title: Mitochondrial respiratory pathways modulate nitrate sensing and nitrogen-dependent regulation of plant architecture in Nicotiana sylvestris.
abstract: Mitochondrial electron transport pathways exert effects on carbon-nitrogen (C/N) relationships. To examine whether mitochondria-N interactions also influence plant growth and development, we explored the responses of roots and shoots to external N supply in wild-type (WT) Nicotiana sylvestris and the cytoplasmic male sterile II (CMSII) mutant, which has a N-rich phenotype. Root architecture in N. sylvestris seedlings showed classic responses to nitrate and sucrose availability. In contrast, CMSII showed an altered 'nitrate-sensing' phenotype with decreased sensitivity to C and N metabolites. The WT growth phenotype was restored in CMSII seedling roots by high nitrate plus sugars and in shoots by gibberellic acid (GA). Genome-wide cDNA-amplified fragment length polymorphism (AFLP) analysis of leaves from mature plants revealed that only a small subset of transcripts was altered in CMSII. Tissue abscisic acid content was similar in CMSII and WT roots and shoots, and growth responses to zeatin were comparable. However, the abundance of key transcripts associated with GA synthesis was modified both by the availability of N and by the CMSII mutation. The CMSII mutant maintained a much higher shoot/root ratio at low N than WT, whereas no difference was observed at high N. Shoot/root ratios were strikingly correlated with root amines/nitrate ratios, values of <1 being characteristic of high N status. We propose a model in which the amine/nitrate ratio interacts with GA signalling and respiratory pathways to regulate the partitioning of biomass between shoots and roots.
authors.affiliation: Plant Science Department, Centre for Crop Genetic Improvement, Rothamsted Research, Harpenden, Hertfordshire AL52JQ, UK.
authors.forename: Till K
authors.initials: TK
authors.lastname: Pellny
authors.forename: Olivier
authors.initials: O
authors.lastname: Van Aken
authors.forename: Christelle
authors.initials: C
authors.lastname: Dutilleul
authors.forename: Tonja
authors.initials: T
authors.lastname: Wolff
authors.forename: Karin
authors.initials: K
authors.lastname: Groten
authors.forename: Melike
authors.initials: M
authors.lastname: Bor
authors.forename: Rosine
authors.initials: R
authors.lastname: De Paepe
authors.forename: Agnès
authors.initials: A
authors.lastname: Reyss
authors.forename: Frank
authors.initials: F
authors.lastname: Van Breusegem
authors.forename: Graham
authors.initials: G
authors.lastname: Noctor
authors.forename: Christine H
authors.initials: CH
authors.lastname: Foyer
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D002244:Carbon / Q000378:metabolism; D016000:Cluster Analysis; D018744:DNA, Plant / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000254:growth & development / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D015026:Zeatin / Q000378:metabolism
chemical_list: D018744:DNA, Plant; D005875:Gibberellins; D009566:Nitrates; D010937:Plant Growth Regulators; D002244:Carbon; D015026:Zeatin; C007842:gibberellic acid; D009584:Nitrogen