Changes in the ultrastructure of meristematic root cells of Allium sativum L. treated with selenium

Ultrastructure of meristematic cells of garlic (Allium sativum L.) roots treated with sodium selenate and sodium selenite was assessed using transmission electron microscopy. Both selenium compounds applied at the concentrations: 80, 160 and 320 mu M caused many malformations in the ultrastructure of mitochondria, plastids, endoplasmic reticulum and Golgi apparatus such as deformation in shape and size, disturbances in inner membranes organization, appearance of concentric or parallel arrangement of ER cisternae. Moreover, in the presence of selenium, beside uneven thickening of cell wall, many vacuoles of different dimensions filled with wall-like material even in the vicinity of nucleus were visible. The latter results suggest that selenium not only intensified the synthesis of cell wall material but also inhibited the process of cell wall material deposition. The similarity of all observed ultrastructural changes in garlic root cells after selenium treatment with those appearing after action of other stress factors are discussed.