Isolation of amaranthin synthetase from Chenopodium quinoa and construction of an amaranthin production system using suspension‐cultured tobacco BY‐2 cells

Abstract

Summary Betalains are plant pigments primarily produced by plants of the order Caryophyllales. Because betalain possesses anti‐inflammatory and anticancer activities, it may be useful as a pharmaceutical agent and dietary supplement. Recent studies have identified the genes involved in the betalain biosynthesis of betanin. Amaranthin and celosianin II are abundant in the quinoa ( Chenopodium quinoa Willd.) hypocotyl, and amaranthin comprises glucuronic acid bound to betanin; therefore, this suggests the existence of a glucuronyltransferase involved in the synthesis of amaranthin in the quinoa hypocotyl. To identify the gene involved in amaranthin biosynthesis, we performed a BLAST analysis and phylogenetic tree analysis based on sequences homologous to flavonoid glycosyltransferase, followed by expression analysis on the quinoa hypocotyl to obtain three candidate proteins. Production of amaranthin in a transient Nicotiana benthamiana expression system was evaluated for these candidates and one was identified as having the ability to produce amaranthin. The gene encoding this protein was quinoa amaranthin synthetase 1 ( CqAmaSy1 ). We also created a transgenic tobacco bright yellow‐2 ( BY ‐2) cell line wherein four betalain biosynthesis genes were introduced to facilitate amaranthin production. This transgenic cell line produced 13.67 ± 4.13 μ m (mean ± SEM ) amaranthin and 26.60 ± 1.53 μ m betanin, whereas the production of isoamaranthin and isobetanin could not be detected. Tests confirmed the ability of amaranthin and betanin to slightly suppress cancer cell viability. Furthermore, amaranthin was shown to significantly inhibit HIV ‐1 protease activity, whereas betanin did not.

Red-beet betalain pigments inhibit amyloid-β aggregation and toxicity in amyloid-β expressingCaenorhabditis elegans

“…Nematode feeding experiments have shown that the ingestion of specific betalain pigments produce lifespan-prolonging effects [26,27]. In our recent investigation, we confirmed that amaranthin, a betanin glucuronide, inhibits HIV-1 protease activity; however, betanin did not exhibit significant inhibitory effects [14].…”

“…Together, these results strongly suggest that betanin and isobetanin, which are the main components of the red-beet betanin extract inhibit the aggregation of Aβ. Previous studies have reported that the biological effects of betanin include suppression of cancer cell proliferation [11,14] and low-density lipoprotein oxidation [12,13].…”

“…Furthermore, Betanin, a major red pigment of beetroot extract, has been demonstrated to inhibit 6 low-density lipoprotein oxidation [12,13]. In our recent study, we found that amaranthin betalain pigment, which accumulates in amaranth and quinoa, inhibits HIV-1 protease activity [14]. Although various physiological functions of the betalain pigment have been reported, it is expected that many physiological activities have yet to be discovered.…”

A novel WD40-repeat protein involved in formation of epidermal bladder cells in the halophyte quinoa

“…Quinoa EBCs are involved not only in salt tolerance but also in resistance to ultraviolet (UV-B) stress 12,19 . Recently, our group and others sequenced an allotetraploid quinoa genome 9,20,21 and conducted gene functional analysis using the acquired data 22,23 . Furthermore, we generated quinoa mutants using ethylmethanesulfonate (EMS) and identified the genes responsible for several of the induced mutations 22 .…”

Virus-Mediated Transient Expression Techniques Enable Functional Genomics Studies and Modulations of Betalain Biosynthesis and Plant Height in Quinoa

“…Here, we show that ALSV-mediated transient expression techniques enable gene function studies in a wide variety of quinoa lines spanning all three sub-populations and can be used to alter the production of secondary metabolites such as pigments, carotenoids, and betalains, and also the plant morphology and architecture of quinoa. Although quinoa gene functions have been evaluated by the ectopic transient overexpression of exogenous genes in quinoa hairy roots, Nicotiana benthamiana leaves, and tobacco BY-2 suspension cells (Imamura et al, 2018(Imamura et al, , 2019(Imamura et al, , 2020, our findings presented here provide the quinoa research community with the gain-and lossof-function tools needed to analyze the functions of endogenous genes in planta and enable functional genomics in quinoa.…”