Stress and survival
The choice of ex situ conservation strategy depends on whether seeds are desiccation tolerant or sensitive. Up to 100,000 species may have seeds that are intolerant of drying. To develop a better estimate of the frequency of species with desiccation sensitive seeds, we are combining geographical information with analysis of seed traits such as mass, seed coat ratio, tolerance of drying, rate of drying, and embryo morphology.
For desiccation tolerant seeds that can be stored under seed bank conditions, the processes that lead to the gradual deterioration of collections are studied. Ageing in all organisms is associated with the accumulation of oxidative damage such as lipid peroxidation and protein and nucleic acid oxidation caused by reactive oxygen species. Our research is:
- investigating how cell death processes in seeds differ on a tissue-specific basis, and the role that programmed cell death plays in viability loss in ageing seeds.
- utilising omics-based approaches to provide a complete overview of the changes in gene expression, protein expression and metabolite levels that occur as seeds age, and to identify potential markers of seed viability.
- developing non-invasive techniques for screening seed collections to assess viability without the need for germination. For example, the volatile compounds released by seeds as they age can be detected using gas chromatography – mass spectroscopy, and this approach may offer a means of detecting the early signs of seed ageing enabling action to be taken before seeds start to die.
- testing the possibility that some cells remain viable in seeds that otherwise appear dead (unable to germinate), and that these cells could provide an opportunity to recover germplasm from non-viable seed collections.
*denotes Kew staff
- Colville*, L., Bradley, E.L., Lloyd, A.S., Pritchard*, H.W., Castle, L., Kranner*, I. (2012) Volatile fingerprints of seeds of four species indicate the involvement of alcoholic fermentation, lipid peroxidation, and Maillard reactions in seed deterioration during ageing and desiccation stress. Journal of Experimental Botany 63: 6519-6530.
- Gundel, P.E., Hamilton, C.E., Seal*, C.E., Helander, M., Martínez-Ghersa, M.A., Ghersa, C.M., Vázquez de Aldana, B.R., Zabalgogeazcoa, I., Saikkonen, K. (2012) Antioxidants in Festuca rubra L. seeds affected by the fungal symbiont Epichloë festucae. Symbiosis: 1-8.
- Hu, D., Ma, G., Wang, Q., Yao, J.H., Wang, Y., Pritchard*, H.W., Wang, X.F. (2012) Spatial and temporal nature of reactive oxygen species production and programmed cell death in elm (Ulmus pumila L.) seeds during controlled deterioration. Plant Cell and Environment 35: 2045-2059.
- Xia, K., Daws, M.I., Hay, F.R., Chen, W.Y., Zhou, Z.K., Pritchard*, H.W. (2012) A comparative study of desiccation responses of Asian Evergreen Oaks, Quercus subgenus Cyclobalanopsis and Quercus subgenus Quercus. South African Journal of Botany 78: 47-54.
- Zagorchev, L., Seal*, C.E., Kranner*, I., Odjakova, M. (2012) Redox state of low-molecular-weight thiols and disulphides during somatic embryogenesis of salt-treated suspension cultures of Dactylis glomerata L. Free Radical Research 46: 656-664.