Auxin Interactions with Other Hormones in Plant Development

Abstract

Auxin is a crucial growth regulator that governs plant development and responses to environmental perturbations. It functions at the heart of many developmental processes, from embryogenesis to organ senescence, and is key to plant interactions with the environment, including responses to biotic and abiotic stimuli. As remarkable as auxin is, it does not act alone, but rather solicits the help of, or is solicited by, other endogenous signals, including the plant hormones abscisic acid, brassinosteroids, cytokinins, ethylene, gibberellic acid, jasmonates, salicylic acid, and strigolactones. The interactions between auxin and other hormones occur at multiple levels: hormones regulate one another's synthesis, transport, and/or response; hormone-specific transcriptional regulators for different pathways physically interact and/or converge on common target genes; etc. However, our understanding of this crosstalk is still fragmentary, with only a few pieces of the gigantic puzzle firmly established. In this review, we provide a glimpse into the complexity of hormone interactions that involve auxin, underscoring how patchy our current understanding is.

Brassinosteroids Mitigate Cadmium Effects in Arabidopsis Root System without Any Cooperation with Nitric Oxide

“…The normal formation and activity of the quiescent center (QC) in the root apical meristems is known to be under auxin control [ 17 , 21 ], but Cd disrupts the QC in both PR and LRs/ARs of Arabidopsis [ 19 , 22 , 23 ], and affects the endogenous IAA distribution in the root apices monitored by the use of a DR5::GUS auxin-reporter line [ 19 , 24 ]. Auxin and BRs have overlapping activities with many target genes in common [ 25 ]. In Arabidopsis PR, BRs are required to control QC identity in addition to auxin [ 26 , 27 ], and interact with auxin signaling to promote LR growth [ 9 , 28 ].…”

Action of Salicylic Acid on Plant Growth

“…SA also interacts with other hormones involved in the regulation of cell division and expansion, such as auxin, GA, and ethylene (ET), to modulate plant and organ growth ( Ari et al, 2020 ; Emamverdian et al, 2020 ; Mazzoni-Putman et al, 2021 ; Pokotylo et al, 2021 ).…”

Interplays between auxin and GA signaling coordinate early fruit development

“…Given the crosstalk of auxin with many different plant hormones [ 77 ], it is not surprising that auxin treatment promotes the expression of the GA biosynthesis genes FveGA20OX and FveGA3OX in the early stage of strawberry fruit growth [ 8 ]. Both auxin and GA promote fruit growth, but auxin and GA have clearly different effects on fruit shape formation and strawberry fruit development [ 8 , 26 ].…”