Enhancing Cadmium Stress Tolerance in Potato Plants Through Overexpression of the VvWRKY2 Transcription Factor

WRKY transcription factors (TF) are identified as important regulating plant proteins involved in stress response signaling pathways. Overexpression of these transcription factors in plants improved plant biotic and abiotic stress responses. In this context, we have envisaged transferring a cDNA encoding the grapevine VvWRKY2TF in potato plants. Four transgenic lines were selected (BFW2A, BFW2C, BFW2D, and BFW2F). In the present study, their response to Cadmium (Cd) stress (50, 100, 150, and 300 μM) was evaluated in vitro. Cadmium is recognized as being among the most harmful heavy metals to plants. Its accumulation in plant cells and tissues disturbs cell homeostasis and causes numerous metabolic damages that affect productivity. The wildtype (WT) plants from the BF15 potato variety and the transgenic plants overexpressing VvWRKY2TF were submitted to cadmium in vitro stress for 20 days. Plant growth and oxidative stress parameters were followed in these plants. All transgenic plants appeared more vigorous than WT. The BFW2A, BFW2C, and BFW2D lines showed better stem development rates than the WT and BFW2F lines. Malondialdehyde (MDA) production in both roots and leaves was reduced in BFW2A, BFW2C, and BFW2D plants as compared to BFW2F and WT plants. This result was associated with the best antioxidant activities of superoxide dismutase (SOD) and catalase (CAT) displayed by these genetically modified lines suggesting their better adaptation to Cd stress conditions. Cd accumulation in plant tissues was investigated, and higher levels of Cd were found in transgenic plants than in WT plants. These findings point to a functional Cd sequestration mechanism in the roots of transgenic plants expressing VvWRKY2. These findings imply that the VvWRKY2 TF is implicated in heavy metal response signaling processes. Its overexpression in plants may be an efficient strategy to reduce the negative effects of Cd stress, promoting the growth patterns and the activity of reactive oxygen species-scavenging enzymes in potato plants.

Graphical Abstract