Distinct early transcriptional regulations by turgor and osmotic potential changes in the root of Arabidopsis

In a context of climate change, deciphering signaling pathways leading to plant adaptation to drought, water availability, and salt tolerance is a crucial question. A common crossing point of these plant stresses is their impact on plant water potential, a composite physico-chemical variable reflecting the availability of water for the plant biological and biochemical processes such as growth or stomatal aperture. The water potential of plant cells is mainly driven by their turgor pressure and osmotic potential. Here we investigated the effect of a variety of osmotic treatments in the root of Arabidopsis plants grown in hydroponics. Measurement of the cortical cells turgor pressure with a cell pressure probe allowed to control the intensity of the treatments and, in particular, preserve the cortex from plasmolysis. Transcriptome analyses at early time point (15min) showed specific and quantitative transcriptomic responses for both osmotic and turgor pressures in the root. Our results highlight how water-related biophysical parameters can shape the transcriptome and provide putative candidates to explore further the early perception of water stress in plants. Col-0 wild-type plants were grown in a standard hydroponic solution. One part of the plants was transferred to the same hydroponic solution as a control for the osmotic pressure. The other part of the plants was transferred to the same hydroponic solution supplemented with various concentrations of various solutes : Sodium chloride at 25, 50, 75 or 100mM or Sorbitol at 50, 100 or 150mM or Polyethylene glycol 8000 at 75, 100, 125 or 150mM or Ethylene glycol at 50, 100, 150 or 200mM. Root collection was done 15 minutes after application of the osmotic treatments.