• Processes allowing the recycling of organic nitrogen and export to young leaves seeds are important determinants plant yield, especially when plants nitrate-limited. Because autophagy is induced during leaf ageing in response starvation, its role remobilization was suspected. It recently shown that participates trafficking Rubisco-containing bodies vacuole. To investigate remobilization, several autophagy-defective (atg) Arabidopsis mutants were grown under low high nitrate supplies...

To investigate the lignification process and its physiological significance under drought-stressed conditions, changes in enzymes responsible for related parameters were determined white clover (Trifolium repens L.) leaves during 28 d of water deficit treatment. Water gradually decreased leaf potential (Psiw) to -2.33 MPa at day 28. For first 14 deficit, ascorbate peroxidase phenylalanine ammonia-lyase highly activated. Neither a change symptomatic oxidative stress nor growth inhibition was...

Glutamine synthetase (EC 6.3.1.2) is a key enzyme of ammonium assimilation and recycling in plants where it catalyses the synthesis glutamine from glutamate. In Arabidopsis, five GLN1 genes encode GS1 isoforms. GLN1;2 most highly expressed leaves over-expressed roots by supply rosettes ample nitrate compared with limiting supply. It shown here that promoter mainly active minor veins flowers and, to lower extent, parenchyma mature leaves. Cytoimmunochemistry reveals protein present companion...

The flow of 15N and 13C from storage compounds in organs remaining after defoliation (sources) to regrowing tissue (sinks), losses through root or shoot respiration were assessed by pulse-chase labeling during regrowth alfalfa (Medicago sativa L.) following removal. A total 73% labeled C 34% N mobilized source within 30 d. Although all the was recovered tissue, much lost, mainly as CO2 respired (61%) (8%), found a lesser extent sink (5%). After 3, 10, d regrowth, 87, 66, 52% N, respectively,...

The role of S in legume growth, N uptake, and N2 fixation was investigated using white clover (Trifolium repens L.) as a model species. We examined whether the effect sulphate addition on resulted from stimulation host plant specific nodulation, or nodule metabolism. Clones clover, inoculated with Rhizobium leguminosarum, were grown for 140 d hydroponic system three levels concentration (0 mM, 0.095 0.380 mM). Nodule morphological biochemical traits, such root length, biomass volume, protein...

Large amounts of nitrogen (N) fertilizers are used in the production oilseed rape. However, as low-input methods crop management introduced crops will need to withstand temporary N deficiency. In temperate areas, rape also be affected by frequent drought periods. Here we evaluated physiological and metabolic impact nitrate limitation on response water deprivation. Different fertilizer were applied plants at vegetative stage, which then deprived rehydrated. Both depletion accelerated leaf...

We investigated the function of ASN2, one three genes encoding asparagine synthetase (EC 6.3.5.4), which is most highly expressed in vegetative leaves Arabidopsis thaliana. Expression ASN2 and parallel higher content darkness suggest that leaf metabolism involves for synthesis. In asn2-1 knockout asn2-2 knockdown lines, disruption caused a defective growth phenotype ammonium accumulation. The asn2 mutant displayed depleted an accumulation alanine, GABA, pyruvate fumarate, indicating alanine...

Oilseed rape is the third largest oleaginous crop in world but requires high levels of N fertilizer which only 50% recovered seeds. This weak use efficiency associated with a low foliar remobilization, leading to significant return soil and risk pollution. Contrary what observed during senescence vegetative stages, remobilization from stems leaves considered efficient monocarpic senescence. However, contribution towards management cellular mechanisms involved remain largely unknown. To reach...

In coming decades, increasing temperatures are expected to impact crop yield and seed quality. To develop low input systems, the effects of temperature sulfur (S) nutrition in oilseed rape, a high S demanding crop, need be jointly considered. this study, we investigated [High Temperature (HT), 33°C/day, 19°C/night vs. Control (Ctrl T), 20°C/day, 15°C/day] supply (HS), 500 μm SO(2-) 4 Low (LS), 8.7 μM 4] during filling on (i) components [seed number, dry weight (SDW) yield], (ii) grain...

Abstract Background The decline in industrial emissions of sulphur (S) has led to a sulphate depletion soil resulting an alteration crop performance. In oilseed rape, S deficiency dramatically reduced the seed yield and/or quality. Paradoxically, little is known about impact limitation on rape leaf metabolism, despite it being key determinant growth. order identify metabolic processes involved response restriction, analysis young proteome combined with physiological study was carried out at...

