Tamyc8 Regulates Taerf6 and Inhibits Ethylene Synthesis to Confer Cd Tolerance in Wheat

Cadmium (Cd) is a toxic, non-essential heavy metal; its accumulation in plants alters metabolism and limits productivity. Though various studies have addressed Cd stress response in various species, the detailed molecular mechanisms remain unknown. Therefore, the present work investigated the influence of the TaMYC8 transcription factor (TF) on Cd-induced stress response in wheat. The present study found that TaMYC8 is a nuclear protein highly induced in the roots under Cd stress. Overexpression of TaMYC8 in the wheat cultivar ‘Bobwhite’ increased sensitivity to Cd stress, probably due to the increased levels of superoxide (O 2 .- ), malonaldehyde (MDA), jasmonic acid (JA), and Cd content, and reduced proline content and antioxidant enzyme activity. In contrast, silencing TaMYC8 via RNA interference significantly lowered Cd accumulation and improved Cd tolerance. Further analysis revealed that TaMYC8 activated TaERF6 transcription. More importantly, knockdown of TaMYC8 by RNA interference inhibited the activities of 1-aminocyclopropane-1-carboxylic (ACC) acid synthase (ACS) and ACC oxidase (ACO) of the ethylene biosynthetic pathway. The study concludes that TaMYC8 promotes TaERF6 transcription and affects the ethylene biosynthetic pathway. These findings provide a theoretical basis for breeding low Cd-accumulating wheat cultivars