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Systemic Signaling of the Plant Nitrogen Status Triggers Specific Transcriptome Responses Depending on the Nitrogen Source in Medicago truncatula.

Abstract : 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 NO(3)(-) uptake, NH(4)(+) uptake, and N(2) fixation are under general control by systemic signaling of plant N status. Indeed, irrespective of the nature of the N source, N acquisition by one side of the root system is repressed by high N supply to the other side. Transcriptome analysis facilitated the identification of over 3,000 genes that were regulated by systemic signaling of the plant N status. However, detailed scrutiny of the data revealed that the observation of differential gene expression was highly dependent on the N source. Localized N starvation results, in the unstarved roots of the same plant, in a strong compensatory up-regulation of NO(3)(-) uptake but not of either NH(4)(+) uptake or N(2) fixation. This indicates that the three N acquisition pathways do not always respond similarly to a change in plant N status. When taken together, these data indicate that although systemic signals of N status control root N acquisition, the regulatory gene networks targeted by these signals, as well as the functional response of the N acquisition systems, are predominantly determined by the nature of the N source.
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https://hal.archives-ouvertes.fr/hal-00275798
Déposant : Chantal Baracco <>
Soumis le : vendredi 25 avril 2008 - 12:27:36
Dernière modification le : vendredi 14 août 2020 - 17:26:04

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Sandrine Ruffel, Sandra Freixes, Sandrine Balzergue, Pascal Tillard, Christian Jeudy, et al.. Systemic Signaling of the Plant Nitrogen Status Triggers Specific Transcriptome Responses Depending on the Nitrogen Source in Medicago truncatula.. Plant Physiology, American Society of Plant Biologists, 2008, 146 (4), pp.2020-35. ⟨10.1104/pp.107.115667⟩. ⟨hal-00275798⟩

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