To investigate the varietal difference in sulfur use efficiency (SUE) and drought stress tolerance, Brassica napus 'Mosa' 'Saturnin' were exposed to polyethylene glycol (PEG)-induced for 72 h. Direct quantification of S uptake, de novo synthesis amino acids proteins was performed by tracing 34S. The responses photosynthetic activity relation SUE also examined. total amount newly absorbed decreased with both cultivars but decrease rate significantly higher Mosa (-64%) than Saturnin (-41%)....

Autophagy is essential for protein degradation, nutrient recycling, and nitrogen remobilization. induced during leaf ageing in response to starvation, known play a fundamental role recycling remobilization seed filling. Accordingly, leaves of Arabidopsis autophagy mutants (atg) have been shown over-accumulate proteins peptides, possibly because reduced degradation capacity. Surprisingly, atg also displayed higher protease activities. The work reported here aimed at identifying the nature...

Glutamine synthetase (GS) is central for ammonium assimilation and consists of cytosolic (GS1) chloroplastic (GS2) isoenzymes. During plant ageing, GS2 protein decreases due to chloroplast degradation, GS1 activity increases support glutamine biosynthesis N remobilization from senescing leaves. The role the different Arabidopsis isoforms in nitrogen was examined using 15N tracing experiments. Only gln1;1-gln1;2-gln1;3 triple-mutation affecting three GLN1;1, GLN1;2, GLN1;3 genes significantly...

Abstract Our goal was to identify the leaf proteomic changes which appeared during N remobilisation that were associated or not with senescence of oilseed rape in response contrasting nitrate availability. Remobilisation and status followed using 15 tracing, patterns chlorophyll level, total protein content a molecular indicator based on expression senescence‐associated gene 12/ Cab genes. Three phases distinguished. Proteomics revealed 55 proteins involved metabolism, energy,...

Labeling 13CO2 in steady-state condition was used to estimate quantitative mobilization of recently fixed carbon or stored sugar during water-deficit white clover (Trifolium repens L.). Water-deficient gradually decreased leaf-water parameters and total amount carbon. Amount 13C incorporated into glucose, sucrose soluble sugars fraction rapidly after 3 days treatment. In contrast, the previously significantly increased 5 with a coincidence significant decrease starch concentration. A highly...

The aim of this study was to investigate the physiological significance increased proline loading phloem caused by water-deficit stress in relation nitrogen (N) uptake and assimilation. N assimilation were quantified 15N tracing well-watered (control) water deficit-stressed white clover (Trifolium repens). De novo synthesis also compared between treatments. relationships among concentrations exudates, uptake, newly absorbed assessed. synthesized exudates rapidly after 3 d deficit. treatment...

The impact of sulphur limitation on the remobilization endogenous S compounds during rosette stage oilseed rape, and interactions with N availability these processes, were examined using a long-term 34SO42− labelling method combined study leaf senescence progression (using SAG12/Cab as molecular indicator) gene expression transporters, BnSultr4;1 BnSultr4;2, involved in vacuolar sulphate efflux. After 51 d hydroponic culture at 0.3 mM (1 atom% excess), was stopped plants subject for 28 to...

How the remobilization of S and N reserves can meet needs seeds oilseed rape subject to limitation fertilization remains largely unclear. Thus, this survey aims determine incidence sulphate restriction [low (LS)] applied at bolting [growth stage (GS) 32], visible bud (GS 53), start pod filling 70) on source–sink relationships for N, dynamics endogenous/exogenous contributing seed yield quality. Sulphate restrictions GS 32, 53, 70 were annotated LS32, LS53, LS70. Long-term 34SO42− 15NO3−...

Phloem-derived amino acids are the major source of nitrogen supplied to developing seeds. Amino acid transfer from maternal filial tissue requires at least one cellular export step prior import into symplasmically isolated embryo. Some members UMAMIT (usually multiple move in an out transporter) family (UMAMIT11, 14, 18, 28, and 29) have previously been implicated this process. Here we show that additional family, UMAMIT24 UMAMIT25, also function Using a recently published yeast-based assay...

Although the impact of sulfur (S) availability on seed yield and nutritional quality seeds has been demonstrated, its coupled with nitrogen (N) remains poorly studied in oilseed rape. A deeper knowledge S N interactions components could improve fertilization management a sustainable manner. To address this question, our goals were to determine effects nine different strategies (i) interaction levels (ii) according timing application (by delaying fractionating inputs) agronomic performances...