Analysis of suppression subtractive hybridization in differently expressed genes between red and green apple fruits

Most of the red and blue colors found in higher plants are influenced by anthocyanins and their pathways. Anthocyanin accumulation is regulated by MYB transcription factors. Some cultivars of apple indicate anthocyanin accumulation with a red color in the skin and, at times, even in the cortex core, but cultivars without anthocyanin production have green-colored skin indicative of chlorophyll accumulation. To obtain gene expression profiles from the apple cultivars with different flesh and skin colors, two apple cultivars, the red-colored 'Redfield' and the green-colored 'Greensleeves', were used. A cDNA suppression subtractive hybridization (SSH) library was established and analyzed. Six genes encoding methallothionein-like protein, chalcone isomerase, dirigent-like protein, brassinosteroid-6-oxidase, an unnamed protein product, and some unknown proteins were selected, and their expression was confirmed in 'Redfield' through virtual northern blot analysis. In 'Greensleeves', five genes encoding gibberellinregulated protein, a hypothetical 23.5 KD protein, anthranilate Nhydroxycinnamoyl/ benzoyltransferase and isoflavone reductase were chosen, and their upregulated transcriptional levels were identified. These selected genes were differently expressed between the two apple cultivars, suggesting that these genes may directly or indirectly regulate anthocyanin accumulation.