Table 3. Characterization of signaling molecules produced by potato soft-rot pathogens.
| Strains | AI-1 (NAHSL)*(ng/OD580) | AI-2# | Quinolones° | Auxins† (ng/OD580) | GABA§ | ||||||||
| 3-oxo-C6-HSL | 3-oxo-C8-HSL | 3-oxo-C10-HSL | C6-HSL | C8-HSL | Activity | HHQ | PQS | IAA | IPA | IBA | KA | ||
| Pectobacterium atrosepticum | |||||||||||||
| P. atrosepticum CFBP 1526T | 59±5 | 1475±125 | ≤5±2 | ≤5±2 | 67±10 | + | − | − | − | − | − | − | − |
| P. atrosepticum CFBP 6276 | 92±10 | 2300±250 | 10±3 | ≤5±2 | 100±14 | + | − | − | − | − | − | − | − |
| P. atrosepticum 100T | 26±6 | 650±100 | − | ≤5±2 | 34±4 | + | − | − | − | − | − | − | − |
| P. atrosepticum RNS 08.30.1A | 24±4 | 600±150 | − | ≤5±2 | 41±6 | + | − | − | − | − | − | − | − |
| Pectobacterium carotovorum | |||||||||||||
| P. carotovorum CFBP 2046T | 2500±125 | 100±5 | − | ≤5±2 | − | + | − | − | − | − | − | − | − |
| P. carotovorum EC153 | 25±4 | 625±100 | − | 36±3 | − | + | − | − | − | − | − | − | − |
| P. carotovorum 98.1 | 2225±200 | 89±8 | − | ≤5±2 | − | + | − | − | − | − | − | − | − |
| P. carotovorum RNS 08.42.1A | 950±225 | 38±9 | − | ≤5±2 | − | + | − | − | − | − | − | − | − |
| Dickeya spp. | |||||||||||||
| D. chrysanthemiCFBP 2048T | 950±75 | 23±3 | − | ≤5±2 | − | + | − | − | 11 990±1000 | − | 106±33 | 78±5 | − |
| D. dadantii3937 | 300±25 | 12±1 | − | ≤5±2 | − | + | − | − | 12 910±1440 | 364±71 | 78±7 | 54±20 | − |
| D. dianthicolaRNS 04.9 | 125±25 | 5±1 | − | ≤5±2 | − | + | − | − | 35 950±2350 | 22±10 | 90±30 | 67±20 | − |
| D. solaniRNS 08.23.3.1A | 50±5 | ≤5±2 | − | ≤5±2 | − | + | − | − | 876±190 | − | 82±2 | 66±10 | − |
Production of different N-acyl homoserine lactones (NAHSL) was determined by thin-layer chromatography (TLC) and HPLC-MS/MS. For quantification, NAHSL were extracted from PGA minimal medium culture at late exponential phase (optimal production).
Autoinducer-2 (AI-2) activity was determined using biosensor V. harveyi BB170.
Production of 4-hydroxy-2-heptylquinoline (HHQ) and Pseudomonas quinolone signal (PQS) were determined by TLC.
Production of indole-3-acetic acid (IAA), indole-3-propionic acid (IPA), indole-3-butyric acid (IBA) and kynurenic acid (KA) were determined by HPLC-UV. For quantification, indolic compounds were extracted from M9 minimal medium supplemented with l-tryptophan culture at stationary growth phase (optimal production).
Production of γ-amino butyric acid (GABA) was determined by ELISA test.(+) positive detection by the biosensor; (−) not detected or below threshold.