An Integrated Transcriptome and Proteome Analysis Reveals New Insights into Russeting of ‘Golden Delicious’ Apple

Apple skin russeting naturally occurs in many varieties, particularly in 'Golden Delicious' and its pedigree, and is regarded as a non-invasive physiological disorder partly caused by excessive deposition of lignin. However, the understanding of its molecular mechanism is still limited. In this study, we used iTRAQ and RNA-seq to detect the changes in the expression levels of genes and proteins in three developmental stages of russeting formation, in russeted and non-russeted skin of 'Golden Delicious' apple. 2856 differentially expressed genes and 942 differentially expressed proteins in the comparison groups were detected at the transcript level and protein level, respectively. A correlation analysis of the transcriptomics and proteomics data revealed that four genes (MD03G1059200, MD08G1009200, MD17G1092400 and MD17G1225100) involved in lignin biosynthesis are significant changes during apple russeting formation. Additionally, 92 transcription factors, including 4 LIM transcription factors may be involved in apple russeting formation. Among them, one LIM transcription factor (MD15G1068200) was capable of binding to the PAL-box like (CCACTTGAGTAC) element, which indicated it was potentially involved in lignin biosynthesis. This study will provide further views on the molecular mechanisms controlling apple russeting formation. mRNA profiles of DAF30，DAF60 and DAF 150 of un-bagging (CK) and bagging (T), in apple, using BGISEQ-500