Elicitation of peroxidase activity in genetically transformed root cultures of Beta vulgaris L.

Abstract

Genetically transformed roots of red beet produce copious levels of peroxidase (POD) - a multifunctional enzyme with a number of commercial applications. In an effort to elicit the POD activity, the cultures were treated with biotic elicitors such as dry cell powders of microbial cultures (0.1-0.5% w/v) and the respective culture filtrates (1-5% v/v). Similarly, abiotic elicitors, particularly metal ions (2-8 folds of that present in the nutrient medium), the plant hormone Thidiazuron (at 0.25-1 ppm) and other bio-molecules such as Glutathione (at 0.5-10 mM) and Methyl jasmonate (at 20-100 µM) were used. It was observed that dry cell powder of Candida versatilis significantly elicited the enzyme activity (3.52-fold higher than the control) followed by glutathione (3.44-fold) and Rhizophus oligosporus (3.09-fold) . Among abiotic elicitors, thidiazuron, Mg and Ca salts elicited 2.49, 3.03 and 2.8 fold activities respectively. While most of the biotic elicitors were effective when added on 15 th day of culture, the abiotic elicitors were effective when added on 20 th day. Combination of highly effective elicitors indicated that glutathione (1 mM) and dry cell powder of R. oligosporus caused a 4-fold enhancement in enzyme activity, accounting for 10.9 x 10 6 U L -1 . The present study is the first report on red beet hairy roots where a large number of elicitors have been systematically screened and their probable involvements in eliciting POD activities have been discussed.