RESUMO
Stomatal aperture changes modulate the rate of transpiration and gas exchange in plants. High cellular turgor of the guard cell pair due to water and solute influx leads to stomatal opening, whereas closing is caused by turgor reduction due to water and solute efflux. This process is controlled by plant hormones. We demonstrate that a vertebrate peptide hormone, the rat atrial natriuretic peptide (rANP), induces stomatal opening in Tradescantia sp. in a concentration dependent manner and provide evidence that rANP affects the amiloride sensitive Na+/H- channel. Furthermore, rANP was found to bind specifically to plant membranes isolated from leaf tissue. We propose that a plant natriuretic peptide (NP) analogue is part of a multifactorial control system that regulates transpiration and solute movements in plants.