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High seed quality is a key trait to achieve successful crop establishment required for optimum yield and sustainable production. Seed storage conditions greatly impact two key seed quality traits; seed viability (ability to germinate and produce normal seedlings) and vigour (germination performance). Accumulated oxidative damage accompanies the loss of seed vigour and viability during ageing, indicating that redox control is key to longevity. Here, we studied the effects of controlled deterioration at 40°C and 75% relative humidity (RH) ('ageing') under two different O 2 concentrations (21 and 78% O 2 ) in Brassica oleracea Two B. oleracea genotypes with allelic differences at two QTLs that result in differences in abscisic acid (ABA) signalling and seed vigour were compared. Ageing led to a similar loss in germination speed in both genotypes that was lost faster under elevated O 2 In both genotypes, an equal oxidative shift in the glutathione redox state and a minor loss of α-tocopherol progressively occurred before seed viability was lost. In contrast, ABA levels were not affected by ageing. In conclusion, both ABA signalling and seed ageing impact seed vigour but not necessarily through the same biochemical mechanisms., (© 2019 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Fast and uniform germination is key to agricultural production and can be achieved by seed 'priming' techniques. Here, we characterised the responses of bread wheat ( Triticum aestivum L.) seeds to a hot steam treatment ('BioFlash'), which accelerated water uptake, resulting in faster germination and seedling growth, typical traits of primed seed. Before the completion of germination, metabolite profiling of seeds revealed advanced accumulation of several amino acids (especially cysteine and serine), sugars (ribose, glucose), and organic acids (glycerate, succinate) in hot steam-treated seeds, whereas sugar alcohols (e.g. arabitol, mannitol) and trehalose decreased in all seeds. Tocochromanols (the 'vitamin E family') rose independently of the hot steam treatment. We further assessed shifts in the half-cell reduction potentials of low-molecular-weight (LMW) thiol-disulfide redox couples [i.e. glutathione disulfide (GSSG)/glutathione (GSH) and cystine/cysteine], alongside the activities of the reactive oxygen species (ROS)-processing enzyme superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase. Upon the first 4 h of imbibition, a rapid conversion of LMW disulfides to thiols occurred. Completion of germination was associated with a re-oxidation of the LMW thiol-disulfide cellular redox environment, before more reducing conditions were re-established during seedling growth, accompanied by an increase in all ROS-processing enzyme activities. Furthermore, changes in the thiol-disulfide cellular redox state were associated to specific stages of wheat seed germination. In conclusion, the priming effect of the hot steam treatment advanced the onset of seed metabolism, including redox shifts associated with germination and seedling growth., (© 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Background and Aims: Loss of seed viability has been associated with deteriorative processes that are partly caused by oxidative damage. The breaking of dormancy, a seed trait that prevents germination in unfavourable seasons, has also been associated with oxidative processes. It is neither clear how much overlap exists between these mechanisms nor is the specific roles played by oxygen and reactive oxygen species., Methods: Antioxidant profiles were studied in fresh (dormant) or after-ripened (non-dormant) sunflower (Helianthus annuus) embryos subjected to controlled deterioration at 40 °C and 75 % relative humidity under ambient (21 %) or high O2 (75 %). Changes in seed vigour and viability, dormancy, protein carbonylation and fatty acid composition were also studied., Key Results: After-ripening of embryonic axes was accompanied by a shift in the thiol-based cellular redox environment towards more oxidizing conditions. Controlled deterioration under high O2 led to a faster loss of seed dormancy and significant decreases in glutathione reductase and glutathione peroxidase activities, but viability was lost at the same rate as under ambient O2. Irrespective of O2 concentration, the overall thiol-based cellular redox state increased significantly over 21 d of controlled deterioration to strongly oxidizing conditions and then plateaued, while viability continued to decrease. Viability loss was accompanied by a rapid decrease in glucose-6-phosphate-dehydrogenase, which provides NADPH for reductive processes such as required by glutathione reductase. Protein carbonylation, a marker of protein oxidation, increased strongly in deteriorating seeds. The lipid-soluble tocochromanols, dominated by α-tocopherol, and fatty acid profiles remained stable., Conclusions: After-ripening, dormancy-breaking during ageing and viability loss appeared to be associated with oxidative changes of the cytosolic environment and proteins in the embryonic axis rather than the lipid environment. High O2 concentrations accelerated dormancy alleviation but, surprisingly, did not accelerate the rate of viability loss., (© The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

