The model legume Medicago truncatula possesses a single outward Shaker K⁺ channel, whereas Arabidopsis thaliana possesses two channels of this type, named AtSKOR and AtGORK, with AtSKOR having been shown to play a major role in K⁺ secretion into the xylem sap in the root vasculature and with AtGORK being shown to mediate the efflux of K⁺ across the guard cell membrane, leading to stomatal closure. Here we show that the expression pattern of the single M. truncatula outward Shaker channel, which has been named MtGORK, includes the root vasculature, guard cells and root hairs. As shown by patch‐clamp experiments on root hair protoplasts, besides the Shaker‐type slowly activating outwardly rectifying K⁺ conductance encoded by MtGORK , a second K⁺‐permeable conductance, displaying fast activation and weak rectification, can be expressed by M. truncatula . A knock‐out (KO) mutation resulting in an absence of MtGORK activity is shown to weakly reduce K⁺ translocation to shoots, and only in plants engaged in rhizobial symbiosis, but to strongly affect the control of stomatal aperture and transpirational water loss. In legumes, the early electrical signaling pathway triggered by Nod‐factor perception is known to comprise a short transient depolarization of the root hair plasma membrane. In the absence of the functional expression of MtGORK, the rate of the membrane repolarization is found to be decreased by a factor of approximately two. This defect was without any consequence on infection thread development and nodule production in plants grown in vitro , but a decrease in nodule production was observed in plants grown in soil.

中文翻译：

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紫花苜蓿中单个摇床向外K +通道的功能表征和生理作用。

豆科植物Medi藜模型具有单个向外的Shaker K ⁺通道，而拟南芥具有两个这种类型的通道，分别称为AtSKOR和AtGORK，其中AtSKOR被证明在K ⁺分泌到根的木质部汁液中起主要作用。脉管系统和AtGORK被证明介导了K ⁺穿过保卫细胞膜的流出，导致气孔关闭。在这里，我们显示了单个M. truncatula的表达模式向外摇床通道，已命名为MtGORK，包括根脉管系统，保卫细胞和根毛。如对根毛原生质体的膜片钳实验所示，除由MtGORK编码的Shaker型缓慢激活向外整流的K ⁺电导外，第二种K ⁺渗透性电导也表现出快速激活和弱整流，它可以由M. truncatula表达。。敲除（KO）突变导致缺乏MtGORK活性，显示出弱降低K ⁺易位至芽，仅在从事根瘤菌共生的植物中，但强烈影响气孔孔径的控制和蒸腾失水。在豆类中，由Nod因子感知触发的早期电信号传导途径包括根毛质膜的短暂短暂去极化。在没有MtGORK的功能性表达的情况下，发现膜复极化的速率降低了约两倍。该缺陷对体外生长的植物的感染线发育和根瘤产生没有任何影响，但是在土壤中生长的植株中观察到根瘤产生减少。