Seed Longevity—The Evolution of Knowledge and a Conceptual Framework

Abstract

The lifespan or longevity of a seed is the time period over which it can remain viable. Seed longevity is a complex trait and varies greatly between species and even seed lots of the same species. Our scientific understanding of seed longevity has advanced from anecdotal ‘Thumb Rules,’ to empirically based models, biophysical explanations for why those models sometimes work or fail, and to the profound realisation that seeds are the model of the underexplored realm of biology when water is so limited that the cytoplasm solidifies. The environmental variables of moisture and temperature are essential factors that define survival or death, as well as the timescale to measure lifespan. There is an increasing understanding of how these factors induce cytoplasmic solidification and affect glassy properties. Cytoplasmic solidification slows down, 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 ability to germinate. This review captures the evolution of knowledge on seed longevity over the past five decades in relation to seed ageing mechanisms, technology development, including tools to predict seed storage behaviour and non-invasive techniques for seed longevity assessment. It is concluded that seed storage biology is a complex science covering seed physiology, biophysics, biochemistry and multi-omic technologies, and simultaneous knowledge advancement in these areas is necessary to improve seed storage efficacy for crops and wild species biodiversity conservation.

Insights into mechanisms of seed longevity in soybean: a review

“…These free radicals act as both initiators and terminators of lipid peroxidation process and once activated, these reactions continue auto catalytically causing structural and functional changes to the substrate (Ognjanovic et al, 2008). Enzymatic antioxidants like superoxide dismutase (SOD), catalases and peroxidases, and non-enzymatic antioxidants like ascorbic acid and glutathione control the levels of ROS wherein ascorbic acid content and activity typically decrease during seed maturation while glutathione plays a key role as redox buffer (Nadarajan et al, 2023). Thus reduced non-enzymatic antioxidant contents and catalase activity causes accumulation of ROS eventually leading to lipid peroxidation in soybean (Lin et al, 2022).…”

“…The cell wall organization, callose deposition in cell wall, cuticle development, cell wall modification, and secondary cell wall biogenesis are governed by Glyma.15G078300, Glyma.15G075300, Glyma.15G074700, Glyma.15G074000, and Glyma.15G072300 group of genes (Shao et al, 2007). The rate of oxygen consumption estimated through Q2 seed analyser is associated with germination capacity of seed and is affected by seed coat permeability and seed size besides dormancy status and imbibition rate (Nadarajan et al, 2023). Black seeded soybean with few pores on seed coat, high lignin content and narrow space between seed coat and cotyledon possesses greater longevity (Kuchlan et al, 2010).…”

“…Seed ageing is an inexorable and irreversible process influenced by both intrinsic and extrinsic factors and detected by cytological, physiological, biochemical and physical changes associated with decline in seed quality and viability (Nadarajan et al, 2023). Seed deterioration is considered to begin at physiological maturity (ie., pre-harvest) and continue during harvesting, processing and storage at a rate greatly influenced by genetic, production and environmental factors (Hampton and Tekrony, 1995).…”

The metabolic profiles of Eugenia astringens and E. uniflora (Myrtaceae) sensitive seeds affect desiccation

“…Some studies have been conducted to analyze metabolite profile variances among different morphotypes, germination phases and stress tolerance in DS seeds (Mazlan et al 2019, Qu et al 2019, L opez-Hidalgo et al 2021, Szuba et al 2022), but there is still a knowledge gap in the context of seed desiccation, especially in wild tropical DS-seeded species. What we do know is that the seed physiological behaviour of DS-seeded species can be affected by growth conditions and plant genotypes (Nadarajan et al, 2023). Moreover, most tropical DS seeds have only small traces of lipids, which might be oxidized under unfavourable conditions and lead to seed deterioration (Guimarães et al, 2020).…”

“…On the other hand, desiccation tolerant (DT) seeds resist dehydration below 0.1 g H 2 O g −1 DW without lethal damage (Leprince et al, 2017). A transition from fluid to extreme‐high‐viscosity liquid takes place in the cytoplasm of both DT‐ and DS‐seeded species alike, but the cellular composition influences the extent of cell shrinkage, which is a key factor for seed viability (Nadarajan et al, 2023). To achieve mechanical stabilization, complex storage reserves must be accumulated in the seed cells (Oliver et al, 2020).…”