what conditions might a plant encounter in the wild type tha

what conditions might a plant encounter in the wild type that would cause them to open or close stomata?

Solution

The opening and closing of stomata is regulated by the integration of environmental signals and endogenous hormonal stimuli.For plants that encounter dehydration stress,the most essential factor is the ability of stomata to close and thus prevent excess water loss.Opening and closing is achieved by the swelling and shrinking of the guard cells,which is driven by ion exchange;Cytoskeleton reorganization and metabolite production;the modulation of gene expression and the posttranslational modification of protein.Environmental factors such as CO2 concentration,biotic and abiotic stresses,and additionally different plant hormones,affect the stomas opening and closing.When the water level in the leaf drops below the critical point,the stoma closes in order to prevent the remaining water from evaporating.When the guard cells controlling the stoma absorb potassium ions,water enters the cells and causes them to swell and thus the stoma opens. When potassium leaves the cell,water again leaves the cell and the stoma closes.This system is regulated and directed by a hormone known as abscisic acid,depending on the level of water in the leaf.Stomatal closure is the earliest plant response to water deficit which is regulated by a complex network of signaling pathways.The complexity of the response is mainly dependent on the initial threshold of stress and individual plant’s stress history.Abscisic acid and Jasmonic Acid are positive regulators of stomatal closure,while auxin and cytokinins are positive regulators of stomatal opening.