Plant growth-promoting effects of native Pseudomonas strains on Mentha piperita (peppermint): an in vitro study

• Published in: Plant biology (Stuttgart, Germany) Vol. 17; no. 6; pp. 1218 - 1226
• Main Authors: Santoro, M. V., Cappellari, L. R., Giordano, W., Banchio, E.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-11-2015
• Subjects: Argentina; Aromatic plants; Endophytes - metabolism; essential oils; Indoleacetic Acids - metabolism; Mentha piperita; Mentha piperita - growth & development; Mentha piperita - metabolism; Monoterpenes - metabolism; native Pseudomonas; Oils, Volatile - metabolism; Phosphates - metabolism; Plant Development; Plant Structures - growth & development; Plant Structures - metabolism; Pseudomonas; Pseudomonas - metabolism; Pseudomonas putida; rhizobacteria; Rhizosphere; Siderophores - metabolism; Soil; Soil Microbiology; Species Specificity; volatile organic compounds; Mentha piperita; rhizobacteria; Aromatic plants; essential oils; volatile organic compounds; native Pseudomonas
• ISSN: 1435-8603; 1438-8677
• DOI: 10.1111/plb.12351

Plant growth-promoting rhizobacteria (PGPR) affect growth of host plants through various direct and indirect mechanisms. Three native PGPR (Pseudomonas putida) strains isolated from rhizospheric soil of a Mentha piperita (peppermint) crop field near Córdoba, Argentina, were characterised and screened in vitro for plant growth-promoting characteristics, such as indole-3-acetic acid (IAA) production, phosphate solubilisation and siderophore production, effects of direct inoculation on plant growth parameters (shoot fresh weight, root dry weight, leaf number, node number) and accumulation and composition of essential oils. Each of the three native strains was capable of phosphate solubilisation and IAA production. Only strain SJ04 produced siderophores. Plants directly inoculated with the native PGPR strains showed increased shoot fresh weight, glandular trichome number, ramification number and root dry weight in comparison with controls. The inoculated plants had increased essential oil yield (without alteration of essential oil composition) and biosynthesis of major essential oil components. Native strains of P. putida and other PGPR have clear potential as bio-inoculants for improving productivity of aromatic crop plants. There have been no comparative studies on the role of inoculation with native strains on plant growth and secondary metabolite production (specially monoterpenes). Native bacterial isolates are generally preferable for inoculation of crop plants because they are already adapted to the environment and have a competitive advantage over non-native strains.