Ethylene-responsive element-binding factor (ERF) genes constitute one of the largest transcription factor gene families in plants. In Arabidopsis and rice, only a few ERF genes have been characterized so far. Flower senescence is associated with increased ethylene production in many flowers. However, the characterization of ERF genes in flower senescence has not been reported. In this study, 13 ERF cDNAs were cloned from petunia. Based on the sequence characterization, these PhERFs could be classified into four of the 12 known ERF families. Their predicted amino acid sequences exhibited similarities to ERFs from other plant species. Expression analyses of PhERF mRNAs were performed in corollas and gynoecia of petunia flower. The 13 PhERF genes displayed differential expression patterns and levels during natural flower senescence. Exogenous ethylene accelerates the transcription of the various PhERF genes, and silver thiosulphate (STS) decreased the transcription of several PhERF genes in corollas and gynoecia. PhERF genes of group VII showed a strong association with the rise in ethylene production in both petals and gynoecia, and might be associated particularly with flower senescence in petunia. The effect of sugar, methyl jasmonate, and the plant hormones abscisic acid, salicylic acid, and 6-benzyladenine in regulating the different PhERF transcripts was investigated. Functional nuclear localization signal analyses of two PhERF proteins (PhERF2 and PhERF3) were carried out using fluorescence microscopy. These results supported a role for petunia PhERF genes in transcriptional regulation of petunia flower senescence processes.

The global proteome and ubiquitylome were negatively correlated, and ubiquitination could be involved in the degradation of proteins during ethylene-mediated co

In plants, the shikimate pathway generally occurs in plastids and leads to the biosynthesis of aromatic amino acids. Chorismate synthase (CS) catalyses the last step of the conversion of 5-enolpyruvylshikimate 3-phosphate (EPSP) to chorismate, but the role of CS in the metabolism of higher plants has not been reported. In this study, we found that PhCS, which is encoded by a single-copy gene in petunia (Petunia hybrida), contains N-terminal plastidic transit peptides and peroxisomal targeting signals. Green fluorescent protein (GFP) fusion protein assays revealed that PhCS was localized in chloroplasts and, unexpectedly, in peroxisomes. Petunia plants with reduced PhCS activity were generated through virus-induced gene silencing and further characterized.PhCSsilencing resulted in reduced CS activity, severe growth retardation, abnormal flower and leaf development and reduced levels of folate and pigments, including chlorophylls, carotenoids and anthocyanins. A widely targeted metabolomics analysis showed that most primary and secondary metabolites were significantly changed in pTRV2-PhCS-treated corollas. Overall, the results revealed a clear connection between primary and specialized metabolism related to the shikimate pathway in petunia.