Modulation of nitrate-induced phosphate response by the MYB transcription factor RLI1/HINGE1 in the nucleus.

Molecular plant 2021 Mar 01

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The coordinated utilization of nitrogen (N) and phosphorus (P) is vital for plants to maintain nutrient balance and achieve optimal growth. Previously, we revealed a mechanism by which nitrate induces genes for phosphate utilization; this mechanism depends on NRT1.1B-facilitated degradation of cytoplasmic SPX4, which in turn promotes cytoplasmic-nuclear shuttling of PHR2, the central transcription factor of phosphate signaling, and triggers the nitrate-induced phosphate response (NIPR) and N-P coordinated utilization in rice. In this study, we unveiled a fine-tuning mechanism of NIPR in the nucleus regulated by Highly Induced by Nitrate Gene 1 (HINGE1, also known as RLI1), a MYB-transcription factor closely related to PHR2. RLI1/HINGE1, which is transcriptionally activated by PHR2 under nitrate induction, can directly activate the expression of phosphate starvation-induced genes. More importantly, RLI1/HINGE1 competes with PHR2 for binding to its repressor proteins in the nucleus (SPX proteins), and consequently releases PHR2 to further enhance phosphate response. Therefore, RLI1/HINGE1 amplifies the phosphate response in the nucleus downstream of the cytoplasmic SPX4-PHR2 cascade, thereby enabling fine-tuning of N-P balance when nitrate supply is sufficient. Copyright © 2020 The Author. Published by Elsevier Inc. All rights reserved.

Citation

Zhihua Zhang, Zhao Li, Wei Wang, Zhimin Jiang, Liping Guo, Xiaohan Wang, Yangwen Qian, Xiahe Huang, Yongqiang Liu, Xiujie Liu, Yahong Qiu, Aifu Li, Yu Yan, Junpeng Xie, Shouyun Cao, Stanislav Kopriva, Legong Li, Fanjiang Kong, Baohui Liu, Yingchun Wang, Bin Hu, Chengcai Chu. Modulation of nitrate-induced phosphate response by the MYB transcription factor RLI1/HINGE1 in the nucleus. Molecular plant. 2021 Mar 01;14(3):517-529