The science of ageing

All living organisms eventually age and lose viability. The seeds of higher plants are no exception. Genes control why and how an organism ages. However, the precise mechanisms of ageing and cell death are still unclear. We use protocols of 'artificial ageing' that induce viability loss in seeds. Our studies aim at a better understanding of the underlying biochemical and biophysical aspects of ageing.

'Oxidative stress' can cause ageing. The culprits are 'free radicals'. These can attack important molecules such as DNA, RNA, proteins and lipids. In healthy cells, 'antioxidants' such as glutathione, ascorbate ('vitamin C') and tocopherol ('vitamin E') counteract free radicals. However, aged organisms have less antioxidants and free radicals take over. Using lipid and gas chromatography, we have found that ageing results in breakdown of seed antioxidants and lipids.

Figure 1 DNA Laddering

DNA is intact in viable seeds. Dead seeds show 'DNA laddering'. This is part of a program by which cells 'commit suicide', programmed cell death. In this way, DNA is cleaved into small fragments (Fig 1). First lane: 100-basepair marker; from left to right: viable to dead seeds.

Our studies will enhance the current knowledge of ageing phenomena. Secondly, we will develop new diagnostic markers of seed viability. Such markers allow for a rapid assessment of seed quality and are important for agricultural and conservation purposes.

Contact:  Fiona Hay

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