Overexpression of acdS in petunia improved tolerance to copper stress by reducing ethylene production and metal accumulation

We overexpressed the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase gene (acdS), which encodes the enzyme responsible for the degradation of an ethylene precursor (ACC), in Petunia hybrida cv. Mirage Rose. We investigated whether acdS overexpression rendered the petunia more tolerant to copper (Cu) stress. The transgenic plants exhibited greater tolerance to Cu stress than wild type (WT) plants, as evidenced by better plant growth and physiological performances. Additionally, the transgenic plants displayed significantly suppressed ethylene production and related genes, elevated expression of antioxidant and proline activity-related genes, reduced accumulation of reactive oxygen species and Cu, and increased expression of genes regulating heavy metal when compared to the WT plants. These findings elucidate the mechanism by which acdS imparts Cu stress tolerance, suggesting that overexpressing acdS in plants can facilitate their resilience to Cu stress.