State Key Laboratory of Plant Environmental Resilience, Engineering Research Center of Plant Growth Regulator, Ministry of Education & College of Agronomy and Biotechnology, China Agricultural University, No.2 Yuanmingyuan Xilu, Haidian District, Beijing, 100193, China.
Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518000, China.
New Phytol. 2024 Mar;241(5):2090-2107. doi: 10.1111/nph.19500. Epub 2024 Jan 2.
High-affinity K (HAK) transporters play essential roles in facilitating root K uptake in higher plants. Our previous studies revealed that GhHAK5a, a member of the HAK family, is crucial for K uptake in upland cotton. Nevertheless, the precise regulatory mechanism governing the expression of GhHAK5a remains unclear. The yeast one-hybrid screening was performed to identify the transcription factors responsible for regulating GhHAK5a, and ethylene response factor 9 (GhERF9) was identified as a potential candidate. Subsequent dual-luciferase and electrophoretic mobility shift assays confirmed that GhERF9 binds directly to the GhHAK5a promoter, thereby activating its expression. Silencing of GhERF9 decreased the expression of GhHAK5a and exacerbated K deficiency symptoms in leaves, also decreased K uptake rate and K content in roots. Additionally, it was observed that the application of ethephon (an ethylene-releasing reagent) resulted in a significant upregulation of GhERF9 and GhHAK5a, accompanied by an increased rate of K uptake. Expectedly, GhEIN3b and GhEIL3c, the two key components involved in ethylene signaling, bind directly to the GhERF9 promoter. These findings provide valuable insights into the molecular mechanisms underlying the expression of GhHAK5a and ethylene-mediated K uptake and suggest a potential strategy to genetically enhance cotton K uptake by exploiting the EIN3/EILs-ERF9-HAK5 module.
高亲和钾（HAK）转运体在促进高等植物根系钾吸收中发挥重要作用。我们之前的研究表明，HAK 家族的一员 GhHAK5a 对陆地棉的钾吸收至关重要。然而，调控 GhHAK5a 表达的确切调节机制尚不清楚。进行了酵母单杂交筛选，以鉴定负责调控 GhHAK5a 的转录因子，乙烯响应因子 9（GhERF9）被鉴定为一个潜在的候选因子。随后的双荧光素酶和电泳迁移率变动分析证实，GhERF9 直接结合到 GhHAK5a 启动子上，从而激活其表达。GhERF9 的沉默降低了 GhHAK5a 的表达，并加剧了叶片中的钾缺乏症状，还降低了根中的钾吸收速率和钾含量。此外，观察到乙烯释放剂乙膦处理导致 GhERF9 和 GhHAK5a 的显著上调，同时钾吸收速率增加。可以预期的是，乙烯信号转导中涉及的两个关键组分 GhEIN3b 和 GhEIL3c 直接结合到 GhERF9 启动子上。这些发现为 GhHAK5a 的表达和乙烯介导的钾吸收的分子机制提供了有价值的见解，并提出了一种通过利用 EIN3/EILs-ERF9-HAK5 模块遗传增强棉花钾吸收的潜在策略。
