ORIGINAL ARTICLE AtGSNOR1 function is required for multiple developmental programs in Arabidopsis Eunjung Kwon • Angela Feechan • Byung-Wook Yun • Byung-Ho Hwang • Jacqueline A. Pallas • Jeong-Gu Kang • Gary J. Loake Received: 22 March 2012 / Accepted: 18 June 2012 / Published online: 6 July 2012 Ó Springer-Verlag 2012 Abstract Nitric oxide (NO) has been proposed to regu- late a diverse array of activities during plant growth, development and immune function. S-nitrosylation, the addition of an NO moiety to a reactive cysteine thiol, to form an S-nitrosothiol (SNO), is emerging as a prototypic redox-based post-translational modification. An ARABID- OPSIS THALIANA S-NITROSOGLUTATHIONE (GSNO) REDUCTASE (AtGSNOR1) is thought to be the major regulator of total cellular SNO levels in this plant species. Here, we report on the impact of loss- and gain-of-function mutations in AtGSNOR1 upon plant growth and develop- ment. Loss of AtGSNOR1 function in atgsnor1-3 plants increased the number of initiated higher order axillary shoots that remain active, resulting in a loss of apical dominance relative to wild type. In addition atgsnor1-3 affected leaf shape, germination, 2,4-D sensitivity and reduced hypocotyl elongation in both light and dark grown seedlings. Silique size and seed production were also decreased in atgsnor1-3 plants and the latter was reduced in atgsnor1-1 plants, which overexpress AtGSNOR1. Overexpression of AtGSNOR1 slightly delayed flowering time in both long and short days, whereas atgsnor1-3 showed early flowering compared to wild type. In the atgsnor1-3 line, FLOWERING LOCUS C(FLC) expression was reduced, whereas transcription of CONSTANS (CO) was enhanced. Therefore, AtGSNOR1 may negatively regulate the autonomous and photoperiod flowering time pathways. Both overexpression and loss of AtGSNOR1 function also reduced primary root growth, while root hair development was increased in atgsnor1-1 and reduced in atgsnor1-3 plants. Collectively, our findings imply that AtGSNOR1 controls multiple genetic networks integral to plant growth and development. Keywords Nitric oxide  S-nitrosylation  AtGSNOR1  S-nitrosothiols  Plant development Abbreviations NO Nitric oxide SNO S-nitrosothiol GSNOR1 S-nitrosoglutathione reductase FLC Flowering locus C A contribution to the Special Issue on Metabolic Plant Biology. E. Kwon  A. Feechan  B.-W. Yun  B.-H. Hwang  J.-G. Kang  G. J. Loake (&) Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, King’s Buildings, Edinburgh EH9 3JR, UK e-mail: gloake@ed.ac.uk E. Kwon e-mail: s0948811@sms.ed.ac.uk Present Address: A. Feechan CSIRO Plant Industry, PO Box 350, Glen Osmond, SA 5064, Australia Present Address: B.-W. Yun School of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Daegu 702-701, South Korea J. A. Pallas Trait Research, Syngenta, Jealott’s Hill, Bracknell, Berkshire RG42 6EY, UK Present Address: J. A. Pallas Bloomsbury Centre for Bioinformatics, University College London, Gower Street, London WC1E 6BT, UK 123 Planta (2012) 236:887–900 DOI 10.1007/s00425-012-1697-8