5. Conclusion
Our RNA-seq analyses from the time of fruit ripening show that both red and blue wavelength are capable of inducing a high number of up-regulated genes and metabolic pathways, including flavonoid, phenylpropanoid, carotenoid, terpenoid backbone biosynthetic pathways and sugar metabolism. Blue and especially red light were effective in inducing anthocyanin and delphinidin accumulation but through different signal transduction routes. The blue light triggered early photomorphogenesis via CRY2/COP1 interaction that potentially combined with positive regulators, such as MYBA and HY5 to induce the expression of anthocyanin biosynthetic genes during onset of ripening. Red light treatment instead positively up-regulatedPhyB and all the major flavonoid genes, including the anthocyanin (UFGT ) and delphinidin (F3’5’H ) routes, key ABA biosynthetic gene (NCED ) and ABA degradingABA-8’hydroxylase genes. Our results provide an insight into the role of endogenous ABA accumulation and degradation as positive signaling factors leading to increased levels of anthocyanin accumulation via the ABA-signal transduction mechanism during the ripening process under red-light. We also found the expression of SNARE complex-related vesicle trafficking genes to be highly expressed in red light treated berries, which might provide clues into the possible sequestration and transport mechanisms via endosomes in tissues with higher anthocyanin accumulation, but need further investigation. Our high-quality transcriptome dataset will be a useful genomics resource in future bilberry research and Vaccinium breeding programs.