Biological Resources and Post-Harvest Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki 305-8686, Japan.
Plant Physiol. 2011 Dec;157(4):1900-13. doi: 10.1104/pp.111.187302. Epub 2011 Oct 19.
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.
SPINDLY（SPY）基因最初被鉴定为植物赤霉素（GA）信号的负调节剂，因为该基因突变的表型类似于过量生物活性 GA 处理的植物，并且在种子萌发过程中对 GA 抑制剂不敏感。SPY 基因编码一种 O-连接的 N-乙酰葡萄糖胺转移酶，可修饰靶蛋白并调节细胞中的蛋白质活性。在这项研究中，我们描述了拟南芥（Arabidopsis thaliana）spy-1 和 spy-3 突变体除了具有 GA 相关表型之外，还具有很强的耐盐和耐旱性表型。发现 SPY 基因表达受干旱胁迫诱导，对盐胁迫略有反应。spy-3 的转录组分析显示，许多 GA 响应基因上调，这可以解释 spy-3 的 GA 过量表型。在 spy-3 中发现一些应激诱导基因上调，例如编码晚期胚胎丰富蛋白的基因、对脱水 20 响应的基因和 AREB1 样转录因子，这可能使 spy-3 具有应激耐受性。CKX3，一种细胞分裂素（CK）分解代谢基因，在 spy-3 中上调；这种上调表明突变体具有降低的 CK 信号，这与 SPY 在 CK 信号中的积极作用一致。此外，SPY 在转基因植物（SPY 过表达 [SPY-OX]）中的过表达会损害植物的干旱胁迫耐受性，与 spy 的表型相反。几个基因的表达水平，如 DREB1E/DDF1 和 SNH1/WIN1，在 SPY-OX 中降低，但在 spy-3 中增加。综上所述，这些数据表明 SPY 在植物非生物胁迫耐受性中起负调控作用，可能通过 GA 和 CK 交叉对话整合环境胁迫信号。
