Plant K⁺ uptake typically consists low—affinity mechanisms mediated by Shaker K⁺ channels (AKT/KAT/KC) and high‐affinity mechanisms regulated by HAK/KUP/KT transporters, which are extensively studied. However, the evolutionary and genetic roles of both K⁺ uptake mechanisms for drought tolerance are not fully explored in crops adapted to dryland agriculture. Here, we employed evolutionary bioinformatics, biotechnological and electrophysiological approaches to determine the role of two important K⁺ transporters HvAKT2 and HvHAK1 in drought tolerance in barley. HvAKT2 and HvHAK1 were cloned and functionally characterized using barley stripe mosaic virus‐induced gene silencing (BSMV‐VIGS) in drought‐tolerant wild barley XZ5 and agrobacterium‐mediated gene transfer in the barley cultivar Golden Promise. The hallmarks of the K⁺ selective filters of AKT2 and HAK1 are both found in homologues from strepotophyte algae, and they are evolutionarily conserved in strepotophyte algae and land plants. HvAKT2 and HvHAK1 are both localized to the plasma membrane and have high selectivity to K⁺ and Rb⁺ over other tested cations. Overexpression of HvAKT2 and HvHAK1 enhanced K⁺ uptake and H⁺ homoeostasis leading to drought tolerance in these transgenic lines. Moreover, HvAKT2‐ and HvHAK1‐ overexpressing lines showed distinct response of K⁺, H⁺ and Ca²⁺ fluxes across plasma membrane and production of nitric oxide and hydrogen peroxide in leaves as compared to the wild type and silenced lines. High‐ and low‐affinity K⁺ uptake mechanisms and their coordination with H⁺ homoeostasis play essential roles in drought adaptation of wild barley. These findings can potentially facilitate future breeding programs for resilient cereal crops in a changing global climate.

中文翻译：

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HvAKT2和HvHAK1通过增强叶片的叶肉H +同质性赋予大麦耐旱性。

植物K ^+的吸收通常包括由摇床K ⁺通道（AKT / KAT / KC）介导的低亲和力机制和受HAK / KUP / KT转运蛋白调控的高亲和力机制，对此进行了广泛的研究。然而，无论是K的进化和遗传的角色⁺摄取耐旱机制尚未完全农作物探索适应旱地农业。在这里，我们采用了进化生物信息学，生物技术和电生理方法来确定两个重要的K ⁺转运蛋白HvAKT2和HvHAK1在大麦的耐旱性中的作用。HvAKT2和HvHAK1在耐旱的野生大麦XZ5中使用大麦条纹花叶病毒诱导的基因沉默（BSMV-VIGS）克隆并在大麦品种Golden Promise中进行农杆菌介导的基因转移，并对其功能进行了表征。AKT2和HAK1的K ⁺选择性过滤器的特征都存在于链藻科藻类的同系物中，并且在链藻科藻类和陆地植物中在进化上是保守的。HvAKT2和HvHAK1都位于质膜上，并且对K ⁺和Rb ^+的选择性比其他测试阳离子高。HvAKT2和HvHAK1的过表达增强了K ⁺吸收和H ⁺导致这些转基因品系的耐旱性的均一性。此外，与野生型和沉默型株系相比，HvAKT2‐和HvHAK1过表达株系在整个质膜上表现出不同的K ⁺，H ⁺和Ca ²⁺通量响应以及叶片中一氧化氮和过氧化氢的产生。高亲和力和低亲和力的K ⁺吸收机制以及它们与H ⁺稳态的协调在野生大麦的干旱适应中起着重要作用。这些发现可能会在全球气候不断变化的情况下，促进将来的抗逆谷物作物育种计划。