Functional characterization of two flavone synthase II members in citrus

Abstract Polymethoxylated flavones (PMFs), the main form of in citrus, are derived from flavone branch flavonoid biosynthesis pathway. Flavone synthases (FNSs) enzymes that catalyze synthesis flavanones. However, FNS citrus has not been characterized yet. Here, we identified two type II FNSs, designated CitFNSII-1 and CitFNSII-2, based on phylogenetics transcriptome analysis. Both recombinant CitFNSII-2 proteins directly converted naringenin, pinocembrin, liquiritigenin to corresponding yeast. In addition, transient overexpression respectively, peel significantly enhanced accumulation total PMFs, while virus-induced genes silencing simultaneously reduced expression levels both PMF content seedlings. presented distinct patterns different cultivars as well developmental stages. Methyl salicylate (MeSA) treatment PMFs Citrus sinensis fruit but did affect expression. These results indicated participated regulatory mechanism governing their might be specific. Our findings improved understanding pathway laid foundation for further investigation regulation.