, Volume 221, Issue 2, pp 297–303 | Cite as

Nitric Oxide is Involved in the Azospirillum brasilense-induced Lateral Root Formation in Tomato

  • Cecilia M. Creus
  • Magdalena Graziano
  • Elda M. Casanovas
  • María A. Pereyra
  • Marcela Simontacchi
  • Susana Puntarulo
  • Carlos A. Barassi
  • Lorenzo Lamattina
Rapid Communication


Azospirillum spp. is a well known plant-growth-promoting rhizobacterium. Azospirillum-inoculated plants have shown to display enhanced lateral root and root hair development. These promoting effects have been attributed mainly to the production of hormone-like substances. Nitric oxide (NO) has recently been described to act as a signal molecule in the hormonal cascade leading to root formation. However, data on the possible role of NO in free-living diazotrophs associated to plant roots, is unavailable. In this work, NO production by Azospirillum brasilense Sp245 was detected by electron paramagnetic resonance (6.4 nmol. g−1 of bacteria) and confirmed by the NO-specific fluorescent probe 4,5-diaminofluorescein diacetate (DAF-2 DA). The observed green fluorescence was significantly diminished by the addition of the specific NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO). Azospirillum-inoculated and noninoculated tomato (Lycopersicon esculentum L.) roots were incubated with DAF-2 DA and examined by epifluorescence microscopy. Azospirillum-inoculated roots displayed higher fluorescence intensity which was located mainly at the vascular tissues and subepidermal cells of roots. The Azospirillum-mediated induction of lateral root formation (LRF) appears to be NO-dependent since it was completely blocked by treatment with cPTIO, whereas the addition of the NO donor sodium nitroprusside partially reverted the inhibitory effect of cPTIO. Overall, the results strongly support the participation of NO in the Azospirillum-promoted LRF in tomato seedlings.


Azospirillum Lateral roots Nitric oxide Tomato 



Agar Congo Red


adventitious root formation




4,5-diamino-fluorescein diacetate


electron paramagnetic resonance


indole acetic acid


N G -Nitro-L-arginine methyl ester hydrochloride


L-N5 -(1-iminoethyl)-ornithine dihydrochloride


lateral root


lateral root formation


nitric oxide




α-(p-chlorophenoxy) isobutyric acid


sterile distilled water


sodium nitroprusside



This work was supported by ANPCyT, CONICET, Fundación Antorchas and UNMdP, Argentina.


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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Cecilia M. Creus
    • 1
  • Magdalena Graziano
    • 2
  • Elda M. Casanovas
    • 1
  • María A. Pereyra
    • 1
  • Marcela Simontacchi
    • 3
  • Susana Puntarulo
    • 3
  • Carlos A. Barassi
    • 1
  • Lorenzo Lamattina
    • 2
  1. 1.Unidad Integrada Facultad de Cs. Agrarias (UNMdP) BalcarceArgentina
  2. 2.Instituto de Investigaciones BiológicasUNMdPMar del PlataArgentina
  3. 3.Fisicoquímica-PRALIB, Facultad de Farmacia y BioquímicaUBABuenos AiresArgentina

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