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Legumes can acquire nitrogen (N) from NO(3)(-), NH(4)(+), and N(2) (through symbiosis with Rhizobium bacteria); however, the mechanisms by which uptake and assimilation of these N forms are coordinately regulated to match the N demand of the plant are currently unknown. Here, we find by use of the split-root approach in Medicago truncatula plants that(More)
The relationships between symbiotic nitrogen fixation (SNF) activity and C fluxes were investigated in pea plants (Pisum sativum L. cv. Baccara) using simultaneous 13C and 15N labelling. Analysis of the dynamics of labelled CO2 efflux from the nodulated roots allowed the different components associated with SNF activity to be calculated, together with root(More)
Detailed information has arisen from research at gene and cell levels, but it is still incomplete in the context of a quantitative understanding of whole plant physiology. Because of their integrative nature, process-based simulation models can help to bridge the gap between genotype and phenotype and assist in deconvoluting genotype-by-environment (GxE)(More)
The effect of the nitrogen source (gaseous nitrogen, N2, or nitrate ions, NO3-) on the use of carbon (C) for root and nodule growth of pea (Pisum sativum L.) was investigated using 13C-labelling of assimilated CO2 at various stages of growth. Nitrate supply and growing conditions (sowing dates, air CO2 concentration) were varied to alter photosynthetic(More)
The effect of nitrogen source (N(2) or nitrate) on carbon assimilation by photosynthesis and on carbon partitioning between shoots and roots was investigated in pea (Pisum sativum L. 'Baccara') plants at different growth stages using (13)C labelling. Plants were grown in the greenhouse on different occasions in 1999 and 2000. Atmospheric [CO(2)] and growth(More)
BACKGROUNDS AND AIMS Nitrogen nutrition of legumes, which relies both on atmospheric N2 and soil mineral N, remains a major limiting factor of growth. A decade ago, breeders tried to increase N uptake through hypernodulation. Despite their high nodule biomass, hypernodulating mutants were never shown to accumulate more nitrogen than wild types; they even(More)
Reductions in sulfur dioxide emissions and the use of sulfur-free mineral fertilizers are decreasing soil sulfur levels and threaten the adequate fertilization of most crops. To provide knowledge regarding legume adaptation to sulfur restriction, we subjected Medicago truncatula, a model legume species, to sulfur deficiency at various developmental stages,(More)
The seed development and composition of Medicago truncatula Gaertn., the new model plant for grain legumes, was studied using nine genotypes of the species complex: M. truncatula-Medicago littoralis (M. truncatula). The seed development of M. truncatula was very similar to that of other legumes, the only notable exception being the presence, in the mature(More)
Adaptation of Medicago truncatula to local nitrogen (N) limitation was investigated to provide new insights into local and systemic N signaling. The split-root technique allowed a characterization of the local and systemic responses of NO(3)(-) or N(2)-fed plants to localized N limitation. (15)N and (13)C labeling were used to monitor plant nutrition.(More)
The fluxes of (1) exogenous nitrogen (N) assimilation and (2) remobilization of endogenous N from vegetative plant compartments were measured by 15N labeling during the seed-filling period in pea (Pisum sativum L. cv Cameor), to better understand the mechanism of N remobilization. While the majority (86%) of exogenous N was allocated to the vegetative(More)