Overexpression of RsMYB1 enhances heavy metal stress tolerance in transgenic petunia by elevating the transcript levels of stress tolerant and antioxidant genes

Abstract

The RsMYB1 transcription factor (TF) controls the regulation of anthocyanin in radish (Raphanus sativus), and its overexpression in tobacco and petunia strongly enhances anthocyanin production. However, no data exists on whether RsMYB1 is involved in the mechanism that leads to abiotic stress tolerance. Under normal conditions, transgenic petunia plants expressing RsMYB1 and WT were able to thrive by producing well-developed broad leaves and regular roots. In contrast, a reduction in plant growth was observed when they were exposed to heavy metals (CuSO4, ZnSO4, MnSO4, and K2Cr2O7). However, RsMYB1-overexpressing plants were found to be more tolerant to the stresses than the WT plants because the expressions of stress tolerant genes (GSH and PCs) and antioxidant genes (SOD, CAT, and POX) were enhanced. In addition, according to the phylogenetic analysis, RsMYB1 has a strong sequence similarity with other MYB TFs that confer different abiotic stresses. These results suggest that overexpression of RsMYB1 enhances the expression levels of metal-induced stress tolerance genes and antioxidant genes, and the resultant increase in gene expression improves heavy metal stress tolerance in petunia.