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Tonoplast-localized Ca 2+ pumps regulate Ca 2+ signals during pattern-triggered immunity in Arabidopsis thaliana
Ist Teil von
Proceedings of the National Academy of Sciences - PNAS, 2020-08, Vol.117 (31), p.18849-18857
Ort / Verlag
United States
Erscheinungsjahr
2020
Quelle
MEDLINE
Beschreibungen/Notizen
One of the major events of early plant immune responses is a rapid influx of Ca
into the cytosol following pathogen recognition. Indeed, changes in cytosolic Ca
are recognized as ubiquitous elements of cellular signaling networks and are thought to encode stimulus-specific information in their duration, amplitude, and frequency. Despite the wealth of observations showing that the bacterial elicitor peptide flg22 triggers Ca
transients, there remain limited data defining the molecular identities of Ca
transporters involved in shaping the cellular Ca
dynamics during the triggering of the defense response network. However, the autoinhibited Ca
-ATPase (ACA) pumps that act to expel Ca
from the cytosol have been linked to these events, with knockouts in the vacuolar members of this family showing hypersensitive lesion-mimic phenotypes. We have therefore explored how the two tonoplast-localized pumps, ACA4 and ACA11, impact flg22-dependent Ca
signaling and related defense responses. The double-knockout
exhibited increased basal Ca
levels and Ca
signals of higher amplitude than wild-type plants. Both the aberrant Ca
dynamics and associated defense-related phenotypes could be suppressed by growing the
seedlings at elevated temperatures. Relocalization of ACA8 from its normal cellular locale of the plasma membrane to the tonoplast also suppressed the
phenotypes but not when a catalytically inactive mutant was used. These observations indicate that regulation of vacuolar Ca
sequestration is an integral component of plant immune signaling, but also that the action of tonoplast-localized Ca
pumps does not require specific regulatory elements not found in plasma membrane-localized pumps.