Impact of AtNHX1, a vacuolar Na+/H+ antiporter, upon gene expression during short- and long-term salt stress in Arabidopsis thaliana.
BACKGROUND
AtNHX1, the most abundant vacuolar Na+/H+ antiporter in Arabidopsis thaliana, mediates the transport of Na+ and K+ into the vacuole, influencing plant development and contributing to salt tolerance. In this report, microarray expression profiles of wild type plants, a T-DNA insertion knockout mutant of AtNHX1 (nhx1), and a 'rescued' line (NHX1::nhx1) were exposed to both short (12 h and 48 h) and long (one and two weeks) durations of a non-lethal salt stress to identify key gene transcripts associated with the salt response that are influenced by AtNHX1.


RESULTS
147 transcripts showed both salt responsiveness and a significant influence of AtNHX1. Fifty-seven of these genes showed an influence of the antiporter across all salt treatments, while the remaining genes were influenced as a result of a particular duration of salt stress. Most (69%) of the genes were up-regulated in the absence of AtNHX1, with the exception of transcripts encoding proteins involved with metabolic and energy processes that were mostly down-regulated.


CONCLUSIONS
While part of the AtNHX1-influenced transcripts were unclassified, other transcripts with known or putative roles showed the importance of AtNHX1 to key cellular processes that were not necessarily limited to the salt stress response; namely calcium signaling, sulfur metabolism, cell structure and cell growth, as well as vesicular trafficking and protein processing. Only a small number of other salt-responsive membrane transporter transcripts appeared significantly influenced by AtNHX1.
Sottosanto
Jordan B
JB
Department of Plant Sciences, University of California, Davis, CA 95616, USA. jbso@ucdavis.edu
Saranga
Yehoshua
Y
Blumwald
Eduardo
E
D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D049109:Cell Proliferation; D002473:Cell Wall / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013455:Sulfur / Q000378:metabolism
D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; C117751:NHX1 protein, Arabidopsis; D012333:RNA, Messenger; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride; D013455:Sulfur