Behaviour of Aleurone Cells of Wild Oats (Avena fatua L.) — A Light Microscopic Study

Abstract

The aleurone layer isolated from the mature caryopses of wild oats ( Avena fatua L.) was studied with the light microscope, with particular reference to changes resulting from desiccation and imbibition. The aleurone cells on drying produced characteristic spiny vesicles or rays, which extended within the cell from the protoplast to the thin cell wall. They showed on hydrating thickened cell walls and slightly swollen protoplasts. The spiny vesicles observed in dry cells were not seen on hydration. Cells treated with NaOH showed neither the development of spiny vesicles on drying nor the thickening of cell walls on hydrating. The changes in protoplast and cell wall dimensions showed that the maximum enlargement of protoplasts in alkali-untreated cells due to hydration was prevented by the thickening of cell walls. The aleurone cell wall has neither pits nor plasmodesmata. It contains two components, the inner alkali-soluble and the rigid outer alkali-insoluble. The alkali-soluble component (hemicellulose) was needed for wall thickening on imbibition and the lack of it in the cell wall prevented the development of spiny vesicles from the protoplast in aleurone cells upon desiccation. The ability of cell walls to swell on hydrating and of protoplasts to produce spiny vesicles on drying might be significant in the long retention of germinability of wild oat caryopses.