PBS3 coordinates the leaf specific outcome of abiotic and biotic stress crosstalk through salicylic acid mediated immune signaling
M. BERENS (1), K. Tsuda (1) (1) Max Planck Institute for Plant Breeding Research, Germany

Plants balance abiotic and biotic stress responses. For example, abiotic stresses suppress immunity mediated by the phytohormone salicylic acid (SA) via abscisic acid (ABA) signaling. Such a trade-off would be beneficial when plants face a single stress. However, plants simultaneously encounter multiple stresses in nature, and trade-offs may reduce plant fitness in combined stress conditions. Here, we found that plants distinctly control the outcome of crosstalk between abiotic and biotic stress in individual leaves. In older Arabidopsis thaliana leaves, ABA acted antagonistically on SA-induced PR1 expression while in younger leaves synergistically within a single plant. This was correlated to SA levels and immunity against the nonvirulent bacterial strain Pseudomonas syringae pv. tomato DC3000 hrcC (Pto hrcC). Likewise, suppression of immunity by salt stress was restricted to old leaves in an ABA-dependent manner. This leaf age-dependent crosstalk is genetically controlled since mutation in a single gene, AvrPphB susceptibility 3 (PBS3), was sufficient to completely block this mechanism. These results suggest that plants may assign distinct leaves for each stress (i.e. older leaves for abiotic stress and younger leaves for biotic stress), resulting in ensuring survival of a plant during combined stresses. Finally, this leaf-age dependent crosstalk was conserved in an A. thaliana relative, Arabidopsis lyrata, pointing to the importance of this mechanism during evolution.

Abstract Number: P16-441
Session Type: Poster