During seed germination, the transition from a quiescent metabolic state in a dry mature seed to a proliferative metabolic state in a vigorous seedling is crucial for plant propagation as well as for optimizing crop yield. This work provides a detailed description of the dynamics of protein synthesis during the time course of germination, demonstrating that mRNA translation is both sequential and selective during this process. The complete inhibition of the germination process in the presence of the translation inhibitor cycloheximide established that mRNA translation is critical for Arabidopsis seed germination. However, the dynamics of protein turnover and the selectivity of protein synthesis (mRNA translation) during Arabidopsis seed germination have not been addressed yet. Based on our detailed knowledge of the Arabidopsis seed proteome, we have deepened our understanding of seed mRNA translation during germination by combining two-dimensional gel-based proteomics with dynamic radiolabeled proteomics using a radiolabeled amino acid precursor, namely [(35)S]-methionine, in order to highlight de novo protein synthesis, stability, and turnover. Our data confirm that during early imbibition, the Arabidopsis translatome keeps reflecting an embryonic maturation program until a certain developmental checkpoint. Furthermore, by dividing the seed germination time lapse into discrete time windows, we highlight precise and specific patterns of protein synthesis. These data refine and deepen our knowledge of the three classical phases of seed germination based on seed water uptake during imbibition and reveal that selective mRNA translation is a key feature of seed germination. Beyond the quantitative control of translational activity, both the selectivity of mRNA translation and protein turnover appear as specific regulatory systems, critical for timing the molecular events leading to successful germination and seedling establishment.

Despite having very similar initial pools of stored mRNAs and proteins in the dry state, mature Arabidopsis seeds can either proceed toward radicle protrusion or stay in a dormant state upon imbibition. Dormancy breaking, a prerequisite to germination completion, can be induced by different treatments though the underlying mechanisms remain elusive. Thus, we investigated the consequence of such treatments on the seed proteome. Two unrelated dormancy-releasing treatments were applied to dormant seeds, namely, cold stratification and exogenous nitrates, in combination with differential proteomic tools to highlight the specificities of the imbibed dormant state. The results reveal that both treatments lead to highly similar proteome adjustments. In the imbibed dormant state, enzymes involved in reserve mobilization are less accumulated and it appears that several energetically costly processes associated to seed germination and preparation for subsequent seedling establishment are repressed. Our data suggest that dormancy maintenance is associated to an abscisic-acid-dependent recapitulation of the late maturation program resulting in a higher potential to cope with environmental stresses. The comparison of the present results with previously published -omic data sets reinforces and extends the assumption that post-transcriptional, translational, and post-translational regulations are determinant for seed germination.

The seed is the dispersal unit of plants and must survive the vagaries of the environment. It is the object of intense genetic and genomic studies because processes related to seed quality affect crop yield and the seed itself provides food for humans and animals. Presently, the general aim of postgenomics analyses is to understand the complex biochemical and molecular processes underlying seed quality, longevity, dormancy, and vigor. Due to advances in functional genomics, the recent past years have seen a tremendous progress in our understanding of several aspects of seed development and germination. Here, we describe the proteomics protocols (from protein extraction to mass spectrometry) that can be used to investigate several aspects of seed physiology, including germination and its hormonal regulation, dormancy release, and seed longevity. These techniques can be applied to the study of both model plants (such as Arabidopsis) and crops.