State Key Laboratory of Crop Genetics and Germplasm Enhancement, MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China.
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, Anhui 230036, China.
Plant Commun. 2020 Apr 29;1(5):100052. doi: 10.1016/j.xplc.2020.100052. eCollection 2020 Sep 14.
Plant HAK/KUP/KT family members function as plasma membrane (PM) H/K symporters and may modulate chemiosmotically-driven polar auxin transport (PAT). Here, we show that inactivation of , a rice K transporter gene, decreased rootward and shootward PAT, tiller number, and the length of both lateral roots and root hairs, while overexpression increased PAT, tiller number, and root hair length, irrespective of the K supply. Inhibitors of ATP-binding-cassette type-B transporters, NPA and BUM, abolished the -overexpression effect on PAT. The mechanistic basis of these changes included the OsHAK5-mediated decrease of transmembrane potential (depolarization), increase of extracellular pH, and increase of PM-ATPase activity. These findings highlight the dual roles of OsHAK5 in altering cellular chemiosmotic gradients (generated continuously by PM H-ATPase) and regulating ATP-dependent auxin transport. Both functions may underlie the prominent effect of OsHAK5 on rice architecture, which may be exploited in the future to increase crop yield via genetic manipulations.
植物 HAK/KUP/KT 家族成员作为质膜 (PM) H/K 同向转运体起作用，并且可能调节化学渗透驱动的极性生长素运输 (PAT)。在这里，我们表明，水稻 K 转运体基因的失活减少了根向和梢向 PAT、分蘖数以及侧根和根毛的长度，而 过表达增加了 PAT、分蘖数和根毛长度，而与 K 供应无关。ATP 结合盒型 B 转运体的抑制剂 NPA 和 BUM 消除了对 PAT 的 过表达效应。这些变化的机制基础包括 OsHAK5 介导的跨膜电位（去极化）降低、细胞外 pH 值升高和 PM-ATP 酶活性升高。这些发现强调了 OsHAK5 在改变细胞化学渗透梯度（由 PM H-ATP 酶不断产生）和调节 ATP 依赖的生长素运输方面的双重作用。这两个功能可能是 OsHAK5 对水稻结构产生显著影响的基础，未来可能通过遗传操作来提高作物产量。
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