Simultaneous Treatment with Tebuconazole and Abscisic Acid Induces Drought and Salinity Stress Tolerance in Arabidopsis thaliana by Maintaining Key Plastid Protein Levels

Arabidopsis thaliana plants were treated simultaneously with the fungicide tebuconazole and the phytohormone abscisic acid (ABA). We carried out comparative proteomic and transcriptomic analysis against untreated controls under different stress regimes. The chemicals were applied 24 h before the onset of drought stress (removal of the nutrient medium) or salinity stress (hydroponic culture using 150 mM NaCl), and samples were taken during the stress treatments and after a 24 h recovery period. The combined chemical treatment protected plants against both forms of stress. Difference in-gel electrophoresis revealed 18 and 34 unique protein markers representing induced tolerance to drought and salinity stress, respectively. Most of the markers represented plastid functions (such as CO2 fixation and photosystem U activity), and their abundance was reduced under stress conditions but maintained at near normal levels in the treated plants. The corresponding transcripts were reduced in abundance primarily under drought stress but not salinity stress, indicating that the signal transduction pathways activated by tebuconazole/ABA treatment depend on the nature of the stress stimulus.