By screening an expressed sequence tag (EST) library of Salvia miltiorrhiza, we detected an acidic protein, SmGRP1, with no significant similarities to the other sequences in public databases. SmGRP1 encodes a peptide of 151 amino acids, 33.77 % of which are glutamic acid residues, and the peptide was positive according to "stains-all" staining. Expression analysis revealed that SmGRP1 was expressed in all examined tissues of S. miltiorrhiza but was most highly expressed in the leaves and stems. Without a signal peptide, SmGRP1 localized to the cytoplasm in protoplasts in subcellular localization experiments. SmGRP1 expression was prominently enhanced by ABA and darkness treatments; the protein could also be induced by high temperature, NaCl, and dehydration treatments, while low temperature suppressed its expression. Furthermore, although there were no obvious phenotypic differences in SmGRP1 overexpression and SmGRP1 knockdown mutants compared with control plants under normal culture conditions, the stomata of the knockdown lines remained open when treated with ABA, darkness, NO, and H2O2. In addition, the water loss rate of the knockdown mutants was faster than that of the control lines and overexpression mutants when exposed to air. These observations indicate that SmGRP1 is a novel acidic protein with potential calcium-binding capability and is involved in stomatal movement and stress resistance.

中文翻译：

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胞质蛋白 GRP1 促进丹参中脱落酸和黑暗诱导的气孔关闭

通过筛选丹参的表达序列标签 (EST) 文库，我们检测到一种酸性蛋白 SmGRP1，与公共数据库中的其他序列没有显着相似性。SmGRP1 编码 151 个氨基酸的肽，其中 33.77% 是谷氨酸残基，根据“stains-all”染色，该肽呈阳性。表达分析表明，SmGRP1 在丹参的所有组织中均有表达，但在叶和茎中表达最高。在没有信号肽的情况下，SmGRP1 在亚细胞定位实验中定位于原生质体的细胞质。ABA和黑暗处理显着增强了SmGRP1的表达；高温、NaCl和脱水处理也可以诱导该蛋白质，而低温抑制其表达。此外，尽管与正常培养条件下的对照植物相比，SmGRP1 过表达和 SmGRP1 敲低突变体没有明显的表型差异，但在用 ABA、黑暗、NO 和 H2O2 处理时，敲低株系的气孔保持开放。此外，当暴露于空气时，敲低突变体的失水率比对照系和过表达突变体的失水速度更快。这些观察结果表明 SmGRP1 是一种新型酸性蛋白，具有潜在的钙结合能力，参与气孔运动和抗逆性。当暴露于空气时，敲低突变体的失水率比对照系和过表达突变体快。这些观察结果表明 SmGRP1 是一种新型酸性蛋白，具有潜在的钙结合能力，参与气孔运动和抗逆性。当暴露于空气时，敲低突变体的失水率比对照系和过表达突变体快。这些观察结果表明 SmGRP1 是一种新型酸性蛋白，具有潜在的钙结合能力，参与气孔运动和抗逆性。