Rhamnosyltransferases involved in the biosynthesis of flavone rutinosides in Chrysanthemum species

Abstract

Linarin (acacetin-7-O-rutinoside), isorhoifolin (apigenin-7-O-rutinoside), and diosmin (diosmetin-7-O-rutinoside) are chemically and structurally similar flavone rutinoside (FR) compounds found in Chrysanthemum L. (Anthemideae, Asteraceae) plants. However, their biosynthetic pathways remain largely unknown. In this study, we cloned and compared FRs and genes encoding rhamnosyltransferases (RhaTs) among eight accessions of Chrysanthemum polyploids. We also biochemically characterized RhaTs of Chrysanthemum plants and Citrus (Citrus sinensis and Citrus maxima). RhaTs from these two genera are substrate-promiscuous enzymes catalyzing the rhamnosylation of flavones, flavanones, and flavonols. Substrate specificity analysis revealed that Chrysanthemum 1,6RhaTs preferred flavone glucosides (e.g., acacetin-7-O-glucoside), whereas Cs1,6RhaT preferred flavanone glucosides. The nonsynonymous substitutions of RhaTs found in some cytotypes of diploids resulted in the loss of catalytic function. Phylogenetic analysis and specialized pathways responsible for the biosynthesis of major flavonoids in Chrysanthemum and Citrus revealed that rhamnosylation activity might share a common evolutionary origin. Overexpression of RhaT in hairy roots resulted in 13-, 2-, and 5-fold increases in linarin, isorhoifolin, and diosmin contents, respectively, indicating that RhaT is mainly involved in the biosynthesis of linarin. Our findings not only suggest that the substrate promiscuity of RhaTs contributes to the diversity of flavone rutinosides in Chrysanthemum species but also shed light on the evolution of flavone and flavanone rutinosides in distant taxa.

Co-Expression Network Analysis of the Transcriptome Identified Hub Genes and Pathways Responding to Saline–Alkaline Stress in Sorghum bicolor L.

“…In our study, we detected a total of 127 differentially expressed genes encoding AP2/ERF-ERF proteins, while the role of the WRKY family in response to environmental stress has also received widespread attention [78]. Overexpression of AtWRKY61 in transgenic Arabidopsis may respond to abiotic stresses by interacting with AtWRKY9 [79], and overexpression of WRKY3 in tobacco enhances plant salt tolerance [80]. In our study, SbWRKY61 (SORBI_3010G035300) and SbWRKY3 (SORBI_3008G107500) exhibited a co-upregulation trend consistent with previous research findings.…”

Identification and Characterization of Glycosyltransferases Involved in the Biosynthesis of Neodiosmin

“…The biochemical characteristics of recombinant Ach14791 (using 1 as the acceptor and UDP− Glu as the sugar donor) and Ach15849 (using 1a as the 18, and 24). Furthermore, Ach14791 could also catalyze the glycosylation of benzophenone (25) and simple phenolic compound derivatives (19)(20)(21)(22)(23)(24)26), producing O-glucosides. However, it failed to catalyze substrates, such as curcumin, alkaloids, triterpenes, hydroxynaphthalene, and anthraquinone.…”

“…For example, Ph1,6RhaT from Petunia hybrid played a role in regulating the rhamnosylation of anthocyanin-3- O -glucoside . Cs1,6RhaT and CsUGT79B28 were involved in the production of the bitter flavonoid 7- O -neohesperidoside in tea plants and the flavonoid 7- O -rutinoside in Chrysanthemum species, respectively. , GmF3G6″RhaT from Glycine max has been identified as a flavonol 3- O -glucoside 6″- O -rhamnosyltransferase, while AtUGT79B1 from Arabidopsis thaliana has been characterized as an anthocyanin 3- O -glucoside 2″- O -xylosyltransferase. , UGT94F1 from Veronica persica and UGT79B16 from Ipomoea nil have been characterized as anthocyanidin 3- O -glucoside 2″- O -glucosyltransferase. , …”

The haplotype‐resolved genome of diploid Chrysanthemum indicum unveils new acacetin synthases genes and their evolutionary history

“…The tissue-specific expression of flavonoids will aid in the dissection of biosynthetic pathway of key flavonoid components, which will pave the way for the biosynthetic production of these crucial biochemicals, especially in the context of the increasement of its market price by approximately 32.5% (Li et al, 2022). A recent study has deciphered the biosynthetic step from acacetin-7-O-glucoside to linarin in C. indicum (Wu et al, 2022). However, the upstream catalyzing enzymes remain unknown (Figure 3c; Figure S1), limiting the biosynthetic production of the major flavonoids in C. indicum.…”