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

Abstract

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.

Beneficial rhizobacteria immobilized in nanofibers for potential application as soybean seed bioinoculants

“…However, longer roots and higher dry weight of roots was only evidenced in the soybean plants from the ISIB55-PVA and ISIB55-treated seeds (Fig 5B, 5C and 5D). It has been reported that native isolates are previously adapted to the local environment, which results in a competitive advantage over non-natives strains [70]. Thus, the present results suggest that P .…”

Microbe-based technology ameliorates glandular trichomes, secondary metabolites and antioxidants inPelargonium graveolensL'Hér.

“…In the present study the enhanced number of glandular trichomes in bioinoculant treatments in comparison with the control suggested the possible role of bioinoculants in stimulating the production of plant hormones. The greater number of glands may further be related to alterations in the principal aroma profile of the plants …”

“…The greater number of glands may further be related to alterations in the principal aroma profile of the plants. 26…”

Pseudomonas fluorescens LBUM677 differentially increases plant biomass, total oil content and lipid composition in three oilseed crops

“…Pseudomonas spp. beneficial effects on plant growth promotion have been associated with various mechanisms, including the production of antibiotics, the stimulation of plant defence systems through induced systemic resistance, the enhancement of plant nutrient uptake, the secretion of vitamins and siderophores, the synthesis of phytohormones and the production of 1‐aminocyclopropane‐1‐carboxylate (ACC) deaminase which degrades the ethylene precursor ACC (Parejko et al ; Ali et al ; Santoro et al ). Regardless of the mechanism(s) involved, the plant growth promotion effect due to Pseudomonas spp.…”

“…Significance and Impact of the Study: LBUM677 shows great potential to be used as an inoculum to promote oil yield and fatty acid accumulation in oilseed crops. Ali et al 2014;Santoro et al 2015). Regardless of the mechanism(s) involved, the plant growth promotion effect due to Pseudomonas spp.…”