Behaviour of Membranes and Proteins during Natural Seed Ageing

Abstract

Membrane integrity and protein secondary structure were studied in seeds of different plant species directly after harvest and after long-term storage in a seed bank. Electron paramagnetic resonance spin label studies revealed extensive membrane damage in the aged, nonviable seeds. In contrast, Fourier self-deconvolved infrared spectra of the proteins in these embryos did not reveal changes in relative peak height and band position of the different protein secondary structures with ageing. Extended beta-sheet structures typical of protein denaturation were also not observed. We conclude that in spite of the loss of membrane integrity with seed ageing the protein secondary structure in desiccation tolerant (orthodox) dry seeds is maintained during several decades of open storage.