Fiona Jamieson1, Zhe Ji1, Eric J Belfield1, Zhong Jie Ding2, Shao Jian Zheng3, Nicholas P Harberd4. 1. Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK. 2. College of Life Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China. 3. College of Life Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China. sjzheng@zju.edu.cn. 4. Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK. nicholas.harberd@plants.ox.ac.uk.
Abstract
MAIN CONCLUSION: Genetic analysis reveals a previously unknown role for ethylene signaling in regulating Arabidopsis thaliana nitrogen metabolism. Nitrogen (N) is essential for plant growth, and assimilation of soil nitrate (NO3-) and ammonium ions is an important route of N acquisition. Although N import and assimilation are subject to multiple regulatory inputs, the extent to which ethylene signaling contributes to this regulation remains poorly understood. Here, our analysis of Arabidopsis thaliana ethylene signaling mutants advances that understanding. We show that the loss of CTR1 function ctr1-1 mutation confers resistance to the toxic effects of the NO3- analogue chlorate (ClO3-), and reduces the activity of the nitrate reductase (NR) enzyme of NO3- assimilation. Our further analysis indicates that the lack of the downstream EIN2 component (conferred by novel ein2 mutations) suppresses the effect of ctr1-1, restoring ClO3- sensitivity and NR activity to normal. Collectively, our observations indicate an important role for ethylene signaling in regulating Arabidopsis thaliana NO3- metabolism. We conclude that ethylene signaling enables environmentally responsive coordination of plant growth and N metabolism.
MAIN CONCLUSION: Genetic analysis reveals a previously unknown role for ethylene signaling in regulating Arabidopsis thaliana nitrogen metabolism. Nitrogen (N) is essential for plant growth, and assimilation of soil nitrate (NO3-) and ammonium ions is an important route of N acquisition. Although N import and assimilation are subject to multiple regulatory inputs, the extent to which ethylene signaling contributes to this regulation remains poorly understood. Here, our analysis of Arabidopsis thaliana ethylene signaling mutants advances that understanding. We show that the loss of CTR1 function ctr1-1 mutation confers resistance to the toxic effects of the NO3- analogue chlorate (ClO3-), and reduces the activity of the nitrate reductase (NR) enzyme of NO3- assimilation. Our further analysis indicates that the lack of the downstream EIN2 component (conferred by novel ein2 mutations) suppresses the effect of ctr1-1, restoring ClO3- sensitivity and NR activity to normal. Collectively, our observations indicate an important role for ethylene signaling in regulating Arabidopsis thaliana NO3- metabolism. We conclude that ethylene signaling enables environmentally responsive coordination of plant growth and N metabolism.
Authors: Patrick Achard; Mourad Baghour; Andrew Chapple; Peter Hedden; Dominique Van Der Straeten; Pascal Genschik; Thomas Moritz; Nicholas P Harberd Journal: Proc Natl Acad Sci U S A Date: 2007-03-26 Impact factor: 11.205