Short-term salinity and high temperature stress-associated ultrastructural alterations in young leaf cells of Oryza sativa L.

Abstract

Salinity and high temperature stresses adversely affect growth and development of rice plants. To investigate the response of rice cells to these stresses, we have analysed short-term stress-induced subcellular alterations in undifferentiated leaf cells of rice seedlings by transmission electron microscopy. Perturbations noted particularly with respect to plasma membrane, mitochondrial membranes, endoplasmic reticulum, polyribosomes and dictyosomes are highlighted. The subcellular changes evoked by both stresses after 4 h were lysis of the cytoplasm, accumulation of electron-dense granules in the cytoplasm, distension in the ER membranes, enhanced association of ribosomes with the endoplasmic reticulum, reduction in the number of mitochondrial cristae, as well as disorganization of cell wall fibrillar material. Certain changes were found to be unique to either the salinity or high temperature stress. Plasmolysis and increased cytoplasmic vesiculation were seen only in response to salinity stress, while discontinuity in the plasma membrane with close association of the osmiophilic granules were observed only in response to high temperature.