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Tenuazonic acid from Stemphylium loti inhibits the plant plasma membrane H + ‐ATPase by a mechanism involving the C‐terminal regulatory domain
Author(s) -
Bjørk Peter K.,
Rasmussen Silas A.,
Gjetting Sisse K.,
Havshøi Nanna W.,
Petersen Thomas Isbrandt,
Ipsen Johan Ø.,
Larsen Thomas O.,
Fuglsang Anja T.
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16398
Subject(s) - apoplast , atpase , biochemistry , phytotoxin , biology , arabidopsis thaliana , fusicoccin , enzyme , toxin , cell wall , mutant , gene
Summary Pathogenic fungi often target the plant plasma membrane (PM) H + ‐ATPase during infection. To identify pathogenic compounds targeting plant H + ‐ATPases, we screened extracts from 10 Stemphylium species for their effect on H + ‐ATPase activity. We identified Stemphylium loti extracts as potential H + ‐ATPase inhibitors, and through chemical separation and analysis, tenuazonic acid (TeA) as a potent H + ‐ATPase inhibitor. By assaying ATP hydrolysis and H + pumping, we confirmed TeA as a H + ‐ATPase inhibitor both in vitro and in vivo . To visualize in planta inhibition of the H + ‐ATPase, we treated pH‐sensing Arabidopsis thaliana seedlings with TeA and quantified apoplastic alkalization. TeA affected both ATPase hydrolysis and H + pumping, supporting a direct effect on the H + ‐ATPase. We demonstrated apoplastic alkalization of A. thaliana seedlings after short‐term TeA treatment, indicating that TeA effectively inhibits plant PM H + ‐ATPase in planta . TeA‐induced inhibition was highly dependent on the regulatory C‐terminal domain of the plant H + ‐ATPase. Stemphylium loti is a phytopathogenic fungus. Inhibiting the plant PM H + ‐ATPase results in membrane potential depolarization and eventually necrosis. The corresponding fungal H + ‐ATPase, PMA1, is less affected by TeA when comparing native preparations. Fungi are thus able to target an essential plant enzyme without causing self‐toxicity.