Non-thermal DBD plasma array on seed germination of different plant species

International audienceA dielectric barrier discharge (DBD) reactor producing cold plasma at atmospheric pressure has been used to treat seeds of eight different species and investigate their responses in term of germination. The device is made of nine cylindrical DBDs organized in a array and partially immersed in water. O2, N2, and air were flown in the device; the cold plasma from such gas is formed in the bubbles and touch liquid surface. Seeds were either located inside the water during plasma treatment process (direct treatment) or were watered by the water exposed to cold plasma beforehand (indirect treatment). Such plasma activated water contains reactive oxygen species and reactive nitrogen species. The statistical analysis shows that the probability of germinating of treated mung bean, mustard and radish is significantly higher than in control groups (p&#8201;&#8201;<&#8201;&#8201;0.05) for indirect treatments. A comparison of different treatment modalities (direct versus indirect treatment and gas composition) on germination boost has been completed on mung bean seeds. It is shown that direct plasma treatment using different gas (O2, N2, and air) give a strong enhancement of the mung bean germination probability compared to the control group; in the case of indirect treatment, only plasma air-treated water lead to a significant germination boost compared to the control group; this effect is still smaller than the one obtained using a direct treatment

Multi-omics analysis of abscisic acid roles in the control of Arabidopsis seed dormancy

International audienceAbscisic acid (ABA) is a key hormone in seed development and germination as well as adaptive responses to environmental stresses. The tissue-specific modulation of its endogenous levels by fine-tuning of synthesis and catabolism determines its physiological action. ABA is derived from cleavage of carotenoid precursors, which is a key regulatory step of the biosynthesis pathway. In Arabidopsis, the 9-cis epoxycarotenoid dioxygenase (NCED) that cleaves the cis-isomers of violaxanthin and neoxanthin is encoded by a multigene family. ABA inactivation occurs either by oxidation or conjugation and the major route is 8' hydroxylation by the CYP707A subfamily of P450 monooxygenases. A multi-omics analysis was performed on seeds of nced and cyp707a multiple mutants, which respectively exhibit reduced or increased seed dormancy, compared to wild type, in good correlation with their seed ABA contents. Hormone profiles in developing seeds revealed specific contributions of the different seed compartments to ABA production. Combined transcriptomic, proteomic and metabolomic data in wild type and mutant seeds highlighted important biological pathways that were differentially regulated by ABA levels, giving insights into a potential link with dormancy induction

Corrigendum to "Integrating proteomics and enzymatic profiling to decipher seed metabolism affected by temperature in seed dormancy and germination" [Plant Sci. 269 (2018) 118-125]

Temperature is an important environmental factor affecting seed dormancy and germination. The mechanism by which temperature induces germination in dormant seeds is however still unclear. Proteomic study has been performed in dormant sunflower seeds during imbibition at permissive and non-permissive temperatures for germination, 20 and 10 °C, respectively. Proteome analysis showed an increase of proteins belonging to metabolism and energy from the first hours of imbibition followed by a decrease of proteins involved in protein metabolism and seed storage in germinating compared to non-germinating seeds. Proteomic study was completed by polysome and proteasome activity assessment and enzymatic profiling on several altered proteins involved in metabolism and energy. Results showed that 20 °C treatment induced the activation of both protein synthesis and degradation processes, the latter being related to proteasome activity during the germination sensu stricto, and to other degradation processes such as proteases during the post-germination. Interestingly, enzymatic profiles showed that TCA cycle and glycolysis were more active in non-germinating seeds in the phase I of the germination sensu stricto. This result suggests the regulation of central metabolism activity in germinating seeds. The control of energy production during imbibition seems to be involved in molecular networks controlling seed dormancy and germination

Integrating proteomics and enzymatic profiling to decipher seed metabolism affected by temperature in seed dormancy and germination.

Temperature is an important environmental factor affecting seed dormancy and germination. The mechanism by which temperature induces germination in dormant seeds is however still unclear. Proteomic study has been performed in dormant sunflower seeds during imbibition at permissive and non-permissive temperatures for germination, 20 and 10 °C, respectively. Proteome analysis showed an increase of proteins belonging to metabolism and energy from the first hours of imbibition followed by a decrease of proteins involved in protein metabolism and seed storage in germinating compared to non-germinating seeds. Proteomic study was completed by polysome and proteasome activity assessment and enzymatic profiling on several altered proteins involved in metabolism and energy. Results showed that 20 °C treatment induced the activation of both protein synthesis and degradation processes, the latter being related to proteasome activity during the germination sensu stricto, and to other degradation processes such as proteases during the post-germination. Interestingly, enzymatic profiles showed that TCA cycle and glycolysis were more active in non-germinating seeds in the phase I of the germination sensu stricto. This result suggests the regulation of central metabolism activity in germinating seeds. The control of energy production during imbibition seems to be involved in molecular networks controlling seed dormancy and germination

Integrating proteomics and enzymatic profiling to decipher seed metabolism affected by temperature in seed dormancy and germination.

