Interlinked regulatory loops of ABA catabolism and biosynthesis coordinate fruit growth and ripening in woodland strawberry

Significance Using strawberry fruit as a model system, we uncover the mechanistic interactions between auxin, gibberellic acid (GA), and abscisic acid (ABA) that regulate the entire process of fruit development. Interlinked regulatory loops control ABA levels during fruit development. During the early stages, auxin/GA turns on a feedback loop to activate the removal of ABA via FveCYP707A4a -dependent catabolism needed for fruit growth. Down-regulation of auxin/GA results in the suppression of the feedback loop and the activation of the ABA biosynthesis-dependent feedforward loop, leading to a steep ABA accumulation for fruit ripening. The interlinked regulatory loops provide a conceptual framework that underlies the connection between the regulation of fruit growth and that of ripening as well as a molecular basis for manipulation of fruit sizes and ripening times.