A Heat Shock-Switchable Gene Expression System

The expression of β-D-glueuronidase (Gus) gene under the control of soybean heat shock protein(HSP) promoter Gmhsp17. 5-C was investigated in transgenic Nicotiana plumbaginifolia plants after heatshock treatment. Results of histochemical stain assay showed that the Gus activity increased markedly duringthe recovery phase (21℃) after heat shock treatment at 42℃ for 2 h. Results of quantitative fluorometric as-says indicated that maximal Gus activity after heat shock treatment could reach 5 - 6 times higher than that be-fore heat shock treatment in transgenic lines HG6 and HG9. Based on several advantages of the heat shock pro-moter such as easy to induce, sensitivity to heat shock and high inductive activity, it can be potentially used tocontrol expression of gene of interest in transgenic plants.