Characterization of 5-O-glucosyltransferase involved in anthocyanin biosynthesis in Cyclamen purpurascens

Transcriptional Changes in Damask Rose Suspension Cell Culture Revealed by RNA Sequencing

Damask roses (Rosa x damascena) are widely used in cosmetics and pharmaceutics. Here, we established an in vitro suspension cell culture for calli derived from damask rose petals. We analyzed rose suspension cell transcriptomes obtained at two different time points by RNA sequencing to reveal transcriptional changes during rose suspension cell culture. Of the 580 coding RNAs (1.3%) highly expressed in the suspension rose cells, 68 encoded cell wall-associated proteins. However, most RNAs encoded by the chloroplasts and mitochondria are not expressed. Many highly expressed coding RNAs are involved in translation, catalyzing peptide synthesis in ribosomes. Moreover, the amide metabolic process producing naturally occurring alkaloids was the most abundant metabolic process during the propagation of rose suspension cells. During rose cell propagation, coding RNAs involved in the stress response were upregulated at an early stage, while coding RNAs associated with detoxification and transmembrane transport were upregulated at the late stage. We used transcriptome analyses to reveal important biological processes and molecular mechanisms during rose suspension cell culture. Most non-coding (nc) RNAs were not expressed in the rose suspension cells, but a few ncRNAs with unknown functions were highly expressed. The expression of ncRNAs and their target coding RNAs was highly correlated. Taken together, we revealed significant biological processes and molecular mechanisms occurring during rose suspension cell culture using transcriptome analyses.

A high-quality Bougainvillea genome provides new insights into evolutionary history and pigment biosynthetic pathways in the Caryophyllales

Bougainvillea is a perennial ornamental shrub that is highly regarded in ornamental horticulture around the world. However, the absence of genome data limits our understanding of the pathways involved in bract coloration and breeding. Here, we report a chromosome-level assembly of the giga-genome of Bougainvillea × buttiana 'Mrs Butt', a cultivar thought to be the origin of many other Bougainvillea cultivars. The assembled genome is ~5 Gb with a scaffold N50 of 151 756 278 bp and contains 86 572 genes which have undergone recent whole-genome duplication. We confirmed that multiple rounds of whole-genome multiplication have occurred in the evolutionary history of the Caryophyllales, reconstructed the relationship in the Caryophyllales at whole genome level, and found discordance between species and gene trees as the result of complex introgression events. We investigated betalain and anthocyanin biosynthetic pathways and found instances of independent evolutionary innovations in the nine different Caryophyllales species. To explore the potential formation mechanism of diverse bract colors in Bougainvillea, we analyzed the genes involved in betalain and anthocyanin biosynthesis and found extremely low expression of ANS and DFR genes in all cultivars, which may limit anthocyanin biosynthesis. Our findings indicate that the expression pattern of the betalain biosynthetic pathway did not directly correlate with bract color, and a higher expression level in the betalain biosynthetic pathway is required for colored bracts. This improved understanding of the correlation between gene expression and bract color allows plant breeding outcomes to be predicted with greater certainty.

Anthocyanins Profiling Analysis and RNA-Seq Revealed the Dominating Pigments and Coloring Mechanism in Cyclamen Flowers

Pigments in cyclamen (Cyclamen purpurascens) endows flowers with great ornamental and medicinal values. However, little is known about the biosynthetic pathways of pigments, especially anthocyanins, in cyclamen flowers. Herein, anthocyanins profiling and RNA-Seq were used to decipher the molecular events using cyclamen genotypes of red (HXK) or white (BXK) flowers. We found that red cyclamen petals are rich in cyanidin-3-O-rutinoside, cyanidin-3-O-glucoside, delphinidin-3-O-glucoside, malvidin-3-O-glucoside, peonidin-3-O-rutinoside, quercetin-3-O-glucoside, and ruti. In addition, our transcriptomics data revealed 3589 up-regulated genes and 2788 down-regulated genes comparing the BXK to HXK. Our rich dataset also identified eight putative key genes for anthocyanin synthesis, including four chalcone synthase (CHS, g13809_i0, g12097_i0, g18851_i0, g36714_i0), one chalcone isomerase (CHI, g26337_i0), two flavonoid 3-hydroxylase (F3'H, g14710_i0 and g15005_i0), and one anthocyanidin synthase (ANS, g18981_i0). Importantly, we found a 2.5 order of magnitude higher expression of anthocyanin 3-O-glucosyltransferase (g8206_i0), which encodes a key gene in glycosylation of anthocyanins, in HXK compared to BXK. Taken together, our multiomics approach demonstrated massive changes in gene regulatory networks and anthocyanin metabolism in controlling cyclamen flower color.

