Unexpectedly low nitrogen acquisition and absence of root architecture adaptation to nitrate supply in a Medicago truncatula highly branched root mutant.
To complement N2 fixation through symbiosis, legumes can efficiently acquire soil mineral N through adapted root architecture. However, root architecture adaptation to mineral N availability has been little studied in legumes. Therefore, this study investigated the effect of nitrate availability on root architecture in Medicago truncatula and assessed the N-uptake potential of a new highly branched root mutant, TR185. The effects of varying nitrate supply on both root architecture and N uptake were characterized in the mutant and in the wild type. Surprisingly, the root architecture of the mutant was not modified by variation in nitrate supply. Moreover, despite its highly branched root architecture, TR185 had a permanently N-starved phenotype. A transcriptome analysis was performed to identify genes differentially expressed between the two genotypes. This analysis revealed differential responses related to the nitrate acquisition pathway and confirmed that N starvation occurred in TR185. Changes in amino acid content and expression of genes involved in the phenylpropanoid pathway were associated with differences in root architecture between the mutant and the wild type.
INRA, UMR1347 Agroécologie, BP 86510, F-21065 Dijon, France virginie.bourion@dijon.inra.fr.
Virginie
V
Bourion
INRA, UMR1347 Agroécologie, BP 86510, F-21065 Dijon, France.
Chantal
C
Martin
INRA, UMR1347 Agroécologie, BP 86510, F-21065 Dijon, France.
Henri
H
de Larambergue
INRA, UMR1347 Agroécologie, BP 86510, F-21065 Dijon, France.
Françoise
F
Jacquin
INRA, UMR1347 Agroécologie, BP 86510, F-21065 Dijon, France.
Grégoire
G
Aubert
INRA, UMR518 MIA, F-75231 Paris, France AgroParisTech, UMR MIA, F-75231 Paris, France INRA, UMR1165 URGV, F-91057 Evry, France UEVE, UMR URGV, F-91057 Evry, France CNRS, ERL8196 UMR URGV, F-91057 Evry, France.
Marie-Laure
ML
Martin-Magniette
INRA, UMR1165 URGV, F-91057 Evry, France UEVE, UMR URGV, F-91057 Evry, France CNRS, ERL8196 UMR URGV, F-91057 Evry, France.
Sandrine
S
Balzergue
Institut Jean-Pierre Bourgin, UMR1318 INRA/AgroParisTech, F-78026 Versailles, France.
Geoffroy
G
Lescure
Institut Jean-Pierre Bourgin, UMR1318 INRA/AgroParisTech, F-78026 Versailles, France.
Sylvie
S
Citerne
USC1342 INRA, UMR113 IRD-CIRAD-SupAgro-UM2, Symbioses Tropicales et Méditerranéennes, Campus de Baillarguet, TA A-82/J, F-34398 Montpellier Cedex 5, France.
Marc
M
Lepetit
INRA, UMR1347 Agroécologie, BP 86510, F-21065 Dijon, France.
Nathalie
N
Munier-Jolain
INRA, UMR1347 Agroécologie, BP 86510, F-21065 Dijon, France.
Christophe
C
Salon
INRA, UMR1347 Agroécologie, BP 86510, F-21065 Dijon, France.
Gérard
G
Duc
D000596:Amino Acids / Q000378:metabolism; D046913:Medicago truncatula / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
D000596:Amino Acids; D009566:Nitrates; D010940:Plant Proteins; D009584:Nitrogen
Amino acids; Medicago truncatula; highly branched root mutant; nitrogen acquisition; nitrogen limitation; phenylpropanoid; root architecture.