Inducing Expression of the BAS1 Gene via the SAG12 Promoter to Delay Flower and Plant Senescence in Transgenic Petunia hybrida

Background: Brassinosteroids (BRs) are essential hormones that play crucial roles in plant growth, reproduction and response to abiotic and biotic stress. Results: In transgenic Petunia hybrida , resulting in short stature, dark green leaves, and slowed aging.We demonstrate that the exogenous expression of the SAG12-BAS1 gene results in delayed senescence of flowers. SAG12-BAS1 transgenic lines, grown in the vegetative state, exhibited a range of phenotypic changes, including dark green leaves, short stature, delayed senescence, increased flower bud counts, branching, reduced internode lengths, and delayed flowering. SAG12-BAS1 transgenic expression increased the activity of protective enzymes, reduced malondialdehyde content, and increased chlorophyll content and soluble sugar accumulation in plants. Expression of senescence genes was increased in the transgenic Petunia hybrida compared to wild-type plants. Conclusions: Our finding suggests that BAS1 could be used as a potential candidate gene regulate plant flower senescence and prolong flower longevity.

Cloning and Functional Verification of Genes Related to 2-Phenylethanol Biosynthesis in Rosa rugosa

In China, Rosa rugosa is cultivated as a source of natural perfumes. Rose essential oil is known as “liquid gold”, given its high economic and health value. 2-phenylethanol accounts for more than 10% of the total mass fraction of the essential oil derived from R. rugosa. The regulatory mechanisms underlying 2-phenylethanol metabolism in R. rugosa, however, remain unclear. In this study, RrAAAT and RrPPDC1, two genes related to 2-phenylethanol synthesis, were cloned from R. rugosa. Expression analysis revealed that RrAAAT and RrPPDC1 were highly expressed in rose flowers in the full opening and withering stages, and in calyxes. The overexpression vectors of RrAADC, RrAAAT, and RrPPDC1 were established and transformed into Petunia hybrida via Agrobacterium-mediated genetic transformation. Results demonstrated that the overexpression of RrAADC and RrAAAT increased the 2-phenylethanol content of transgenic petunia flowers. The results of this study provide a basis for the introduction of genes related to 2-phenylethanol synthesis into roses to increase the 2-phenylethanol content of rose essential oil.

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

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.