Expression of a bacterial endo beta-1,3-glucanase gene under the control of CAMV 35S promoter in Nicotiana plumbaguinifolia protoplasts.

A gene which codes for a thermostable endo beta-1,3-glucanase (EC 3.2.1.39) from a Gram positive anaerobic thermophilic bacteria Clostridium thermocellum F7, was fused to 35S promoter and polyadenylation signal of Cauliflower Mosaic Virus (CaMV) strain Cabb B-D. This chimaeric gene fusion was introduced into Nicotiana plumbaguinifolia protoplasts using PEG-mediated DNA transfer method of transformation. Transient expression of the thermostable endo beta-1,3-glucanase was carried out in the protoplasts and was assayed at 70 degrees C pH 8.0, suggesting that the chimaeric gene fusion: (i) is correctly transcribed and translated in plant cells; (ii) the product of translation (the thermostable endo beta-1,3-glucanase protein) is easy to assay since most of the plants' enzymes have their optimal reaction temperature at 40-60 degrees C and at neutral or weak-acidic condition which is a characteristic of plant cells; (iii) can be used as a model for studying and understanding some of the mechanisms of plant defence systems at the enzyme protein level, in case of stress conditions.