Temperature is an important environmental factor affecting seed dormancy and germination. The mechanism by which temperature induces germination in dormant seeds is however still unclear. Proteomic study has been performed in dormant sunflower seeds during imbibition at permissive and non-permissive temperatures for germination, 20 and 10 °C, respectively. Proteome analysis showed an increase of proteins belonging to metabolism and energy from the first hours of imbibition followed by a decrease of proteins involved in protein metabolism and seed storage in germinating compared to non-germinating seeds. Proteomic study was completed by polysome and proteasome activity assessment and enzymatic profiling on several altered proteins involved in metabolism and energy. Results showed that 20 °C treatment induced the activation of both protein synthesis and degradation processes, the latter being related to proteasome activity during the germination sensu stricto, and to other degradation processes such as proteases during the post-germination. Interestingly, enzymatic profiles showed that TCA cycle and glycolysis were more active in non-germinating seeds in the phase I of the germination sensu stricto. This result suggests the regulation of central metabolism activity in germinating seeds. The control of energy production during imbibition seems to be involved in molecular networks controlling seed dormancy and germination

NADP-MALIC ENZYME 1 Affects Germination after Seed Storage in Arabidopsis thaliana

Aging decreases the quality of seeds and results in agricultural and economic losses. The damage that occurs at the biochemical level can alter the seed physiological status. Although loss of viability has been investigated frequently, little information exists on the molecular and biochemical factors involved in seed deterioration and loss of viability. Oxidative stress has been implicated as a major contributor to seed deterioration, and several pathways are involved in protection against this. In this study, we show that seeds of Arabidopsis thaliana lacking a functional NADP-MALIC ENZYME 1 (NADP-ME1) have reduced seed viability relative to the wild type. Seeds of the NADP-ME1 loss-of-function mutant display higher levels of protein carbonylation than those of the wild type. NADP-ME1 catalyzes the oxidative decarboxylation of malate to pyruvate with the simultaneous production of CO2 and NADPH. Upon seed imbibition, malate and amino acids accumulate in embryos of aged seeds of the NADP-ME1 loss-of-function mutant compared with those of the wild type. NADP-ME1 expression is increased in imbibed aged as compared with non-aged seeds. NADP-ME1 activity at testa rupture promotes normal germination of aged seeds. In seedlings of aged seeds, NADP-ME1 is specifically active in the root meristematic zone. We propose that NADP-ME1 activity is required for protecting seeds against oxidation during seed dry storage

Impacts of drought and elevated temperature on the seeds of malting barley

High seed quality is key to agricultural production, which is increasingly affected by climate change. We studied the effects of drought and elevated temperature during seed production on key seed quality traits of two genotypes of malting barley (Hordeum sativum L.). Plants of a “Hana-type” landrace (B1) were taller, flowered earlier and produced heavier, larger and more vigorous seeds that resisted ageing longer compared to a semi-dwarf breeding line (B2). Accordingly, a NAC domain-containing transcription factor (TF) associated with rapid response to environmental stimuli, and the TF ABI5, a key regulator of seed dormancy and vigour, were more abundant in B1 seeds. Drought significantly reduced seed yield in both genotypes, and elevated temperature reduced seed size. Genotype B2 showed partial thermodormancy that was alleviated by drought and elevated temperature. Metabolite profiling revealed clear differences between the embryos of B1 and B2. Drought, but not elevated temperature, affected the metabolism of amino acids, organic acids, osmolytes and nitrogen assimilation, in the seeds of both genotypes. Our study may support future breeding efforts to produce new lodging and drought resistant malting barleys without trade-offs that can occur in semi-dwarf varieties such as lower stress resistance and higher dormancy

The <em>Amborella</em> Genome and the Evolution of Flowering Plants

Amborella trichopoda is strongly supported as the single living species of the sister lineage to all other extant flowering plants, providing a unique reference for inferring the genome content and structure of the most recent common ancestor (MRCA) of living angiosperms. Sequencing the Amborella genome, we identified an ancient genome duplication predating angiosperm diversification, without evidence of subsequent, lineage-specific genome duplications. Comparisons between Amborella and other angiosperms facilitated reconstruction of the ancestral angiosperm gene content and gene order in the MRCA of core eudicots. We identify new gene families, gene duplications, and floral protein-protein interactions that first appeared in the ancestral angiosperm. Transposable elements in Amborella are ancient and highly divergent, with no recent transposon radiations. Population genomic analysis across Amborella's native range in New Caledonia reveals a recent genetic bottleneck and geographic structure with conservation implications