Enhanced flavonoid production in hairy root cultures of Scutellaria bornmuelleri by elicitor induced over-expression of MYB7 and FNSП2 genes

Abstract

For the purpose of the current study, hairy root induction in S. bornmuelleri, which is an important medicinal plant, was examined using a particular protocol. Accordingly, some factors such as four strain types of Agrobacterium rhizogenes (A4, A13, MSU440 and ATCC15834), three different explants, namely stem, petiole and leaf, two co-cultivation media, i.e. full and half-MS were studied. Besides, two inoculation methods including injection and immersion as well as three inoculation times (5, 7 and 10 min) were closely taken into account. Utilizing injection method by MSU440 strain, hairy root induction took place in stem explants, and a remarkable increase in transformation frequency (100%) was observed in half-strength MS medium. Methyl jasmonate (MeJA, 100 μM), methyl-b-cyclodextrin (b-CD, 0.7, 7 and 14 mM) and Chitosan (Chi, 50, 100 and 200 mg/l) were used either individually or in a combined way to elicitation. Based on the HPLC results, production of chrysin, wogonin and baicalein increased 9.15, 10.56 and 13.25 times after elicitation of hairy roots by MeJA + Chi. In addition, transcripts of FNSП2 and MYB7, two important genes involved in the flavonoid biosynthesis pathway, were studies. By applying Chi and MeJA + Chi elicitor, the expression of both genes increased noticeably. It can be concluded that the mentioned hairy root culture system of S. bornmuelleri can be an alternative to flavonoids production. Moreover, there is a direct and positive relationship between the expression of FNSП2 and MYB7 genes as well as the level of three flavonoids.