TY - JOUR
T1 - Cross talk between gibberellin and cytokinin
T2 - The Arabidopsis GA response inhibitor SPINDLY plays a positive role in cytokinin signaling
AU - Greenboim-Wainberg, Yaarit
AU - Maymon, Inbar
AU - Borochov, Roy
AU - Alvarez, John
AU - Olszewski, Neil
AU - Ori, Naomi
AU - Eshed, Yuval
AU - Weiss, David
PY - 2005
Y1 - 2005
N2 - SPINDLY (SPY) is a negative regulator of gibberellin (GA) responses; however, spy mutants exhibit various phenotypic alterations not found in GA-treated plants. Assaying for additional roles for SPY revealed that spy mutants are resistant to exogenously applied cytokinin. GA also repressed the effects of cytokinin, suggesting that there is cross talk between the two hormone-response pathways, which may involve SPY function. Two spy alleles showing severe (spy-4) and mild (spy-3) GA-associated phenotypes exhibited similar resistance to cytokinin, suggesting that SPY enhances cytokinin responses and inhibits GA signaling through distinct mechanisms. GA and spy repressed numerous cytokinin responses, from seedling development to senescence, indicating that cross talk occurs early in the cytokinin-signaling pathway. Because GA3 and spy-4 inhibited induction of the cytokinin primary-response gene, type-A Arabidopsis response regulator 5, SPY may interact with and modify elements from the phosphorelay cascade of the cytokinin signal transduction pathway. Cytokinin, on the other hand, had no effect on GA biosynthesis or responses. Our results demonstrate that SPY acts as both a repressor of GA responses and a positive regulator of cytokinin signaling. Hence, SPY may play a central role in the regulation of GA/cytokinin cross talk during plant development.
AB - SPINDLY (SPY) is a negative regulator of gibberellin (GA) responses; however, spy mutants exhibit various phenotypic alterations not found in GA-treated plants. Assaying for additional roles for SPY revealed that spy mutants are resistant to exogenously applied cytokinin. GA also repressed the effects of cytokinin, suggesting that there is cross talk between the two hormone-response pathways, which may involve SPY function. Two spy alleles showing severe (spy-4) and mild (spy-3) GA-associated phenotypes exhibited similar resistance to cytokinin, suggesting that SPY enhances cytokinin responses and inhibits GA signaling through distinct mechanisms. GA and spy repressed numerous cytokinin responses, from seedling development to senescence, indicating that cross talk occurs early in the cytokinin-signaling pathway. Because GA3 and spy-4 inhibited induction of the cytokinin primary-response gene, type-A Arabidopsis response regulator 5, SPY may interact with and modify elements from the phosphorelay cascade of the cytokinin signal transduction pathway. Cytokinin, on the other hand, had no effect on GA biosynthesis or responses. Our results demonstrate that SPY acts as both a repressor of GA responses and a positive regulator of cytokinin signaling. Hence, SPY may play a central role in the regulation of GA/cytokinin cross talk during plant development.
UR - http://www.scopus.com/inward/record.url?scp=22544468704&partnerID=8YFLogxK
U2 - 10.1105/tpc.104.028472
DO - 10.1105/tpc.104.028472
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C2 - 15608330
AN - SCOPUS:22544468704
SN - 1040-4651
VL - 17
SP - 92
EP - 102
JO - Plant Cell
JF - Plant Cell
IS - 1
ER -