The fusicoccin story revisited

• Published in: Journal of experimental botany Vol. 75; no. 18; pp. 5531 - 5546
• Main Author: de Boer, Albertus H
• Format: Journal Article
• Language: English
• Published: UK Oxford University Press 27.09.2024
• Subjects: TORC1; 14-3-3 protein; innate immune response; ATPase; turgor control unit; H; channel; abscisic acid; K; ethylene; cytoplasmic pH; fusicoccin; Innate Immune Response; Turgor-Control-Unit (TCU); K+-channel; Cytoplasmic pH; Ethylene; Abscisic acid; H+-ATPase; Fusicoccin
• ISSN: 0022-0957; 1460-2431; 1460-2431
• DOI: 10.1093/jxb/erae300

Abstract Fusicoccin (FC) is one of the most studied fungal metabolites to date. The finding that the plasma membrane H+-ATPase in combination with 14-3-3 proteins acts as a high-affinity receptor for FC was a breakthrough in the field. Ever since, the binding of FC to the ATPase–14-3-3 receptor complex has taken center stage in explaining all FC-induced physiological effects. However, a more critical review shows that this is not evident for a number of FC-induced effects. This review challenges the notion that all FC-affected processes start with the binding to and activation of the plasma membrane ATPase, and raises the question of whether other proteins with a key role in the respective processes are directly targeted by FC. A second unresolved question is whether FC may be another example of a fungal molecule turning out to be a ‘copy’ of an as yet unknown plant molecule. In view of the evidence, albeit not conclusive, that plants indeed produce ‘FC-like ligands’, it is worthwhile making a renewed attempt with modern improved technology to answer this question; the answer might upgrade FC or its structural analogue(s) to the classification of plant hormone. In this review, two questions are addressed: are all effects that fusicoccin has on the physiology of plants the result of H+ -ATPase activation; and do plants produce fusicoccin(-like) molecules?