Photo: Mari Tefre, Global Crop Diversity Trust
This is the entrance to the Svalbard Global Seed Vault (SGSV). The vault contains approximately 268,000 seed samples representing agriculture in 220 countries, held in trust for all humanity as a shield against catastrophe. The only reason the SGSV, the Millenium Seed Bank, and repositories like them around the world are possible is because the orthodox seeds  stored within them are capable of surviving at 5% moisture content. How is this anhydrobiosis possible?
Water is essential for life. Despite this apparent truism, there are organisms that have phases of their life cycle during which they can withstand dehydration to less than 5% water content on a fresh weight basis. This phenomenon has become known as “anhydrobiosis” or life without water. It is an attribute of many microorganisms [1, 2] including lichens, as well as such animals as tardigrades , bdelloid rotifers , members of the Artemiidae (cysts thereof) [7, 8], and some nematode species [9, 10]. In the kingdom Plantae, certain algae and mosses exhibit vegetative anhydrobiosis [7, 11] as do some ferns [12, 13] and those species constituting the so called “resurrection plants” . Orthodox seeds  are also capable of extreme dehydration allowing these seeds to remain viable in extremes of temperature [15, 16] and, in some instances, for over one thousand years [17, 18]. This trait has underpinned agriculture for millennia [19, 20], allowing a portion of each harvest to be withheld, dehydrated and hence, resistant to pathogen attack, to establish the next crop, either in the subsequent year or decades into the future. A group of intrinsically disordered, highly hydrophilic proteins, prevalent late during plant embryogenesis are thought to participate in all aspects of preparing the cell for the loss of water. These so called, Late Embryogenesis Abundant (LEA) proteins, which were first identified , and then named , from studies of cotton seed proteins found in the embryo, have subsequently been identified in a variety of organisms within and outside the plant kingdom in the ensuing 30 years [23, 24]. The prevalence of an intrinsically disordered structure and high hydrophilicity has implicated the LEA proteins, in a variety of ways, in the replacement of water (or in compensating for its loss) in dehydrating tissues [25, 26].
Research Programs Studying LEAs
Dorothea Bartels, The University of Bonn, Germany
Julia Buitink, Université ďAngers, France
Alejandra A. Covarrubias, Universidad Nacional Autónoma de México, México
Bruce Downie, University of Kentucky, Lexington, Kentucky, USA
Jill M. Farrant, University of Cape Town, South Africa
Steven C. Hand, Louisiana State University, Baton Rouge, Louisiana, USA
Pia Harryson, Stockholm University, Sweden
Henk W.M. Hilhorst, Wageningen University, The Netherlands.
Dirk K. Hincha, Max-Planck-Institut, Germany
Yue-ie C. Hsing, Academia Sinica, Taiwan.
Gilles Hunault, Université ďAngers, France
Emmanuel Jaspard, Université ďAngers, France
Karen Koster, The University of South Dakota, USA
Olivier Leprince, Université ďAngers, France
David Macherel, Université ďAngers, France
Michael Menze, University of Louisville, Louisville, Kentucky, USA
Christina Payne, University of Kentucky, Lexington, Kentucky, USA
Nicholas Provart, University of Toronto, Canada
Richard Strimbeck, Norwegian University of Science and Technology, Norway
Alan Tunnacliffe, University of Cambridge, United Kingdom
The Late Embryogenesis Abundant Protein database (LEAPdb) is curated by:
Emmanuel Jaspard, Institut de Recherche en Horticulture et Semences (IRHS), MitoStress team and Gilles Hunault, Université d'Angers, Laboratoire d'Hémodynamique, Interaction Fibrose et Invasivité tumorale hépatique.
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16. Ellis, R.H., T.D. Hong, and E.H. Roberts, A low-moisture-content limit to logarithmic relations between seed moisture content and longevity. Annals of Botany, 1988. 61(4): p. 405-408.
17. Shen-Miller, J., M.B. Mudgett, J.W. Schopf, S. Clarke, and R. Berger, Exceptional Seed Longevity and Robust Growth: Ancient Sacred Lotus from China. American Journal of Botany, 1995. 82(11): p. 1367-1380.
18. Sallon, S., E. Solowey, Y. Cohen, R. Korchinsky, M. Egli, I. Woodhatch, O. Simchoni, and M. Kislev, Germination, genetics, and growth of an ancient date seed. Science, 2008. 320(5882): p. 1464.
19. Barker, G., The Agricultural Revolution in Prehistory: Why Did Foragers Become Farmers?2006, Oxford: Oxford University Press. 598.
20. Li, D.Z. and H.W. Pritchard, The science and economics of ex situ plant conservation. Trends Plant Sci, 2009. 14(11): p. 614-21.
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22. Galau, G.A., D.W. Hughes, and L.I. Dure, Developmental biochemistry of cottonseed embryogenesis and germination: changing messenger ribonucleic acid populations as shown by reciprocal heterologous complementary deoxyribonucleic acid-messenger ribonucleic acid hybridizationembryogenesis-abundant (Lea) mRNAs. . Plant Mol Biol 1986. 7: p. 155–170.
23. Garay-Arroyo, A., J.M. Colmenero-Flores, A. Garciarrubio, and A.A. Covarrubias, Highly hydrophilic proteins in prokaryotes and eukaryotes are common during conditions of water deficit. J Biol Chem, 2000. 275(8): p. 5668-74.
24. Wise, M.J., LEAping to conclusions: A computational reanalysis of late embryogenesis abundant proteins and their possible roles. Bmc Bioinformatics, 2003. 4.
25. Mouillon, J.M., P. Gustafsson, and P. Harryson, Structural investigation of disordered stress proteins. Comparison of full-length dehydrins with isolated peptides of their conserved segments. Plant Physiology, 2006. 141(2): p. 638-650.
26. Hand, S.C., M.A. Menze, M. Toner, L. Boswell, and D. Moore, LEA proteins during water stress: not just for plants anymore. Annu Rev Physiol, 2011. 73: p. 115-34.