Chilling temperature remodels phospholipidome of Zea mays seeds during imbibition - Biologie des semences
Article Dans Une Revue Scientific Reports Année : 2017

Chilling temperature remodels phospholipidome of Zea mays seeds during imbibition

Résumé

Global warming is a major agricultural issue in the Northern hemisphere where higher temperatures are expected to be associated with restricted water availability. In Europe, for maize, earlier and further northward sowings are forecasted in order to avoid water deficit periods in the crop life cycle. However these conditions may compromise seed germination and stand establishment since they will take place at cold temperatures. It is urgent to better understand the molecular bases of response of germinating maize seeds to cold in order to design genotypes adapted to these novel agricultural practices. Here we have performed a global phospholipidomic study to profile changes in membrane reorganisation during seed imbibition at 10 °C of cold-tolerant and-sensitive maize hybrids. Using a Multiple Reaction Monitoring (MRM-MS/MS) method coupled with HPLC we have identified 80 distinct phospholipids. We show that seed sensitivity to cold temperatures during imbibition relies on the accumulation of saturated or poorly unsaturated fatty acids, whatever the phospholipid class. In contrast seeds of cold-tolerant hybrid accumulated polyunsaturated chains which was associated with lower electrolyte leakage during imbibition at 10 °C. The expression of fatty acid desaturase genes provides a molecular model of maize seed sensitivity to imbibitional chilling damage. In Europe maize is the second major crop and it represents almost a quarter of the total cereal production 1. South France, Italy, Hungary and Romania are the main areas for maize production thus forming a geographic belt where the environmental conditions are optimum for growth and development of this crop. Studies on climate change performed in the last decade show consistent projections of increases in temperatures and changes in precipitation patterns at the global scale 2. In temperate areas, warming is predicted to increase by 2 °C in 2030 and water stress will dramatically increase in the southern regions of Europe. Both phenomena are expected to greatly reduce maize crop yields especially because they will affect the phenological stages of flowering and grain maturation 3, 4. Therefore novel agricultural practices must be designed in order to counteract the negative impacts of climate change, while taking advantage of its positive effects. Creation of stress tolerant hybrids and modification of sowing dates, with the use of early maturing hybrids, are short terms options which are already implemented 5. In addition, land reallocation is a long-term adaptation which is more and more discussed 6, 7. Indeed, in Europe, a northern shift of maize production area would allow to prevent more adverse conditions and would permit maize crops not to suffer from water deficit during the critical steps of growing 8, 9. Although attractive, this strategy will however lead maize seeds to germinate and maize seedlings to grow in inappropriate thermal conditions encountered at the time of stand establishment in European northern regions. Maize is indeed naturally adapted to environmental conditions of tropical regions 5 and the base temperature (Tb) commonly used for this plant is 10 °C 10 , indicating that a temperature of 10 °C can be defined as " low " or " cold " for this species, as this is stated in this work. In consequence cooler temperatures of European northern areas are expected to greatly affect seed germination and seedling establishment of maize which could in consequence prevent the successful use of reallocation strategies. Seed germination is a complex and tightly regulated process which starts with water absorption by the dry seed and ends when radicle elongates 11. Its achievement requires a synchronized achievement of many cellular processes including DNA repair, protein synthesis or membrane reorganization 11, 12. In dry seeds membranes are in a gel state and if water enters the seed before their transition to a liquid crystalline state leakage and damage.
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hal-01580388 , version 1 (01-09-2017)

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Agathe Noblet, Juliette Leymarie, Christophe Bailly. Chilling temperature remodels phospholipidome of Zea mays seeds during imbibition. Scientific Reports, 2017, 7 (1), pp.8886. ⟨10.1038/s41598-017-08904-z⟩. ⟨hal-01580388⟩
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