Phytohormone cross-talk during fruit ripening: linked biosynthesis and signaling

Numerous plant hormones play important roles in fruit maturity. Ethylene (ET) and abscisic acid (ABA) affect the ripening of climacteric and non-climacteric fruits, respectively. Auxins, gibberellin (GA), cytokinin (CK), jasmonic acid (JA), salicylic acid (SA), and brassinosteroid (BR) also regulate fruit ripening. Hormones' individual or combined effects on fruit ripening have long been one of hot topics in hormones research. It is now widely accepted that fruit ripening is regulated by a complex multi-hormonal crosstalks rather than by a simple antagonistic or synergistic interactions. While the importance of the interactions between multiple hormone signaling pathways is widely documented, integration of the recent advances in our understanding of the molecular events underlying this process during fruit ripening and senescence is not thoroughly addressed. Here we summarize the most advanced discoveries related to the hormone crosstalk underpinning the transition to ripening, with a particular emphasis on the interactions between hormonal signalings and developmental factors known to control fruit ripening. This sheds light on the molecular mechanisms leading to the genetic reprogramming underlying the fruit ripening process.