Production of glucosinolates, phenolic compounds and associated gene expression profiles of hairy root cultures in turnip (Brassica rapa ssp. rapa)

Abstract

Turnip (Brassica rapa ssp. rapa) is an important vegetable crop producing glucosinolates (GSLs) and phenolic compounds. The GSLs, phenolic compound contents and transcript levels in hairy root cultures, as well as their antioxidant, antimicrobial and anticancer activity were studied in turnip. Transgenic hairy root lines were confirmed by polymerase chain reaction (PCR) and reverse transcription-PCR. GSLs levels (glucoallysin, glucobrassicanapin, gluconasturtiin, glucobrassicin, 4-methoxyglucobrassicin, neoglucobrassicin and 4-hydroxyglucobrassicin) and their gene expression levels (BrMYB28, BrMYB29, BrMYB34, BrMYB51, BrMYB122, CYP79 and CYP83) significantly increased in hairy roots compared with that in non-transformed roots. Furthermore, hairy roots efficiently produced several important individual phenolic compounds (flavonols, hydroxybenzoic and hydroxycinnamic acids). Colorimetric analysis revealed that the highest levels of total phenol, flavonoid contents, and their gene expression levels (PAL, CHI and FLS) in hairy roots than non-transformed roots. Our study provides beneficial information on the molecular and physiological active processes that are associated with the phytochemical content and biosynthetic gene expression in turnip. Moreover, antioxidant activity, as measured by DPPH scavenging activity, reducing potential, phosphomolybdenum and ferrous ion chelating ability assays was significantly higher in hairy roots. Hairy root extracts exhibited higher antimicrobial activity against bacterial and fungal species. The extract of hairy roots showed inhibition of human breast and colon cancer cell lines.

Expression profiles of glucosinolate biosynthetic genes in turnip (Brassica rapa var. rapa) at different developmental stages and effect of transformed flavin‐containing monooxygenase genes on hairy root glucosinolate content

“…Turnip hairy root cultures were established on the basis of the methods of Chung et al . Explants from cotyledons with petiole of 7‐day‐old seedlings were used for the transformation.…”

In vitro plant tissue culture: means for production of biological active compounds

“…Hybrid systems, which include a liquid-and a gas phase, are reactors that attend the disadvantage of the null distribution uniformity of cells in gas-phase reactors, and the limitations of the mass transfer in liquid-phase reactors; these systems offer the best compromise between the two systems, used in alternate way (Srivastava and Srivastava 2007). Biomass measurement is one of the major challenges during scale-up of hairy roots culture, however, it is also important to determine the harvest capacity of secondary metabolites and their bioactivity, some examples are phenolic compounds (Ho et al 2017;Thiruvengadam et al 2014), xanthones (Vinterhalter et al 2015), glucosinolates (Chung et al 2016), tetraterpenoids (Thakore and Srivastava 2017), among others.…”

“…Transformed hairy roots have shown a higher biological activity, compared with non-transformed roots (Chung et al 2016;Jeong et al 2005;Vinterhalter et al 2015). However, it is important to determine the optimal number of subcultures to avoid somaclonal variations that can affect the yield and behavior of plant cell cultures (Martínez-Estrada et al 2017).…”

Biosynthesis and bioactivity of glucosinolates and their production in plant in vitro cultures

“…Thus, Park et al (2011) obtained hairy root cultures of N. officinale, observing that this transformation induced an increase in the levels of aromatic glucosinolates (gluconasturtiin,210 nmol/g DW) or indole glucosinolates such as glucobrassicin (20 nmol/g DW) and 4-methoxyglucobrassicin (180 nmol/g DW) ( Table 2). In the same way, B. rapa hairy root cultures produced via Agrobacterium rhizogenes-mediated transformation were used as a suitable alternative approach for the production of both indole and aliphatic glucosinolates (Chung et al 2016). In fact, this transformation significantly increased the amount of glucoallysin, glucobrassicanapin, gluconasturtiin, glucobrassicin, 4-hydroxy -and 4-methoxyglucobrassicin, and neoglucobrassicin, particularly gluconasturtiin enhanced 1.02-fold compared to control cultures (Table 2).…”