Artificial microRNA mediated silencing of cyclase and aldo–keto reductase genes reveal their involvement in the plumbagin biosynthetic pathway

A chromosome-level genome reveals genome evolution and molecular basis of anthraquinone biosynthesis in Rheum palmatum

“…However, the experiment was conducted in prokaryotic cells, which may not fully recapitulate the conditions in eukaryotes. Additionally, recent findings have implicated PKR in naphthoquinone biosynthesis in Plumbago zeylanica , hinting at the involvement of multiple coenzymes in anthraquinone biosynthesis [ 23 ]. This could explain why the in vivo function of ALS yet to be confirmed and underscores the need for further investigation in eukaryotic expression system, especially in R. palmatum , to elucidate the roles of RpALS and other coenzymes.…”

“…Coding sequences were matched against the final assembled genome using BLASTn to detect any potentially missed genes. In addition, we retrieved perakine reductase in Rauvolfia serpentina (AY766462.1) and olivetolic acid cyclase in Cannabis sativa (JN679224.1) from GenBank to predict PKR and PKC, respectively [ 23 ]. These seed sequences were searched against R. palmatum proteins using BLAST, setting an e-value threshold of 1 × 10 − 5 .…”

“…In R. palmatum , four PKS enzymes—RpALS, RpBAS and two RpCHSs—have been identified, but none can catalyze the production of polyketide compounds [ 19 – 21 ]. It is worth noting that a reductase (polyketide reductase, PKR) and a cyclase (polyketide cyclase, PKC) are speculated to catalyze subsequent process following octaketide formation [ 22 , 23 ]. Further modifications like oxidation, methylation and glycosylation are believed to be catalyzed by cytochrome P450 monooxygenases (CYP), O -methyl transferases (OMT) and UDP-glucuronosyltransferase (UGT), leading to the formation of various anthraquinone and the glycosides.…”

Distribution of Acetogenic Naphthoquinones in Droseraceae and Their Chemotaxonomic Utility

“…Between the distant orders, the dualism between octaketides and hexaketides may indicate similar selective pressures that have resulted in similar developments; thus, the dualism as such is supposedly convergent. The genetics of these polyketides is, however, only poorly understood, and beyond a few expectable enzymes catalyzing individual biosynthetic steps [10], no comparative sequence data are known to reflect the obvious metabolic similarities nor the anticipated genetic differences.…”

“…Outside Nepenthales, noteworthy records of plumbagin and/or ramentaceone are limited to the phylogenetically distant families Ebenaceae (Ericales) and Iridaceae (Asparagales) [3]. Due to their indicative substitution patterns, it is assumed that the characteristic naphthoquinones in Nepenthales, Ebenaceae and Iridaceae are formed via the acetate-polymalonate route with hexaketide and 1,8-dihydroxy-3-methylnaphthalene intermediates [10]. A number of biosynthetic precursors, structural variants and di-or polymers have been described (e.g., droserone, isoshinanolone, shinanolone, 7methylnaphthazarin, dihydroplumbagin, maritinone, mamegakinone [1,11], Figure 3).…”