Expression analysis of the polyphenol oxidase gene in response to signaling molecules, herbivory and wounding in antisense transgenic tobacco plants.

Key Message: We provide evidence that the expression of the gene was significantly reduced in response to wounding, MeJ and herbivory in transgenic tobacco under wound-inducible RGLP2 promoter in an anti-sense orientation.

Abstract: Polyphenol oxidase (PPO) genes play an important role in plant defense mechanisms against biotic and abiotic stresses. In the present study, a 655 bp core sequence of the potato gene was placed under the control of wound-inducible RGLP2 promoter in an anti-sense direction to evaluate its potential effects during biotic ('s infestation) and various abiotic (wounding, MeJ, ABA) stresses. Transcriptional profiling of gene by real-time PCR (qRT-PCR) in transgenic tobacco revealed a significant suppression (3.5-fold) of in response to wounding than control plants after 24 h. In response to MeJ at different concentrations (100 µM and 200 µM), the expression was greatly down-regulated by 4.7-fold after 6 h at 100 µM MeJ, and a non-significant expression was observed with ABA treatment. Moreover, significant levels of reduction (sixfolds) was found in whitefly feeding assay indicating that expression of potato in an anti-sense orientation had down-regulated the activity. This down-regulation of by wounding, MeJ and whitefly infestation clearly links the specific expression of in biotic and abiotic stresses. In the future, gene suppression in transgenic plants using anti-sense potato gene construct can be used to inhibit enzymatic browning in fruits and vegetables, e.g., potato.