Seed longevity-the evolution of knowledge and a conceptual framework

Authors: NADARAJAN, JAYANTHI - New Zealand Institute Of Plant & Food Research; Walters, Christina; PRITCHARD, HUGH - Royal Botanic Gardens, Kew; BALLESTEROS, DANIEL - University Of Valencia; COLVILLE, LOUISE - Royal Botanic Gardens, Kew

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2023
Publication Date: 1/19/2023
Citation: Nadarajan, J., Walters, C.T., Pritchard, H., Ballesteros, D., Colville, L.P. 2023. Seed longevity-the evolution of knowledge and a conceptual framework. Plants. 12(3). Article e471. https://doi.org/10.3390/plants12030471.
DOI: https://doi.org/10.3390/plants12030471

Interpretive Summary: This paper builds from the authors' research about seed storage categories and the interactions between water and temperature on seed storage behavior. In order to survive storage conditions, the cytoplasm within seeds must solidify into a glass. Orthodox and intermediate seeds survive this phase transition, though the latter continue to age rapidly. On the other hand, recalcitrant seeds do not. The thesis of the paper is that molecular crowding resulting from glass formation causes extreme mechanical damage in recalcitrant seeds and so they die almost immediately. In orthodox seeds, molecular crowding puts molecules into close proximity so that they eventually react and these slow reactions are the basis of aging during storage.

Technical Abstract: Plant genetic resources are a global necessity, either to implement Green Revolution promises of higher crop yields or to stave off increasing endangerment of plant populations brought on by social pressures or changing climate. Seed storage is the most efficient approach to ensuring availability of plant genetic resources, and the last fifty years has seen the basic question -- how long can seeds live? – rising in importance to meet demand in both agriculture and conservation. The science has advanced from anecdotal ‘Thumb Rules,’ to empirically-based models, to biophysical explanations for why those models sometimes work or fail, to the profound realization that seeds are an entrée to the unexplored realm of biology when water is so limited that cytoplasm solidifies. Environmental variables of moisture and temperature are essential factors that define survival or death as well as the time scale to measure life span. There is increasing understanding of how these factors induce cytoplasmic solidification and affect glassy properties. Cytoplasmic solidification slows, but does not stop, the chemical reactions involved in ageing. Continued degradation of proteins, lipids and nucleic acids damage cell constituents and reduce the seed’s metabolic capacity, eventually impairing the capacity to germinate. Frontiers in seed storage research aim to identify, prevent or ameliorate the lethal effects of storage.