Influence of exogenous NO donator and variations in the Ca~(2+) content on transport activity related to tonoplast proton pumps in ontogenesis and under hyperosmotic stress

摘要

The changes in transport activity of tonoplast proton pumps under the influence of exogenous NO donator and modulation of Ca~(2+) concentration jointly and separately were investigated at different stages of ontogenesis and under hyperosmotic stress. The results suggest that both exogenous NO donator and Ca~(2+) ions can influence the activity of transport processes related to tonoplast and this influence is especially evident in the period of growth and accumulation of metabolites. Under hyperosmotic stress, H~+-pyrophosphatase plays a more important role than H~+-ATPase: the activity of the former increases 2.3-fold compared to the control osmotic conditions, whereas the activity of H~+-ATPase is practically unchanged. H~+-pyrophosphatase was more responsive to the presence of exogenous NO donator and to variations in Ca~(2+) concentration. The effects of exogenous NO donator on tonoplast proton pumps depended on the concentration of Ca~(2+), which apparently can mediate NO action.