Chemical Genetics Reveals Negative Regulation of Abscisic Acid Signaling by a Plant Immune Response Pathway

• DOI: 10.1016/j.cub.2011.04.045
• Publication Date: 2011-06-08T17:17:29Z
• Authors: Tae-Houn Kim; Felix Hauser; Tracy Ha; Shaowu Xue; Maik Böhmer; Noriyuki Nishimura; Shintaro Munemasa; Katharine Hubbard; Nora Peine; Byeong-ha Lee; Stephen Lee; Nadia Robert; Jane E. Parker; Julian I. Schroeder
• Keywords: 0303 health sciences; Agricultural and Biological Sciences(all); Biochemistry, Genetics and Molecular Biology(all); Gene Expression Profiling; Pseudomonas syringae; Thiones; Plants; 3. Good health; Small Molecule Libraries; 03 medical and health sciences; Piperidines; Gene Expression Regulation, Plant; Osmotic Pressure; Stress, Physiological; Plant Stomata; Abscisic Acid; Plant Proteins; Signal Transduction

Coordinated regulation of protection mechanisms against environmental abiotic stress and pathogen attack is essential for plant adaptation and survival. Initial abiotic stress can interfere with disease-resistance signaling [1-6]. Conversely, initial plant immune signaling may interrupt subsequent abscisic acid (ABA) signal transduction [7, 8]. However, the processes involved in this crosstalk between these signaling networks have not been determined. By screening a 9600-compound chemical library, we identified a small molecule [5-(3,4-dichlorophenyl)furan-2-yl]-piperidine-1-ylmethanethione (DFPM) that rapidly downregulates ABA-dependent gene expression and also inhibits ABA-induced stomatal closure. Transcriptome analyses show that DFPM also stimulates expression of plant defense-related genes. Major early regulators of pathogen-resistance responses, including EDS1, PAD4, RAR1, and SGT1b, are required for DFPM-and notably also for Pseudomonas-interference with ABA signal transduction, whereas salicylic acid, EDS16, and NPR1 are not necessary. Although DFPM does not interfere with early ABA perception by PYR/RCAR receptors or ABA activation of SnRK2 kinases, it disrupts cytosolic Ca(2+) signaling and downstream anion channel activation in a PAD4-dependent manner. Our findings provide evidence that activation of EDS1/PAD4-dependent plant immune responses rapidly disrupts ABA signal transduction and that this occurs at the level of Ca(2+) signaling, illuminating how the initial biotic stress pathway interferes with ABA signaling.