Unexpectedly low nitrogen acquisition and absence of root architecture adaptation to nitrate supply in a Medicago truncatula highly branched root mutant

作者：Bourion Virginie^*; Martin Chantal; de Larambergue Henri; Jacquin Francoise; Aubert Gregoire; Martin Magniette Marie Laure; Balzergue Sandrine; Lescure Geoffroy; Citerne Sylvie; Lepetit Marc; Munier Jolain Nathalie; Salon Christophe; Duc Gerard

来源：Journal of Experimental Botany, 2014, 65(9): 2365-2380.

DOI：10.1093/jxb/eru124

• Amino acids
• highly branched root mutant
• Medicago truncatula
• nitrogen acquisition
• nitrogen limitation
• phenylpropanoid
• root architecture

To complement N-2 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.

• 出版日期2014-6