.W. Ehrhardt、J.A. Downie、J.哈里斯，R.J. S.R.长的、未发表的数据）。我们试图确定活根瘤菌是否会引发快速的钙尖峰反应以及该反应是否依赖于 NF。我们发现，在苜蓿中华根瘤菌与蒺藜苜蓿的相互作用中，细菌引起的钙尖峰反应与对纯化的 NF 的反应没有区别。我们确定钙加标是点头基因依赖性宿主反应。对蒺藜苜蓿和苜蓿 (Medicago sativa) 中钙离子添加的研究也揭示了早期 NF 信号转导中存在差异的可能性。我们进一步证明了thenod 基因通过使用经改造表达11S 的大肠杆菌BL21 (DE3) 诱导钙尖峰的充分性。苜蓿点头基因。
In the Rhizobium-legume symbiosis, compatible bacteria and host plants interact through an exchange of signals: Host compounds promote the expression of bacterial biosynthetic nod(nodulation) genes leading to the production of a lipochito-oligosaccharide signal, the Nod factor (NF). The particular array of nod genes carried by a given species ofRhizobium determines the NF structure synthesized and defines the range of legume hosts by which the bacterium is recognized. Purified NF can induce early host responses even in the absence of live Rhizobium One of the earliest known host responses to NF is an oscillatory behavior of cytoplasmic calcium, or calcium spiking, in root hair cells, initially observed in Medicago spp. and subsequently characterized in four other genera (D.W. Ehrhardt, R. Wais, S.R. Long [1996] Cell 85: 673–681; S.A. Walker, V. Viprey, J.A. Downie [2000] Proc Natl Acad Sci USA 97: 13413–13418; D.W. Ehrhardt, J.A. Downie, J. Harris, R.J. Wais, and S.R. Long, unpublished data). We sought to determine whether live Rhizobium trigger a rapid calcium spiking response and whether this response is NF dependent. We show that, in the Sinorhizobium meliloti-Medicago truncatula interaction, bacteria elicit a calcium spiking response that is indistinguishable from the response to purified NF. We determine that calcium spiking is a nod gene-dependent host response. Studies of calcium spiking in M. truncatula and alfalfa (Medicago sativa) also uncovered the possibility of differences in early NF signal transduction. We further demonstrate the sufficiency of thenod genes for inducing calcium spiking by usingEscherichia coli BL21 (DE3) engineered to express 11S. meliloti nod genes.