Soybean SAT1 (Symbiotic Ammonium Transporter 1) encodes a bHLH transcription factor involved in nodule growth and NH₄⁺ transport
Date
2014
Authors
Chiasson, D.
Loughlin, P.
Mazurkiewicz, D.
Mohammadidehcheshmeh, M.
Fedorova, E.
Okamoto, M.
McLean, E.
Glass, A.
Smith, S.
Bisseling, T.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Journal article
Citation
Proceedings of the National Academy of Sciences of the United States of America, 2014; 111(13):4814-4819
Statement of Responsibility
David M. Chiasson, Patrick C. Loughlin, Danielle Mazurkiewicz, Manijeh Mohammadidehcheshmeh, Elena E. Fedorova, Mamoru Okamoto, Elizabeth McLean, Anthony D. M. Glass, Sally E. Smith, Ton Bisseling, Stephen D. Tyerman, David A. Day, and Brent N. Kaiser
Conference Name
Abstract
Glycine max symbiotic ammonium transporter 1 was first documented as a putative ammonium (NH4(+)) channel localized to the symbiosome membrane of soybean root nodules. We show that Glycine max symbiotic ammonium transporter 1 is actually a membrane-localized basic helix-loop-helix (bHLH) DNA-binding transcription factor now renamed Glycine max bHLH membrane 1 (GmbHLHm1). In yeast, GmbHLHm1 enters the nucleus and transcriptionally activates a unique plasma membrane NH4(+) channel Saccharomyces cerevisiae ammonium facilitator 1. Ammonium facilitator 1 homologs are present in soybean and other plant species, where they often share chromosomal microsynteny with bHLHm1 loci. GmbHLHm1 is important to the soybean rhizobium symbiosis because loss of activity results in a reduction of nodule fitness and growth. Transcriptional changes in nodules highlight downstream signaling pathways involving circadian clock regulation, nutrient transport, hormone signaling, and cell wall modification. Collectively, these results show that GmbHLHm1 influences nodule development and activity and is linked to a novel mechanism for NH4(+) transport common to both yeast and plants.