Abstract
Antifungal activities of plant defense proteins are profoundly altered in the presence of sugars and inorganic cations such as calcium and potassium. Little is known at the molecular level of how these effects are mediated, but they have substantial biological implications for plant-pathogen interactions. These solute and cation effects are the subject of the present investigation. Sugars accumulating in ripening grapes were found to substantially increase activity of a coordinately accumulating antifungal chitinase and a PR5 protein against the important grape pathogens Guignardia bidwellii and Botrytis cinerea. This developmentally controlled response appears to constitute a novel defense mechanism developed in fruits. Biochemical and genetic analyses of the tobacco PR5 protein osmotin in a yeast-based system demonstrated that calcium materially increases the protein's antifungal activity by facilitating an extracellular interaction involving an acidic cleft region on the osmotin surface and phosphomannans on the yeast cell surface. Potassium also affects this interaction, but in the opposite manner, suppressing osmotin activity. Models of how these solute and ion effects occur are presented.
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Claims 4
Claim · model-written summary
Sugars accumulating in ripening grapes substantially increased chitinase antifungal activity against grape pathogens.
- Taxon
- grapese0
- Interactor
- Guignardia bidwellii
Phyllosticta ampelicidae0pathogen - Second interactor
- Botrytis cinerea
Botrytis cinereae0pathogen - Gene
- antifungal chitinasee0
- Compound
- Sugarse0
- Outcome
- activity of a coordinately accumulating antifungal chitinasee0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sugars accumulating in ripening grapes were found to substantially increase activity of a coordinately accumulating antifungal chitinase and a PR5 protein against the important grape pathogens Guignardia bidwellii and Botrytis cinerea.”
Claim · model-written summary
Sugars accumulating in ripening grapes substantially increased PR5 protein antifungal activity against grape pathogens.
- Taxon
- grapese0
- Interactor
- Guignardia bidwelliiPhyllosticta ampelicidae0pathogen
- Second interactor
- Botrytis cinereaBotrytis cinereae0pathogen
- Gene
- PR5 proteine0
- Compound
- Sugarse0
- Outcome
- activity of a coordinately accumulating antifungal chitinase and a PR5 proteine0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sugars accumulating in ripening grapes were found to substantially increase activity of a coordinately accumulating antifungal chitinase and a PR5 protein against the important grape pathogens Guignardia bidwellii and Botrytis cinerea.”
Claim · model-written summary
Calcium increased tobacco osmotin antifungal activity in a yeast-based system.
- Taxon
- tobacco
Nicotiana tabacume0 - Interactor
- yeaste0other
- Gene
- PR5 protein osmotine0
- Compound
- calciume0
- Outcome
- protein's antifungal activitye0
- Direction
- increasese0
- Qualifier
- yeast-based systeme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Biochemical and genetic analyses of the tobacco PR5 protein osmotin in a yeast-based system demonstrated that calcium materially increases the protein's antifungal activity by facilitating an extracellular interaction involving an acidic cleft region on the osmotin surface and phosphomannans on the yeast cell surface.”
Claim · model-written summary
Potassium suppressed tobacco osmotin activity.
Not reportedTaxon
Verbatim
t0“osmotin's antifungal activity”
e0“Potassium also affects this interaction, but in the opposite manner, suppressing osmotin activity.”