Identification of differentially expressed genes related to coloration in red/green mutant pear (Pyrus communis L.)

Fruit skin color is an important parameter of outer quality and plays an important role in attracting customers. In many plants, it is the result of coordinative regulation of anthocyanin pathway genes. In our study, the differential expression of cDNA library in a pair of pear mutant with red and green color was investigated to find candidate genes which might regulate the anthocyanin biosynthesis and control the coloration of pear. We constructed a cDNA library using the cDNA-amplified fragment length polymorphism approach to analyze the transcriptional differences between the original cultivar "Early red Doyenne du Comice" with high anthocyanin content in the peel and its green color mutant with comparatively low anthocyanin content. Altogether, 47 transcript-derived fragments, putatively involved in anthocyanin biosynthesis, primary metabolism, stress, and defense responses, were identified. The relationships of differentially expressed genes and coloration were investigated by quantitative real-time PCR with fruit skin samples at different developmental stages. A gene putatively involved in anthocyanin biosynthesis was found and named as PyMADS18. Its sequence is similar to genes reported in the literature as regulators of anthocyanin biosynthesis. The expression results indicate that PyMADS18 is likely to be involved in anthocyanin accumulation and regulation of anthocyanin synthesis in early fruit development of pear.