PacCOP1 negatively regulates anthocyanin biosynthesis in sweet cherry (Prunus avium L.).

Light is a key environmental factors affecting anthocyanin accumulation in plants. Ubiquitin E3 ligase COP1 has been proved to be a negative regulator involved in light-regulated plant development process, whereas the function and expression specificity of COP1 in anthocyanin biosynthesis in sweet cherry remains unclear. In the present study, we identified a COP1 in sweet cherry, named PacCOP1 , it exhibited apparent different expression patterns in red-colored 'Hongdeng' and bi-colored 'Satonishiki', with increasing trend largely in 'Satonishiki', but decreasing trend in 'Hongdeng' after veraison, which was contrary to their variation tendency of anthocyanin content. While the expression abundance of anthocyanin biosynthesis related genes were largely increased after veraison, in accordance with anthocyanin content. Correlation analysis proved that the expression of PacCOP1 was negative correlated with the major genes on anthocyanin accumulation in 'Hongdeng' and 'Satonishiki' fruit, in especial Pac DFR, Pac ANS, Pac MYBA and Pac bHLH33. Furthermore, over-expression of PacCOP1 in Arabidopsis displayed increased COP1 transcript level with negligible pigmentation and corresponding lower expression level of AtPAP1 , AtDFR , AtLDOX , and AtUFGT. These results revealed the negative regular role of PacCOP1 in anthocyanin biosynthesis by repressing the PacMYBA transcription level, followed by down-regulating the structural genes expression abundance, eventually leading to attenuated anthocyanin accumulation in fruits. • A novel Ubiquitin E3 ligase gene COP1 was identified from sweet cherry, named PacCOP1. • PacCOP1 exhibited apparent different expression patterns in red- and bi-colored cultivars, contrary to that of anthocyanin content. • The expression level of PacCOP1 was negative correlated with mRNA abundance of Pac DFR, Pac ANS, Pac MYBA and Pac bHLH33. [ABSTRACT FROM AUTHOR]