Expression Analysis of Anthocyanin Biosynthetic Genes in Different Colored Sweet Cherries (Prunus avium L.) During Fruit Development

To identify the key enzymes involved in anthocyanin synthesis in sweet cherry (Prunus avium L.), the differences in anthocyanin biosynthetic gene expressions were investigated in the samples (mix of peel and flesh) of a red-colored cultivar (‘Hongdeng’) and a bicolored cultivar (‘Caihong’) during fruit development. The expression of six anthocyanin synthetic genes in cherry (PacCHS, PacCHI, PacF3H, PacDFR, PacANS, and PacUFGT) was analyzed by quantitative real-time PCR and Western blot analysis. Meanwhile, the changes in anthocyanin contents were measured by ultra-performance liquid chromatography. The expression of anthocyanin synthetic genes and the anthocyanin contents were much higher in ‘Hongdeng’ than in ‘Caihong’ fruits. Gene transcription and translation and anthocyanin accumulation all started approximately at the end of the pit-hardening period and reached a maximum at maturation. All six genes were significantly correlated with anthocyanin accumulation in ‘Hongdeng’ and PacCHS had the highest direct effect. However, only PacUFGT was significantly correlated with anthocyanin accumulation in ‘Caihong’. Anthocyanin biosynthesis in sweet cherry seems to be regulated mostly at the transcript levels. CHS appears to be the key enzyme involved in anthocyanin synthesis in ‘Hongdeng’, while UFGT is involved in anthocyanin synthesis in ‘Caihong’ fruits.