Dynamic Changes of Phenolic Compounds and Their Associated Gene Expression Profiles Occurring during Fruit Development and Ripening of the Donghong Kiwifruit

The newly released Donghong kiwifruit
is a promising commercial
cultivar. The dynamic changes of major phenolic compounds (flavonols,
flavanols, phenolic acids, and anthocyanins) during the representative
stages of fruit development and ripening of the Donghong kiwifruit
were determined by high-performance liquid chromatography. The corresponding
time-course transcriptional changes were evaluated using the combined
analysis of RNA-Seq and qRT-PCR. The most predominant phenolic compound
in the Donghong kiwifruit was epicatechin. Cyanidin 3-O-[2-O-(β-xylosyl)-β-galactoside] and cyanidin 3-O-β-galactoside were two essential anthocyanins detected. Candidate
genes and pathways involved in phenolic compounds biosynthesis were
highlighted. The structural genes (AcLDOX2, Ac5GGT1, and Ac5AT2) and the transcription factor (bHLH74-2) were strongly associated with anthocyanin biosynthesis. AcMYB4-1 may be a novel transcription factor that reduces
anthocyanin accumulation. Results from the study may be a very useful
supplement to current knowledge of molecular mechanisms to elucidate
coloration in the red-fleshed kiwifruit and could help breeders modify
the kiwifruit germplasm.