title: Medicago truncatula increases its iron-uptake mechanisms in response to volatile organic compounds produced by Sinorhizobium meliloti.
abstract: Medicago truncatula represents a model plant species for understanding legume-bacteria interactions. M. truncatula roots form a specific root-nodule symbiosis with the nitrogen-fixing bacterium Sinorhizobium meliloti. Symbiotic nitrogen fixation generates high iron (Fe) demands for bacterial nitrogenase holoenzyme and plant leghemoglobin proteins. Leguminous plants acquire Fe via "Strategy I," which includes mechanisms such as rhizosphere acidification and enhanced ferric reductase activity. In the present work, we analyzed the effect of S. meliloti volatile organic compounds (VOCs) on the Fe-uptake mechanisms of M. truncatula seedlings under Fe-deficient and Fe-rich conditions. Axenic cultures showed that both plant and bacterium modified VOC synthesis in the presence of the respective symbiotic partner. Importantly, in both Fe-rich and -deficient experiments, bacterial VOCs increased the generation of plant biomass, rhizosphere acidification, ferric reductase activity, and chlorophyll content in plants. On the basis of our results, we propose that M. truncatula perceives its symbiont through VOC emissions, and in response, increases Fe-uptake mechanisms to facilitate symbiosis.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B5 Ciudad Universitaria, Morelia, Michoacán, Mexico, C.P. 58030.
authors.forename: Maria del Carmen
authors.initials: Mdel C
authors.lastname: Orozco-Mosqueda
authors.forename: Lourdes I
authors.initials: LI
authors.lastname: Macías-Rodríguez
authors.forename: Gustavo
authors.initials: G
authors.lastname: Santoyo
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Farías-Rodríguez
authors.forename: Eduardo
authors.initials: E
authors.lastname: Valencia-Cantero
mesh_terms: D018533:Biomass; D002734:Chlorophyll / Q000032:analysis; D038181:FMN Reductase / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism*; D046913:Medicago truncatula / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology*; D053204:Root Nodules, Plant / Q000382:microbiology; D016962:Sinorhizobium meliloti / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D012987:Soil; D055549:Volatile Organic Compounds; D002734:Chlorophyll; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase
references.citation: Arch Microbiol. 2007 May;187(5):351-60
references.pmid: 17180381
references.citation: Plant Physiol Biochem. 2008 Mar;46(3):371-9
references.pmid: 18321722
references.citation: Microbiol Mol Biol Rev. 2004 Jun;68(2):280-300
references.pmid: 15187185
references.citation: Plant Signal Behav. 2008 Apr;3(4):263-5
references.pmid: 19704649
references.citation: Phytochemistry. 2006 Oct;67(20):2262-8
references.pmid: 16949113
references.citation: Curr Biol. 2005 Mar 29;15(6):531-5
references.pmid: 15797021
references.citation: Proc Natl Acad Sci U S A. 2011 Apr 26;108(17):7253-8
references.pmid: 21482761
references.citation: Annu Rev Biochem. 1996;65:503-35
references.pmid: 8811188
references.citation: Plant Physiol Biochem. 2009 Nov-Dec;47(11-12):1082-8
references.pmid: 19716309
references.citation: Proc Natl Acad Sci U S A. 2003 Apr 15;100(8):4927-32
references.pmid: 12684534
references.citation: Nat Rev Microbiol. 2007 Aug;5(8):619-33
references.pmid: 17632573
references.citation: Plant J. 2009 May;58(4):568-77
references.pmid: 19154225
references.citation: Plant J. 2008 Aug;55(3):504-13
references.pmid: 18410479
references.citation: Mol Plant Microbe Interact. 2005 Dec;18(12):1269-76
references.pmid: 16478046
references.citation: PLoS One. 2011;6(11):e26114
references.pmid: 22087221
references.citation: Plant Signal Behav. 2012 Jan;7(1):79-85
references.pmid: 22301973