Overexpression of a <i>Triticum aestivum</i> Calreticulin gene (<i>TaCRT1</i>) Improves Salinity Tolerance in Tobacco

<div><p>Calreticulin (CRT) is a highly conserved and abundant multifunctional protein that is encoded by a small gene family and is often associated with abiotic/biotic stress responses in plants. However, the roles played by this protein in salt stress responses in wheat (<i>Triticum aestivum</i>) remain obscure. In this study, three <i>TaCRT</i> genes were identified in wheat and named <i>TaCRT1</i>, <i>TaCRT</i>2 and <i>TaCRT3-1</i> based on their sequence characteristics and their high homology to other known <i>CRT</i> genes. Quantitative real-time PCR expression data revealed that these three genes exhibit different expression patterns in different tissues and are strongly induced under salt stress in wheat. The calcium-binding properties of the purified recombinant <i>TaCRT1</i> protein were determined using a PIPES/Arsenazo III analysis. <i>TaCRT1</i> gene overexpression in <i>Nicotiana tabacum</i> decreased salt stress damage in transgenic tobacco plants. Physiological measurements indicated that transgenic tobacco plants showed higher activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) than non-transgenic tobacco under normal growth conditions. Interestingly, overexpression of the entire <i>TaCRT1</i> gene or of partial <i>TaCRT1</i> segments resulted in significantly higher tolerance to salt stress in transgenic plants compared with their WT counterparts, thus revealing the essential role of the C-domain of <i>TaCRT1</i> in countering salt stress in plants.</p>