Fungal toxin fusicoccin enhances plant growth by upregulating 14-3-3 interaction with plasma membrane H+-ATPase

Abstract Fusicoccin-A (FC-A) is a diterpene glucoside produced by a pathogenic fungus. FC-A is phytotoxic and induces stomatal opening and leaf wilting, eventually leading to plant death. Here, we report that FC-A enhances plant growth by stabilizing the protein-protein interaction between plasma membrane (PM) H + -ATPase and 14-3-3 in guard cells, promoting stomatal opening and thus photosynthesis. Long-term treatment of Arabidopsis plants with FC-A resulted in ~ 30% growth enhancement. Structurally similar fusicoccin-J (FC-J) showed a similar degree of growth-promotion activity as FC-A, whereas the more hydrophilic fusicoccin-H (FC-H) exhibited no effect on plant growth, indicating that the enhancement of plant growth observed with FC-A and FC-J involves upregulation of the protein-protein interaction between PM H + -ATPase and 14-3-3 in guard cells, which promotes stomatal opening and photosynthesis.