Overexpression of anthocyanin regulatory transcription factors can alleviate salt stress-induced growth inhibition in torenia ‘Kauai Rose’

The role of anthocyanins in alleviating salt stress-induced plant growth inhibition has been reported in several plant species. Despite several studies on anthocyanin synthesis in torenia, the role of anthocyanins in salt stress tolerance remains unexplored. Therefore, in this study, we aimed to investigate whether anthocyanin-rich transgenic torenia ‘Kauai Rose’ lines (RS3, RS7, BM5, and BM7), which were overexpressed with anthocyanin regulatory transcription factors (TFs) (RsMYB1 or B-Peru + mPAP1), have a greater tolerance to salt stress than wild type (WT) by determining various factors associated with salt stress. Under salt stress conditions, all transgenic plants grew better than their WT counterparts, indicating greater tolerance to salt stress. This increased tolerance was associated with the presence of higher levels of enzymatic antioxidants, such as superoxidase dismutase, peroxidase, and catalase, as well as higher levels of soluble proteins and lower levels of malondialdehyde in transgenic plants. Furthermore, transgenic plants controlled stomatal opening to reduce water loss during the stress period; however, this phenomenon was not observed in WT plants during the early stress period. The results revealed that anthocyanins can alleviate salt stress-induced plant growth inhibition in torenia. Therefore, generation of anthocyanin-enriched plants through overexpression of anthocyanin regulatory TFs is an alternative approach for the development of salt stress-tolerant plants.