Introduction of a novel pathway for IAA biosynthesis to rhizobia alters vetch root nodule development

Serena Camerini, Beatrice Senatore, Enza Lonardo, Esther Imperlini, Carmen Bianco, Giancarlo Moschetti, Giuseppe L. Rotino, Bruno Campion, Roberto Defez

Research output: Contribution to journalArticlepeer-review


We introduced into Rhizobium leguminosarum bv. viciae LPR1105 a new pathway for the biosynthesis of the auxin, indole-3-acetic acid (IAA), under the control of a stationary phase-activated promoter active both in free-living bacteria and bacteroids. The newly introduced genes are the iaaM gene from Pseudomonas savastanoi and the tms2 gene from Agrobacterium tumefaciens. Free-living bacteria harbouring the promoter-iaaMtms2 construct release into the growth medium 14-fold more IAA than the wild-type parental strain. This IAA overproducing R. l. viciae, the RD20 strain, elicits the development of vetch root nodules containing up to 60-fold more IAA than nodules infected by the wild-type strain LPR1105. Vetch root nodules derived from RD20 are fewer in number per plant, heavier in terms of dry weight and show an enlarged and more active meristem. A significant increase in acetylene reduction activity was measured in nodules elicited in vetch by RD20.

Original languageEnglish
Pages (from-to)67-77
Number of pages11
JournalArchives of Microbiology
Issue number1
Publication statusPublished - Jul 2008


  • ARA
  • Auxin
  • IAA
  • Nitrogen fixation
  • Nodule zone
  • Vicia hirsuta

ASJC Scopus subject areas

  • Microbiology


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