Transcriptomic Analysis of Red-Fleshed Apples Reveals the Novel Role of MdWRKY11 in Flavonoid and Anthocyanin Biosynthesis

In
plants, flavonoids are important secondary metabolites that
contribute to the nutritional quality of many foods. Apple is a popular
and frequently consumed food because of its high flavonoid content.
In this study, flavonoid composition and content were detected and
compared between red- and white-fleshed apples in a BC1 hybrid population using ultraperformance liquid chromatography–quadrupole
time-of-flight mass spectrometry. Transcriptomic analysis of the red-
and white-fleshed apples was then performed using RNA-seq technology.
By screening differentially expressed genes encoding transcription
factors, we unearthed a WRKY-family transcription factor designated
MdWRKY11. Overexpression of MdWRKY11 promoted the expression of F3H, FLS, DFR, ANS, and UFGT and increased the accumulation
of flavonoids and anthocyanin in apple calli. Our findings explored
the novel role of MdWRKY11 in flavonoid biosynthesis and suggest several
other genes that may also be potentially involved. This provides valuable
information on flavonoid synthesis for the breeding of elite red-fleshed
apples.