Towards an integrated molecular understanding of plant hormones

From seed dormancy to pathogen attacks and senescence, many events in a plant's life are critically controlled by low-molecular-weight signaling molecules, called plant hormones. These master regulators include abscisic acid, auxins, brassinosteroids, cytokinins, ethylene, gibberellins, jasmonates, salicylates, and strigolactones. Years of research have unveiled multiple aspects of their biosynthesis, transport, signaling, functions, and interactions. With this knowledge, complex molecular networks have been established and refined over time in an attempt to explain how plant hormones collectively mediate physiological processes, under a wide range of contexts and at various developmental stages. In this context, we aim to shed light on the global molecular framework of plant hormonal signaling. To do so, we first step back and offer a deconvolution of plant hormonal pathways, by addressing their biosynthesis, transport, and signaling. We then explore how hormonal pathways interfere with each other at a molecular level, mostly through transcriptional regulation and protein-protein interactions. We further discuss directions to fine-tune our fundamental understanding of plant hormonal control, and finally, we highlight how this knowledge can be translated into applied prospects to tackle unprecedented agricultural challenges.