UV-B promotes flavonoid biosynthesis by regulating the LncNAT3-GbMYB6 module in Ginkgo biloba

Ginkgo biloba leaves represent a rich source of medicinal compounds, particularly flavonoids, which are widely recognized for their therapeutic effect in cardiovascular and cerebrovascular diseases. Ultraviolet-B (UV-B) radiation stands out as a pivotal environmental factor influencing the flavonoid biosynthesis in G. biloba leaves. Although the role of UV-B in regulating flavonoid biosynthesis has been previously investigated, the contribution of long non-coding RNAs (lncRNAs) to this biosynthetic process remains largely uncharted. In this study, we observed a marked increase in the flavonoid content of G. biloba leaves following UV-B radiation. Utilizing strand-specific RNA sequencing (ssRNA-seq) on leaves with and without UV-B exposure, we discerned a cohort of 23,724 lncRNAs, with 897 exhibiting differential expression. By constructing a regulatory network involving these differentially expressed lncRNAs and flavonoid-related MYBs, we identified the LncNAT3-GbMYB6 as a key novel regulatory module. Our findings indicate that LncNAT3 may negatively modulate flavonoid biosynthesis by downregulating the expression of GbMYB6. Further experiments, including overexpression and gene silencing of GbMYB6, confirmed its role as a transcription factor that actively promotes flavonoid biosynthesis. This research sheds light on the crucial role of the novel regulatory module LncNAT3-GbMYB6 in modulating flavonoid biosynthesis in response to UV-B radiation, offering new insights into the complex interplay between environmental factors and plant metabolism.