Native bacteria isolated from roots and rhizosphere of Solanum lycopersicum L. increase tomato seedling growth under a reduced fertilization regime

María Micaela Pérez-Rodriguez,Patricia Piccoli,María Soledad Anzuay,Miguel Andrés Lobato Ureche,Rita Baraldi,Ana Carmen Cohen,Tania Taurian,Diana María Segura,Luisa Neri

doi:10.1038/s41598-020-72507-4

Abstract

In semiarid regions is important to use native strains best adapted to these environments to optimize plant-PGPR interaction. We aimed to isolate and characterize PGPR from roots and rhizosphere of a tomato crop, as well as studying the effect of its inoculation on tomato seedlings growth. We selected four strains considering their effectiveness of fixing nitrogen, solubilizing phosphate, producing siderophores and indole acetic acid. They belong to the genera Enterobacter, Pseudomonas, Cellulosimicrobium, and Ochrobactrum. In addition, we also analyzed the ability to solubilize Ca3(PO4)2, FePO4 and AlPO4 and the presence of one of the genes encoding the cofactor PQQ in their genome. Enterobacter 64S1 and Pseudomonas 42P4 showed the highest phosphorus solubilizing activity and presence of pqqE gene. Furthermore, in a tomato-based bioassay in speed-bed demonstrated that a sole inoculation at seedling stage with the strains increased dry weight of roots (49–88%) and shoots (39–55%), stem height (8–13%) and diameter (5–8%) and leaf area (22–31%) and were equal or even higher than fertilization treatment. Leaf nitrogen and chlorophyll levels were also increased (50–80% and 26–33%) compared to control. These results suggest that Enterobacter 64S1 and Pseudomonas 42P4 can be used as bio-inoculant in order to realize a nutrient integrated management.

Highlights

In semiarid regions is important to use native strains best adapted to these environments to optimize plant-plant growth-promoting rhizobacteria (PGPR) interaction
The use of plant growth-promoting rhizobacteria (PGPR) in agriculture could be a sustainable and environmentally friendly solution reducing problems associated with the overuse of chemicals fertilizers[9]
The pyrroloquinoline quinone (PQQ) cofactor is necessary for the activity of glucose dehydrogenase (GDH) that catalyses the oxidation of glucose to gluconic acid

Summary

Introduction

In semiarid regions is important to use native strains best adapted to these environments to optimize plant-PGPR interaction. We selected four strains considering their effectiveness of fixing nitrogen, solubilizing phosphate, producing siderophores and indole acetic acid They belong to the genera Enterobacter, Pseudomonas, Cellulosimicrobium, and Ochrobactrum. The use of native soil bacterial isolates has the advantage of easier adaptation and success when inoculated into the plant rhizosphere[18] They are more resistant to local environmental stresses especially under the predicted climatic changes s cenarios[19,20,21]. The aim of this work was to isolate and characterize PGPR from roots and rhizosphere of tomato crops and to study the effect of their inoculation on the growth of tomato seedlings in order to reduce the fertilizer’s rates and produce high quality plantlets (with an increased root system) that are suitable for transplanting into the farm

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