The aim of this study was to quantify the contents of individual quercetin glycosides in red, yellow and chartreuse onion by High Performance Liquid Chromatography (HPLC) analysis. Acid hydrolysis of individual quercetin glycosides using 6 M hydrochloric acid guided to identify and separate quercetin 7,4'-diglucoside, quercetin 3-glucoside, quercetin 4'-glucoside, and quercetin. The contents of total quercetin glycosides varied extensively among three varieties (ranged from 16.10 to 103.93 mg/g DW). Quercetin was the predominant compound that accounted mean 32.21 mg/g DW in red onion (43.6% of the total) and 127.92 mg/g DW in chartreuse onion (78.3% of the total) followed by quercetin 3-glucoside (28.83 and 24.16 mg/g DW) respectively. Quercetin 3-glucoside levels were much higher in yellow onion (43.85 mg/g DW) followed by quercetin 30.08 mg/g DW. Quercetin 4'-glucoside documented the lowest amount that documented mean 2.4% of the total glycosides. The varied contents of glycosides present in the different onion varieties were significant.

The development of an efficient protocol for successful hairy root induction by Agrobacterium rhizogenes is the key step toward an in vitro culturing method for the mass production of secondary metabolites. The selection of an effective Agrobacterium strain for the production of hairy roots is highly plant species dependent and must be determined empirically. Therefore, our goal was to investigate the transformation efficiency of different A. rhizogenes strains for the induction of transgenic hairy roots in Fagopyrum tataricum ‘Hokkai T10’ cultivar; to determine the expression levels of the polypropanoid biosynthetic pathway genes, such as FtPAL, FtC4H, Ft4CL, FrCHS, FrCH1, FrF3H, FtFLS1, FtFLS2, FtF3, H1, FtF3,H2, FtANS, and FtDFR; and to quantify the in vitro synthesis of phenolic compounds and anthocyanins. Among different strains, R1000 was the most promising candidate for hairy root stimulation because it induced the highest growth rate, root number, root length, transformation efficiency, and total anthocyanin and rutin content. The R1000, 15834, and A4 strains provided higher transcript levels for most metabolic pathway genes for the synthesis of rutin (22.31, 15.48, and 13.04 µg/mg DW, respectively), cyanidin 3-O-glucoside (800, 750, and 650 µg /g DW, respectively), and cyanidin 3-O-rutinoside (2410, 1530, and 1170 µg /g DW, respectively). A suitable A. rhizogenes strain could play a vital role in the fast growth of the bulk amount of hairy roots and secondary metabolites. Overall, R1000 was the most promising strain for hairy root induction in buckwheat.