HvAKT2 and HvHAK1 confer drought tolerance in barley through enhanced leaf mesophyll H+ homoeostasis
HvAKT2 and HvHAK1 confer drought tolerance in barley through enhanced leaf mesophyll H+ homoeostasis
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DOI：
10.1111/pbi.13332
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发表时间：
2020-01-24
影响因子：
13.8
通讯作者：
Wu, Feibo
中科院分区：
文献类型：
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作者：
Feng, Xue;Liu, Wenxing;Wu, Feibo
植物K+吸收主要包括由ShakerK+通道（AKT/KAT/KC）介导的低亲和力吸收机制和由HAK/KUP/KT转运蛋白调控的高亲和力吸收机制。然而，这两种K+吸收机制的耐旱性的进化和遗传作用还没有充分探讨适应旱地农业的作物。本文采用进化生物信息学、生物技术和电生理学方法，研究了两种重要的K+转运蛋白HvAKT 2和HvHAK 1在大麦耐旱性中的作用。利用大麦条纹花叶病毒诱导的耐旱野生大麦XZ 5基因沉默（BSMV-VIGS）和农杆菌介导的大麦品种Golden Promise基因转移技术，克隆了HvAKT 2和HvHAK 1基因，并对其功能进行了分析。AKT 2和HAK 1的K+选择性过滤器的特征都在来自链藻的同源物中发现，并且它们在链藻和陆地植物中进化上保守。HvAKT 2和HvHAK 1都定位于质膜，并且相对于其他测试的阳离子对K+和Rb+具有高选择性。HvAKT 2和HvHAK 1的过表达增强了转基因株系的K+吸收和H+体内平衡，从而导致这些转基因株系的耐旱性。此外，HvAKT 2-和HvHAK 1-过表达线表现出不同的响应K+，H+和Ca 2+通量跨质膜和生产的一氧化氮和过氧化氢的叶片相比，野生型和沉默线。高亲和力和低亲和力K+吸收机制及其与H+体内平衡的协调作用在野生大麦的干旱适应中起着重要作用。这些发现可能有助于未来在不断变化的全球气候中培育具有弹性的谷类作物。
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.