High Light Triggers Flavonoid and Polysaccharide Synthesis through DoHY5-Dependent Signaling in Dendrobium officinale
Published:29 May2023 Source:The Plant Journal
D. officinale is a multifunctional plant, which has medicinal, edible and ornamental functions. Polysaccharides and flavonoids, including anthocyanins, are important components of D. officinale that largely determine the nutritional quality and consumer appeal. There is need to study the potential molecular regulatory mechanisms in anthocyanin and polysaccharide biosynthesis, to enhance D. officinale quality and market value.
Here, we report that high light induced the accumulation of polysaccharides, particularly mannose, as anthocyanin accumulation, resulting in red stems. Metabolome and transcriptome analysis found that most of the flavonoids showed large changes in abundance, and flavonoid and polysaccharides biosynthesis pathway was significantly activated under HL treatment. Interestingly, DoHY5's expression was also highly induced. Biochemical analyses demonstrated that DoHY5 directly binds the promoters of DoF3H1 (involved in anthocyanin biosynthesis), DoGMPP2 and DoPMT28 (involved in polysaccharide biosynthesis) to activate their expression, thereby promoting anthocyanin and polysaccharide accumulation in D. officinale stems. DoHY5 silencing decreased flavonoid- and polysaccharide-related gene expression and reduced anthocyanin and polysaccharide accumulation, whereas DoHY5 overexpression had the opposite effects. Notably, naturally occurring red-stemmed D. officinale plants similarly have high levels of anthocyanin and polysaccharide accumulation and biosynthetic gene expression.
Our results reveal a previously undiscovered role of DoHY5 in co-regulate anthocyanin and polysaccharide biosynthesis under high condition, which will further our understanding of the mechanisms of stem color and nutritional quality formation in D. officinale. Collectively, our results propose a robust and simple strategy for significantly increasing anthocyanin and polysaccharide, and subsequently improve the nutritional quality of D. officinale.