Multiomic Analysis Elucidates the Reasons Underlying the Differential Metabolite Accumulation in Citrus Mature Leaves and Fruit Juice Sacs

Fruit
and leaf possess distinctly different metabolites. Here,
metabolites and transcriptome were compared between mature leaves
(ML) and juice sacs (JS) of Citrus grandis “Hirado Buntan” to investigate the possible reasons.
Results indicated that the remarkable difference in starch, total
flavonoids and carotenoids, l-ascorbate, and jasmonic acid
between ML and JS was tightly related to the expression levels of
their biosynthesis-related genes, while the significant difference
in abscisic acid and citrate was mainly related to the gene expression
level(s) of 9-cis-epoxycarotenoid dioxygenase and
proton pump genes, respectively. In addition, ATP citrate lyase probably
plays a key role in the levels of flavonoids between ML and JS via
providing different levels of acetyl-CoA. Taken together, these results
identified some key candidate genes responsible for the content of
a given metabolite and will contribute to research in regulating such
metabolite content in citrus fruits.