Iris domestica (iso)flavone 7- and 3'-O-Glycosyltransferases Can Be Induced by CuCl2

Xiang Zhang; Yan Zhu; Jun Ye; Ziyu Ye; Ruirui Zhu; Guoyong Xie; Yucheng Zhao; Minjian Qin

doi:10.3389/fpls.2021.632557

Iris domestica (iso)flavone 7- and 3'-O-Glycosyltransferases Can Be Induced by CuCl₂

Front Plant Sci. 2021 Feb 9:12:632557. doi: 10.3389/fpls.2021.632557. eCollection 2021.

Authors

Xiang Zhang^{1

2}, Yan Zhu^{1

2}, Jun Ye^{1

2}, Ziyu Ye^{1

2}, Ruirui Zhu^{1

2}, Guoyong Xie^{1

2}, Yucheng Zhao^{1

2}, Minjian Qin^{1

2}

Affiliations

¹ Department of Resources Science of Traditional Chinese Medicines, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, China.
² Key Laboratory of Modern Traditional Chinese Medicines (Ministry of Education), China Pharmaceutical University, Nanjing, China.

Abstract

In many plants, isoflavones are the main secondary metabolites that have various pharmacological activities, but the low water solubility of aglycones limits their usage. The O-glycosylation of (iso)flavones is a promising way to overcome this barrier. O-glycosyltransferases (UGTs) are key enzymes in the biosynthesis of (iso)flavonoid O-glycosides in plants. However, limited investigations on isoflavonoid O-UGTs have been reported, and they mainly focused on legumes. Iris domestica (L.) Goldblatt et Mabberley is a non-legume plant rich in various isoflavonoid glycosides. However, there are no reports regarding its glycosylation mechanism, despite the I. domestica transcriptome previously being annotated as having non-active isoflavone 7-O-UGTs. Our previous experiments indicated that isoflavonoid glycosides were induced by CuCl₂ in I. domestica calli; therefore, we hypothesized that isoflavone O-UGTs may be induced by Cu²⁺. Thus, a comparative transcriptome analysis was performed using I. domestica seedlings treated with CuCl₂, and eight new active BcUGTs were obtained. Biochemical analyses showed that most of the active BcUGTs had broad substrate spectra; however, substrates lacking 5-OH were rarely catalyzed. Real-time quantitative PCR results further indicated that the transcriptional levels of BcUGTs were remarkably induced by Cu²⁺. Our study increases the understanding of UGTs and isoflavone biosynthesis in non-legume plants.

Keywords: (iso)flavones; Iris domestica (Belamcanda chinensis) copper chloride; UGT; induce; transcriptome.