Association between differential gene expression and anthocyanin biosynthesis underlying the diverse array of petal colors in Zinnia elegans

Abstract

Zinnia elegans is a popular plant material widely used for flower beds and border. It shows abundant petal color variations, but the molecular mechanism of the petal color difference is still unknown. This study investigated and compared the difference of anthocyanin content, the expression of structural genes and sequence structure of ZeF3H transcript in six cultivars of Z. elegans ‘Dreamland’ series respectively with ivory, yellow, pink, rose, coral and red petals. Results showed that no anthocyanin is detected in ivory and yellow cultivars, while four acetylated anthocyanins, cyanidin 3-O-(6′'-acetyl)glucoside-5-O-glucoside, pelargonidin 3-O-(6′'-acetyl)glucoside-5-O-glucoside, cyanidin 3-O-(6′'-acetyl)glucoside, and pelargonidin 3-O-(6′'-acetyl)glucoside, have been detected in the petals of other four cultivars. The main anthocyanin type in coral and pink cultivars is pelargonidin, because lower expression of ZeF3′H in these two cultivars probably affects the formation of dihydroquercetin from dihydrokaempferol to ultimately produce cyanidin (Cy). But Cy is the main anthocyanin type in rose and red cultivars, which show the higher expression of ZeF3′H, and the greater amount of Cy derivatives and total anthocyanin content. What’s more, a premature termination codon caused by 5-bp insertion in ZeF3H transcripts should be responsible for no anthocyanin accumulation in ivory and yellow cultivars. Our study will lay foundation on revealing the molecular mechanism of petal coloration in Z. elegans.