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.