Abstract
Flavonoids are mainly associated with growth, development, and responses to diverse abiotic stresses in plants. A growing amount of data have demonstrated the biosynthesis of flavonoids through multienzyme complexes of which the membrane-bounded cytochrome P450 supergene family shares a crucial part. However, the explicit regulation mechanism of Cytochrome P450s related to flavonoid biosynthesis largely remains elusive. In the present study, we reported the identification of a stress-tolerant flavonoid biosynthetic CtCYP82G24 gene from Carthamus tinctorius. The transient transformation of CtCYP82G24 determined the subcellular localization to the cytosol. Heterologously expressed CtCYP82G24 was effective to catalyze the substrate-specific conversion, promoting the de novo biosynthesis of flavonoids in vitro. Furthermore, a qRT-PCR assay and the accumulation of metabolites demonstrated that the expression of CtCYP82G24 was effectively induced by Polyethylene glycol stress in transgenic Arabidopsis. In addition, the overexpression of CtCYP82G24 could also trigger expression levels of several other flavonoid biosynthetic genes in transgenic plants. Taken together, our findings suggest that CtCYP82G24 overexpression plays a decisive regulatory role in PEG-induced osmotic stress tolerance and alleviates flavonoid accumulation in transgenic Arabidopsis.
Highlights
During natural flavonoid biosynthesis, chalcone synthase (CHS) utilizes phenylpropanoids and malonyl-CoA as general substrates to catalyze the phenylpropanoid pathway in plants
The candidate CYP450 was named according to the shared homology with reference plant (CtCYP82G24)
Our findings presented the discovery and characterization of a new CtCYP82G24 isolated from Carthamus tinctorius using an expressed sequence homology-based approach followed by green fluorescent protein (GFP) tagging and expression analysis in a transgenic system
Summary
Chalcone synthase (CHS) utilizes phenylpropanoids and malonyl-CoA as general substrates to catalyze the phenylpropanoid pathway in plants. Various groups of multienzyme complexes are known to catalyze the biochemical reactions of plant physiological pathways and their adaptation to ever-changing environments [2,3]. These complexes of enzymes are mainly located in the cytosol and found embedded near the inner side of the endoplasmic reticulum (ER). The ER-bound enzyme complex belongs to the cytochrome P450 superfamily [4,5]. In most of the plant species, cytochrome P450 is found abundantly and produces multiple groups of secondary metabolites through hydroxylation and
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