Zhihua Zhang1, Zhao Li2, Wei Wang3, Zhimin Jiang3, Liping Guo2, Xiaohan Wang3, Yangwen Qian4, Xiahe Huang5, Yongqiang Liu6, Xiujie Liu6, Yahong Qiu6, Aifu Li6, Yu Yan6, Junpeng Xie6, Shouyun Cao3, Stanislav Kopriva7, Legong Li8, Fanjiang Kong9, Baohui Liu9, Yingchun Wang5, Bin Hu10, Chengcai Chu11. 1. State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China; School of Life Sciences, Guangzhou University, Guangzhou, China. 2. College of Plant Science, Jilin University, Changchun, China. 3. State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China. 4. Biogle Genome Editing Center, Changzhou, China. 5. State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, the Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China. 6. State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China; College of Advanced Agricultural Science, University of Chinese Academy of Sciences, Beijing, China. 7. Botanical Institute, Cluster of Excellence on Plant Sciences, University of Cologne, Cologne, Germany. 8. College of Life Sciences, Capital Normal University, Beijing, China. 9. School of Life Sciences, Guangzhou University, Guangzhou, China. 10. State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China. Electronic address: bhu@genetics.ac.cn. 11. State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, China; College of Advanced Agricultural Science, University of Chinese Academy of Sciences, Beijing, China. Electronic address: ccchu@genetics.ac.cn.
Abstract
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.
The coordinated utilization of nitrogen (N) and n>an class="Chemical">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.