Flavonoid production in transgenic hop (Humulus lupulus L.) altered by PAP1/MYB75 from Arabidopsis thaliana L.

Abstract

Hop is an important source of secondary metabolites, such as flavonoids. Some of these are pharmacologically active. Nevertheless, the concentration of some classes as flavonoids in wild-type plants is rather low. To enhance the production in hop, it would be interesting to modify the regulation of genes in the flavonoid biosynthetic pathway. For this purpose, the regulatory factor PAP1/AtMYB75 from Arabidopsis thaliana L. was introduced into hop plants cv. Tettnanger by Agrobacterium-mediated genetic transformation. Twenty kanamycin-resistant transgenic plants were obtained. It was shown that PAP1/AtMYB75 was stably incorporated and expressed in the hop genome. In comparison to the wild-type plants, the color of female flowers and cones of transgenic plants was reddish to pink. Chemical analysis revealed higher levels of anthocyanins, rutin, isoquercitin, kaempferol-glucoside, kaempferol-glucoside-malonate, desmethylxanthohumol, xanthohumol, α-acids and β-acids in transgenic plants compared to wild-type plants.

Combinatorial analysis of lupulin gland transcription factors from R2R3Myb, bHLH and WDR families indicates a complex regulation of chs_H1 genes essential for prenylflavonoid biosynthesis in hop (Humulus LupulusL.)

“…While hop transformed by a single AtPAP1 gene was characterized by a significantly higher production of anthocyanins, rutin and isoquercetrin in cones and flowers in comparison to wild type plants [65], anthocyanins were not accumulated in the lupulin glands [52], most likely due to the lack of expression of the specific enzymatic machinery in these specialized structures. Conversely, hop TFs in s-M3B2W1 and M2B2W1 combinations were unable to co-activate the anthocyanin pathway in P. hybrida as found for the At PAP1B2 combination, thereby supporting the idea about functional specialization of lupulin-specific TFs.…”

"Transgenic" metabolome of hop, some aspects of its development and prospects of utilization.

“…Na uvedeném obrázku lze pozorovat, že u transgenního chmelu při dosažení fáze maturace dochází k červenému zbarvení hlávek a k akumulaci různých metabolitů, zejména anthocyaninu, rutinu a isoquercetinu. Některé ze zjiš-těných metabolitů nejsou bez zajímavosti pro farmacii a jsou tudíž předmětem dalšího studia (Gatica-Arias et al, 2012). Dekorativní charakter tohoto transgenního chmelu si přitom nic nezadá s okrasnými rostlinami.…”

“…It accumulates various metabolites like anthocyanins, rutin and isoquercetin. Some of metabolites found are of potential interest for pharmacology and, therefore, they be the subject of subsequent study (Gatica-Arias et al, 2012). The decorative character of this transgenic hop can compete with some ornamental plants.…”

“…2), the relative levels of chs_H1 mRNA were determined by RT qPCR and normalized against the elongation factor 1 housekeeping gene. 1,control infiltration of LBA 4404;2,chs_H1 gene;3,chs_H1 gene plus TF combination HlMyb2/HlbHLH2/HlWDR1;4,chs_H1 Gatica et al (2012). (Fig.…”

Metabolic Engineering of the Phenylpropanoid Pathway Enhances the Antioxidant Capacity of Saussurea involucrata

“…The PAP1 (Production of Anthocyanin Pigment 1) gene encoding a MYB transcription factor from Arabidopsis is a key player involved in the anthocyanin biosynthetic pathway [10]. Over-expression of PAP1 can effectively induce anthocyanin production in tobacco, hops, rose, Salvia miltiorrhiza and canola by regulating the related pathway genes, chalcone synthase (CHS), anthocyanidin synthase (ANS), flavonol synthase (FLS) etc [11]–[16]. The Lc (Leaf color) gene encodes a bHLH-type transcription factor identified from maize, which plays an important role in regulating anthocyanin production [17].…”