Genomic and transcriptomic analysis of eggplant’s fruits differing in anthocyanin content

Eggplant (Solanum melongena L.) is the third most important berry-producing crop in the Solanaceae family, after tomato and potato. Eggplants are highly variable in fruit color, ranging from white to green to dark violet. Black-purple fruits are the most economically valuable due to their high anthocyanin content. In field, a genotype bearing green fruits was identified as a natural mutant of the dark violet-fruited eggplant variety “Black Beauty” (BB). Morphological data confirmed that the mutant, "Green Beauty" (GB), is identical to BB except for berry peel color and calyx prickliness. Genomic and transcriptomic studies were conducted to understand the molecular basis of the peel color difference between BB and GB. Whole genome re-sequencing did not reveal high-impact polymorphisms in the coding sequence (CDS) of structural genes known to be involved in anthocyanin biosynthesis. RNA-seq analysis of BB and GB at three stages of fruit development showed that the majority of differentially expressed genes between BB and GB are the structural genes involved in anthocyanin production. Notably, part of the early genes (CHS, CHI, and F3H) and all the late genes (DFR, ANS, and UFGT) were downregulated or absent in GB. Data analysis is currently focusing on transcription factors belonging to the MBW complex (e.g. MYB, bHLH, WD40), which play a key role in regulating anthocyanin biosynthesis.