State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resource, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China.
Plant Cell Rep. 2012 Feb;31(2):379-89. doi: 10.1007/s00299-011-1173-0. Epub 2011 Oct 19.
In plants, small heat shock proteins (sHSPs) are unusually abundant and diverse proteins involved in various abiotic stresses, but their functions in seed vigor remain to be fully explored. In this study, we report the isolation and functional characterization of a sHSP gene, NnHSP17.5, from sacred lotus (Nelumbo nucifera Gaertn.) in seed germination vigor and seedling thermotolerance. Sequence alignment and phylogenetic analysis indicate that NnHSP17.5 is a cytosolic class II sHSP, which was further supported by the cytosolic localization of the NnHSP17.5-YFP fusion protein. NnHSP17.5 was specifically expressed in seeds under normal conditions, and was strongly up-regulated in germinating seeds upon heat and oxidative stresses. Transgenic Arabidopsis seeds ectopically expressing NnHSP17.5 displayed enhanced seed germination vigor and exhibited increased superoxide dismutase activity after accelerated aging treatment. In addition, improved basal thermotolerance was also observed in the transgenic seedlings. Taken together, this work highlights the importance of a plant cytosolic class II sHSP both in seed germination vigor and seedling thermotolerance.
在植物中，小分子热激蛋白（sHSPs）是一种异常丰富和多样化的蛋白质，参与各种非生物胁迫，但它们在种子活力中的功能仍有待充分探索。在这项研究中，我们从神圣莲花（Nelumbo nucifera Gaertn.）中分离并鉴定了一个小分子热激蛋白基因 NnHSP17.5，研究其在种子活力和幼苗耐热性方面的功能。序列比对和系统发育分析表明，NnHSP17.5 是一种细胞质类 II sHSP，这一结论进一步得到了 NnHSP17.5-YFP 融合蛋白的细胞质定位的支持。NnHSP17.5 在正常条件下特异性表达于种子中，并在热和氧化胁迫下的萌发种子中强烈上调表达。转 NnHSP17.5 拟南芥种子表现出增强的种子活力，并在加速老化处理后显示出超氧化物歧化酶活性的增加。此外，在转基因幼苗中也观察到基础耐热性的提高。综上所述，这项工作强调了植物细胞质类 II sHSP 在种子活力和幼苗耐热性方面的重要性。
