Cross talk between gibberellin and cytokinin: The Arabidopsis GA response inhibitor SPINDLY plays a positive role in cytokinin signaling
Cross talk between gibberellin and cytokinin: The Arabidopsis GA response inhibitor SPINDLY plays a positive role in cytokinin signaling
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DOI：
10.1105/tpc.104.028472
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发表时间：
2005-01-01
期刊：
影响因子：
11.6
通讯作者：
Weiss, D
中科院分区：
文献类型：
--
作者：
Greenboim-Wainberg, Y;Maymon, I;Weiss, D
Spindly(Spin)是赤霉素(GA)反应的负调控因子；然而，Spy突变体表现出在GA处理的植物中没有发现的各种表型变化。对Spy的额外作用的分析表明，Spy突变体对外源应用的细胞分裂素具有抵抗力。GA还抑制了细胞分裂素的作用，这表明这两条激素反应途径之间存在串扰，这可能涉及间谍功能。表现为严重(SPY-4)和轻度(SPY-3)GA相关表型的两个SPY等位基因对细胞分裂素的抗性相似，表明SPY通过不同的机制增强细胞分裂素反应和抑制GA信号转导。GA和SPY抑制了从幼苗发育到衰老的大量细胞分裂素反应，表明串扰发生在细胞分裂素信号通路的早期。由于GA(3)和SPY-4抑制了细胞分裂素初级反应基因A型拟南芥反应调节子5的诱导，因此SPY可能与细胞分裂素信号转导通路中的磷酸中继级联反应元件相互作用和修饰。另一方面，细胞分裂素对GA的生物合成或反应没有影响。我们的结果表明，SPY既是GA反应的抑制者，也是细胞分裂素信号的正向调节因子。因此，在植物发育过程中，SPY可能在GA/细胞分裂素串扰的调控中发挥核心作用。
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 GA(3) 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.