SPINDLY, a negative regulator of gibberellic acid signaling, is involved in the plant abiotic stress response.
The SPINDLY (SPY) gene was first identified as a negative regulator of plant gibberellic acid (GA) signaling because mutation of this gene phenocopies plants treated with an overdose of bioactive GA and results in insensitivity to a GA inhibitor during seed germination. The SPY gene encodes an O-linked N-acetylglucosamine transferase that can modify the target protein and modulate the protein activity in cells. In this study, we describe the strong salt and drought tolerance phenotypes of Arabidopsis (Arabidopsis thaliana) spy-1 and spy-3 mutants in addition to their GA-related phenotypes. SPY gene expression was found to be drought stress inducible and slightly responsive to salt stress. Transcriptome analysis of spy-3 revealed that many GA-responsive genes were up-regulated, which could explain the GA-overdosed phenotype of spy-3. Some stress-inducible genes were found to be up-regulated in spy-3, such as genes encoding late embryogenesis abundant proteins, Responsive to Dehydration20, and AREB1-like transcription factor, which may confer stress tolerance on spy-3. CKX3, a cytokinin (CK) catabolism gene, was up-regulated in spy-3; this up-regulation indicates that the mutant possesses reduced CK signaling, which is consistent with a positive role for SPY in CK signaling. Moreover, overexpression of SPY in transgenics (SPY overexpressing [SPY-OX]) impaired plant drought stress tolerance, opposite to the phenotype of spy. The expression levels of several genes, such as DREB1E/DDF1 and SNH1/WIN1, were decreased in SPY-OX but increased in spy-3. Taken together, these data indicate that SPY plays a negative role in plant abiotic stress tolerance, probably by integrating environmental stress signals via GA and CK cross talk.
Biological Resources and Post-Harvest Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki 305-8686, Japan.
Feng
F
Qin
Ken-Suke
KS
Kodaira
Kyonoshin
K
Maruyama
Junya
J
Mizoi
Lam-Son Phan
LS
Tran
Yasunari
Y
Fujita
Kyoko
K
Morimoto
Kazuo
K
Shinozaki
Kazuko
K
Yamaguchi-Shinozaki
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism; D003681:Dehydration; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D005875:Gibberellins / Q000378:metabolism*; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism*; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D018749:RNA, Plant / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D055049:Salt Tolerance; D036226:Seedlings / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome; D015854:Up-Regulation
D029681:Arabidopsis Proteins; D003583:Cytokinins; D005875:Gibberellins; D010937:Plant Growth Regulators; D018749:RNA, Plant; D012097:Repressor Proteins; C101465:SPY protein, Arabidopsis; D014157:Transcription Factors; C007842:gibberellic acid