New Phytol|河南大学生科院龙雨实验室揭示MYB77通过促进HAK5的表达来调控高亲和力钾的吸收

在拟南芥中，在100µM以下时，高亲和力K+转运子HAK5是根系吸收K+的主要途径;HAK5对低K+ (LK)胁迫的响应是在K+缺乏时强烈而迅速地增加表达。因此，HAK5表达的正调控因子具有提高LK下K+摄取的潜力。

在这里，我们发现MYB77的突变体具有LK诱导的叶片褪绿表型、降低K+含量和降低hak5突变体对Rb+的吸收，但并不会导致根的生长变短，而且MYB77的过表达增强了K+的吸收，提高了对LK胁迫的耐受性。

此外，我们还发现MYB77通过与HAK5启动子结合，正调控HAK5的表达，并提高根系对K+的高亲和力吸收。

因此，我们的研究结果揭示了在LK胁迫下增加HAK5表达的新途径，并为提高植物对LK的耐受性提供了一个候选途径。

In Arabidopsis, the high-affinity K+ transporter HAK5 is the major pathway for root K+ uptake when below 100 µM; HAK5 responds to Low-K+ (LK) stress by strongly and rapidly increasing its expression during K+-deficiency. Therefore, positive regulators of HAK5 expression have the potential to improve K+ uptake under LK.

Here, we show that mutants of the transcription factor MYB77 share a LK-induced leaf chlorosis phenotype, lower K+ content, and lower Rb+ uptake of the hak5 mutant, but not the shorter root growth, and that overexpression of MYB77 enhanced K+ uptake and improved tolerance to LK stress.

Furthermore, we demonstrated that MYB77 positively regulates the expression of HAK5, by binding to the HAK5 promoter and enhances high-affinity K+ uptake of roots.

As such, our results reveal a novel pathway for enhancing HAK5 expression under LK stress, and provides a candidate for increasing the tolerance of plants to LK.

https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.17589?af=R

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