Whole-Plant Measure of Temperature-Induced Changes in the Cytosolic pH of Potato Plants Using Genetically Encoded Fluorescent Sensor Pt-GFP

Abstract

Cytosolic pH (pHcyt) regulates a wide range of cellular processes in plants. Changes in pHcyt occurring under the effect of different stressors can participate in signal transmission. The dynamics of pHcyt under the action of external factors, including significant factors for open ground crops such as temperature, remains poorly understood, which is largely due to the difficulty of intracellular pH registration using standard methods. In this work, model plants of potato (one of the essential crops) expressing a fluorescent ratiometric pH sensor Pt-GFP were created. The calibration obtained in vivo allowed for the determination of the pHcyt values of the cells of the leaves, which is 7.03 ± 0.03 pH. Cooling of the whole leaf caused depolarization and rapid acidification of the cytosol, the amplitude of which depended on the cooling strength, amounting to about 0.2 pH units when cooled by 15 °C. When the temperature rises to 35–40 °C, the cytosol was alkalized by 0.2 pH units. Heating above the threshold temperature caused the acidification of cytosol and generation of variation potential. The observed rapid changes in pHcyt can be associated with changes in the activity of H+-ATPases, which was confirmed by inhibitory analysis.