A WRKY Transcription Factor, TaWRKY76 , From Triticum aestivum Enhanced Resistance to Cadmium Stress in Transgenic Arabidopsis thaliana and Wheat

WRKY transcription factors are key regulators of plant signaling pathways associated with both biotic and abiotic stress responses. Here, we identified and characterized TaWRKY76. Expression of TaWRKY76 was detected across all tissues analyzed and was upregulated under cadmium (Cd) and abscisic acid (ABA) treatments. Transgenic Arabidopsis thaliana plants containing the TaWRKY76 promoter exhibited higher GUS activity following Cd stress, and the C-terminal region of TaWRKY76 was shown to play a role as a transcription activator with a particular binding affinity for the W-box region. To examine the TaWRKY76 function, Arabidopsis and wheat overexpression lines were generated and were shown to exhibit improved tolerance to Cd. The transgenic plants exhibited a superior germination rate, increased root development, and higher chlorophyll and proline contents compared to the wild-type (WT), while displaying mitigated electrolyte leakage and lower levels of malondialdehyde. Additionally, Cd stress triggered increased activity of ROS-scavenging enzymes and diminished ROS buildup in both transgenic Arabidopsis and wheat plants. Moreover, TaWRKY76 overexpression in wheat also led to upregulation of ABA-related genes compared with the WT under Cd stress. These results indicate that TaWRKY76 is essential to the Cd stress response and may be a useful target for increasing tolerance to this toxic metal in wheat.