Repression of Nitrogen Starvation Responses by Members of the Arabidopsis GARP-Type Transcription Factor NIGT1/HRS1 Subfamily

• Published in: The Plant cell Vol. 30; no. 4; pp. 925 - 945
• Main Authors: Kiba, Takatoshi, Inaba, Jun, Kudo, Toru, Ueda, Nanae, Konishi, Mineko, Mitsuda, Nobutaka, Takiguchi, Yuko, Kondou, Youichi, Yoshizumi, Takeshi, Ohme-Takagi, Masaru, Matsui, Minami, Yano, Kentaro, Yanagisawa, Shuichi, Sakakibara, Hitoshi
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01.04.2018
• Subjects: Availability; Deregulation; Gene expression; Genes; Genomes; Molecular chains; Molecular modelling; Nitrogen; Nutrient availability; Optimization; Plant growth; Proteins; Recycling; Regulators; Repressors; Target recognition; Transcription factors; Variation
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.17.00810

Nitrogen (N) is often a limiting nutrient whose availability determines plant growth and productivity. Because its availability is often low and/or not uniform over time and space in nature, plants respond to variations in N availability by altering uptake and recycling mechanisms, but the molecular mechanisms underlying how these responses are regulated are poorly understood. Here, we show that a group of GARP G2-like transcription factors, Arabidopsis thaliana NITRATE-INDUCIBLE, GARP-TYPE TRANSCRIPTIONAL REPRESSOR1/HYPERSENSITIVE TO LOW Pi-ELICITED PRIMARY ROOT SHORTENING1 proteins (NIGT1/HRS1s), are factors that bind to the promoter of the N starvation marker NRT2.4 and repress an array of N starvation-responsive genes under conditions of high N availability. Transient assays and expression analysis demonstrated that NIGT1/HRS1s are transcriptional repressors whose expression is regulated by N availability. We identified target genes of the NIGT1/HRS1s by genome-wide transcriptome analyses and found that they are significantly enriched in N starvation response-related genes, including N acquisition, recycling, remobilization, and signaling genes. Loss of NIGT1/HRS1s resulted in deregulation of N acquisition and accumulation. We propose that NIGT1/HRS1s are major regulators of N starvation responses that play an important role in optimizing N acquisition and utilization under fluctuating N conditions.