Ultrastructural changes in Spirodela intermedia in response to osmotically-induced water shortage

The ultrastructural changes produced in the upper mesophyl cells of Spirodela intermedia W. Koch, by the inclusion of polyethylene glycol (PEG) in the nutrient solution, are related to the degree of the osmotically-induced water shortage. The ultrastructural characteristics of the -0.08 MPa treated fronds differed from the untreated ones in the form of the chloroplasts. PEG up to -0.20 MPa induced considerable cell structural disorganization as the swelling, breaking and disappearance of the outer membrane of the chloroplasts and the breakdown of the tonoplast into small vesicles.