Molecular characterization and expression analysis of small heat shock protein 17.3 gene from Sorbus pohuashanensis (Hance) Hedl. in response to abiotic stress

Sorbus pohuashanensis, a native tree species in China that is distributed at high altitudes. However, the problem of adaptability when introducing S. pohuashanensis to low altitude areas has not been solved. sHSPs can respond and play an essential role when exposing to abiotic stresses for plants. In this study, we aimed to investigate the expression patterns underlying the abiotic stress response of the small heat shock protein 17.3 gene from S. pohuashanensis (SpHSP17.3) at growing low altitude. 1 to 4 years old seedlings of S. pohuashanensis were used as materials for the gene cloning, the tissue-specific expression and the expression analysis underlying the response to abiotic stress using the transgentic methods and qPCR. We identified the open reading frame (ORF) sequence of SpHSP17.3 of 471 bp, which encodes a 17.3 kD protein of 156 amino acids that is located in cytoplasmic. We found that SpHSP17.3 had the highest expression in the stem, followed sequentially by fruit, root, and flower. The expression level of SpHSP17.3 in the leaves was significantly induced by the high temperature (42 °C), NaCl salt and drought stress of S. pohuashanensis. Notably, the same SpHSP17.3 expression trend was detected in the SpHSP17.3-overexpressing homozygous transgenic Arabidopsis underlying the high temperature, NaCl salt and drought stress, and the SpHSP17.3-overexpressing homozygous transgenic Arabidopsis also showed higher seed germination rates under the NaCl salt stress conditions. Our results suggested that SpHSP17.3 is involved in the response to high temperature, Nacl salt, and drought stress which would play a certain effect in the adaptability of introduction and domestication of S. pohuashanensis.