A Brake For Nitrogen Starvation Responses

Kiba et al. focus on transcriptional regulation of nitrogen starvation responses. Plant Cell https://doi.org/10.1105/tpc.17.00810

By Takatoshi Kiba

Background: Nitrogen availability in the soil profoundly affects plant growth and productivity, and thus crop yield. To meet expanding food demands, the global use of nitrogen fertilizer in agricultural production has increased dramatically since the 1950s and the trend is still continuing. However, much of the applied nitrogen fertilizer is not effectively used by plants. Most of the remainder is lost from the agro-ecosystem causing economic and ecological problems. Improving nitrogen fertilization methodologies is therefore extremely important but getting nitrogen fertilization rates right depends on a much better understanding of how plants regulate uptake and utilization efficiency.

Question: It is well known that plants are capable of elaborate responses to take up and use nitrogen efficiently under nitrogen-poor (or nitrogen-starved) conditions. We wanted to know how these responses are regulated at the transcription level.

Findings: We found a group of transcription factors that directly bind to the promoters of nitrogen-starvation responsive genes in Arabidopsis thaliana. We demonstrated that these transcription factors, named NIGT1/HRS1s, act as repressors of an array of nitrogen-starvation responsive genes to stop nitrogen-starvation responses when there is sufficient nitrogen. We propose that NIGT1/HRS1s are major brake of nitrogen-starvation responses that play an important role in optimizing nitrogen acquisition and utilization under fluctuating nitrogen availability and demand.

Next steps: We are interested to know whether this braking mechanism is conserved among other plants, especially among crops, and test whether it can be exploited for improvement of nitrogen uptake and utilization efficiency of crops.

Takatoshi Kiba, Jun Inaba, Toru Kudo, Nanae Ueda, Mineko Konishi, Nobutaka Mitsuda, Yuko Takiguchi, Youichi Kondou, Takeshi Yoshizumi, Masaru Ohme-Takagi, Minami Matsui, Kentaro Yano, Shuichi Yanagisawa, Hitoshi Sakakibara (2018). Repression of nitrogen-starvation responses by Arabidopsis GARP-type transcription factor AtNIGT1/HRS1 subfamily members. Plant Cell Apr 2018, 30: 925-945;  https://doi.org/10.1105/tpc.17.00810

Keywords: Nitrogen nutrient, nitrogen starvation, transcription factor