Indole 3 carboxylic acid

Indole-3-carboxylic acid (3ICA, 99%), indole-3-acetic acid (3IAA, 98%), indole-3-propionic acid (3IPA, 99%), indole-3-lactic acid (3ILA, 99%), 5-hydroxyindole-3-acetic acid (5HIAA, ≥98%), 2,3,4,5,6-D₅-benzoic acid (internal standard, D₅-BA, ≥99 atom % D, ≥99%), N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA, contains 1% trimethylchlorosilane, 99% BSTFA), N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA, >97%), formic acid (≥95%), hexane (≥97.0%), methanol (≥99.9%) were purchased from Sigma-Aldrich (Darmstadt, Germany); sulfuric acid, acetone, diethyl ether were Laboratory Reagent grade and obtained from Khimreactiv (Staryy Oskol, Russia).

All IAA derivatives used in this study (indole-3-acetic acid, 3-(2-hydroxyethyl)indole, ethyl-3-indole-acetate, 3-(3-hydroxypropyl)indole, 3-indoleacetonitrile, indole-3-acetamide, indole-3-butyric acid, DL-indole-3-lactic acid, indole-3-propionic acid, tryptamine, indole-3-acrycil acid and indole-3-carboxylic acid) and H₂¹⁸O were purchased from Sigma-Aldrich. All cloning and protein expression reagents were from ThermoFisher Scientific (Vilnius, Lithuania). All other reagents used in this study were of analytical or higher grade.
Caballeronia glathei strain DSM50014 was obtained from the German Collection of Microorganisms and Cell Cultures (DSMZ), Braunschweig, Germany. This strain was routinely cultivated in M1 medium (5 g L⁻¹ peptone, 3 g L⁻¹ meat extract, pH 7). For the IAA assimilation experiments, C. glathei DSM50014 was cultivated in M9 medium (3.5 g L⁻¹ Na₂HPO₄, 1.5 g L⁻¹ KH₂PO₄, 2.5 g L⁻¹ NaCl, 0.2 g L⁻¹ MgSO₄, 0.01 g L⁻¹ CaCl₂). Escherichia coli strains used in this study are listed in Supplementary Table S2. All E. coli strains were cultivated in LB medium. Ampicillin (50 μg mL⁻¹) and streptomycin (30 μg mL⁻¹) were added when necessary.

Tannic acid, trans-ferulic acid, indole-3-carboxylic acid and naringenin were purchased from Sigma-Aldrich. The effects of increasing concentrations of several metabolites on the hyphal growth of Fusarium graminearum were tested on potato dextrose agar (PDA) plates. Briefly, metabolites dissolved in various solvents (Tannic acid in water, trans-ferulic acid in ethanol, indole-3-carboxylic acid in ethanol, and naringenin in ethanol) were spread on PDA plates (25 mL media per plate) to obtain a final metabolite concentration of 0.01–10 mM. Equal volumes of water or ethanol were spread onto control plates according to the solvent used to dissolve the various metabolites. The plates were incubated for an hour to let the metabolites absorb into the media. A small plug of Fusarium graminearum Z-3639 was placed at the center of each plate and the plates were incubated under constant light at 27 °C for three days. The diameter of fungal colonies in each plate was measured and recorded each day after inoculation.