Ph5GT silencing alters flower color and flavonoids metabolome profile in petunia

Anthocyanins are important pigments in plants and glycosylation plays an important role in the stability of anthocyanins. Anthocyanin 5-O-glucosyltransferase (5GT) can glycosylate anthocyanin at the 5-O-position. Till now, the enzymatic activity characteristics of 5GT had been studied in vitro in a variety of plants. However, the subcellular localization of 5GT protein still remained unclear, and little genetic evidence on the roles of 5GT in plants has been reported. The full-length Ph5GT gene from petunia (Petunia hybrida) was isolated in this study. Green fluorescent fusion protein assays revealed that Ph5GT protein was localized to the cytoplasm. Ph5GT was found to be highly expressed in flowers, with highest levels of expression occurring during the coloring stage of flower development. Furthermore, Ph5GT silencing led to the change in flower color from purple to light purple and a significant reduction in total anthocyanin content. The metabolome analysis revealed that the content of malvidins and petunidins modified by glycosylation at the 5-O-position was significantly reduced, while the content of their precursor without glycosylation was significantly increased, implying that Ph5GT could glycosylate malvidin and petunidin derivatives and that the substrate types of Ph5GT were expanded in comparison to previous studies.

Anthocyanins and Carotenoids Characterization in Flowers and Leaves of Cyclamen Genotypes Linked with Bioactivities Using Multivariate Analysis Techniques

The present study was carried out to evaluate and compare in vitro antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH), Trolox equivalent antioxidant capacity (TEAC), and ferric reducing antioxidant power (FRAP)), antimicrobial, anticancer activities, and the individual carotenoids and anthocyanins content of methanol extracts of the Cyclamen genotypes: Persian cyclamen accessions (Cyclamen persicum Mill.), sowbread (C. mirabile Hildebr.), and ivy-leaved cyclamen (C. hederifolium Mill.) aerial parts. The HPLC-PDA analysis revealed the presence of five individual carotenoids (i.e., neoxanthin, violaxanthin, lutein, β-carotene, and cis-β-carotene) as the main compounds in Cyclamen leaves, and the presence of seven individual anthocycanins (i.e., cyanidin 3,5-di-O-glucoside, peonidin-rutinoside, peonidin 3,5-di-O-glucoside, peonidin 3-O-glucoside, malvidin 3-O-glucoside, malvidin 3,5-di-O-glucoside, and malvidin-rutinoside) in Cyclamen flowers reported, hereby, for the first time. The highest phenolic content was found in the leaves of LC6, C. mirabile (46.32 ± 0.14 mg/g gallic acid equivalents [GAE]), and in the flowers of C. persicum Merengue Magenta (FC15) (58.63 ± 0.17 mg/g GAE), whereas the highest flavonoid content was reported in C. persicum Halios Falbala leaves, namely LC9 (54.90 ± 0.27 mg/g quercetin equivalents [QE]) and in flowers of C. persicum Victora (FC2) (77.87 ± 0.25 mg/g QE). The highest antioxidant activity in DPPH and FRAP assays was reported in C. persicum Dark Violet (LC1) and Victoria (LC2), whereas C. mirabile (LC6) had the highest activity in the TEAC assay. In flowers, high antioxidant activities in DPPH and TEAC were noticed in C. persicum Superserie Red (FC7) and Dark Violet (FC1), respectively, and Halios Falbala (FC9) exhibited the highest activity in the TEAC assay. Additionally, FC9 exhibited the highest antibacterial activity in almost all tested bacteria compared with the leaves extracts. Furthermore, the highest in vitro citotoxicity in MDA-MB-231 cells was noticed in C. hederifolium LC18 (56.71-69.35%) and FC18 (40.07-41.43%), with a lower effect against BJ cells demonstrating selective toxicity. The above findings, highlight the potential use of the Cyclamen flower and leaf extracts as significant anticancer agents along with their antioxidant and antimicrobial properties.