Current Microbiology

, Volume 75, Issue 10, pp 1408–1418 | Cite as

Regulation of IAA Biosynthesis in Azospirillum brasilense Under Environmental Stress Conditions

  • Romina Molina
  • Diego Rivera
  • Verónica Mora
  • Gastón López
  • Susana Rosas
  • Stijn Spaepen
  • Jos Vanderleyden
  • Fabricio CassánEmail author


Indole-3-acetic acid (IAA) is one of the most important molecules produced by Azospirillum sp., given that it affects plant growth and development. Azospirillum brasilense strains Sp245 and Az39 (pFAJ64) were pre-incubated in MMAB medium plus 100 mg/mL l-tryptophan and treated with or exposed to the following (a) abiotic and (b) biotic stress effectors: (a) 100 mM NaCl or Na2SO4, 4.0% (w/v) PEG6000, 0.5 mM H2O2, 0.1 mM abscisic acid, 0.1 mM 1-aminocyclopropane 1-carboxylic acid, 45 °C or daylight, and (b) 4.0% (v/v) filtered supernatant of Pseudomonas savastanoi (Ps) or Fusarium oxysporum (Fo), 0.1 mM salicylic acid (SA), 0.1 mM methyl jasmonic acid (MeJA), and 0.01% (w/v) chitosan (CH). After 30 and 120 min of incubation, biomass production, cell viability, IAA concentration (µg/mL), and ipdC gene expression were measured. Our results show that IAA production increases with daylight or in the presence of PEG6000, ABA, SA, CH, and Fo. On the contrary, exposure to 45 °C or treatment with H2O2, NaCl, Na2SO4, ACC, MeJA, and Ps decrease IAA biosynthesis. In this report, growth and IAA biosynthesis in A. brasilense under biotic and abiotic stress conditions are discussed from the point of view of their role in bacterial lifestyle and their potential application as bioproducts.



We thank Universidad Nacional de Río Cuarto, Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Fondo Nacional de Ciencia y Tecnología (FONCyT), and Instituto Nacional de Tecnología Agropecuaria (INTA, Argentina). Fabricio Cassán, Veronica Mora, and Susana Rosas are researchers of CONICET at the UNRC. Romina Molina and Diego Rivera are PhD students at the UNRC with grants from CONICET.

Supplementary material

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Supplementary material 1 (DOCX 63 KB)
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Supplementary material 2 (DOCX 26 KB)


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Authors and Affiliations

  1. 1.Universidad Nacional de Río CuartoCórdobaArgentina
  2. 2.Katholieke Universiteit LeuvenLeuvenBelgium
  3. 3.Max Planck Institute for Plant Breeding Research, Plant Microbe InteractionsCologneGermany

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