AUTHOR=Zhou Yeling , Vroegop-Vos Irene , Schuurink Robert C. , Pieterse Corné M. J. , Van Wees Saskia C. M. 

TITLE=Atmospheric CO2 Alters Resistance of Arabidopsis to Pseudomonas syringae by Affecting Abscisic Acid Accumulation and Stomatal Responsiveness to Coronatine

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00700

DOI=10.3389/fpls.2017.00700

ISSN=1664-462X

ABSTRACT=<p>Atmospheric CO<sub>2</sub> influences plant growth and stomatal aperture. Effects of high or low CO<sub>2</sub> levels on plant disease resistance are less well understood. Here, resistance of <italic>Arabidopsis thaliana</italic> against the foliar pathogen <italic>Pseudomonas syringae</italic> pv. <italic>tomato</italic> DC3000 (<italic>Pst</italic>) was investigated at three different CO<sub>2</sub> levels: high (800 ppm), ambient (450 ppm), and low (150 ppm). Under all conditions tested, infection by <italic>Pst</italic> resulted in stomatal closure within 1 h after inoculation. However, subsequent stomatal reopening at 4 h, triggered by the virulence factor coronatine (COR), occurred only at ambient and high CO<sub>2</sub>, but not at low CO<sub>2</sub>. Moreover, infection by <italic>Pst</italic> was reduced at low CO<sub>2</sub> to the same extent as infection by mutant <italic>Pst cor<sup>-</sup></italic>. Under all CO<sub>2</sub> conditions, the ABA mutants <italic>aba2-1</italic> and <italic>abi1-1</italic> were as resistant to <italic>Pst</italic> as wild-type plants under low CO<sub>2</sub>, which contained less ABA. Moreover, stomatal reopening mediated by COR was dependent on ABA. Our results suggest that reduced ABA levels at low CO<sub>2</sub> contribute to the observed enhanced resistance to <italic>Pst</italic> by deregulation of virulence responses. This implies that enhanced ABA levels at increasing CO<sub>2</sub> levels may have a role in weakening plant defense.</p>