Oak (Quercus robur) Associated Endophytic Paenibacillus sp. Promotes Poplar (Populus spp.) Root Growth In Vitro.

Dorotėja Vaitiekūnaitė,Sigutė Kuusienė,Emilija Beniušytė

doi:10.3390/microorganisms9061151

Dorotėja Vaitiekūnaitė, Sigutė Kuusienė + Show 1 more

Open Access

https://doi.org/10.3390/microorganisms9061151

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Abstract

Soil fertilization is necessary for high-demand crop production in agriculture and forestry. Our current dependence on chemical fertilizers has significant harmful side effects. Biofertilization using microorganisms is a sustainable way to limit the need for chemical fertilizers in various enterprises. Most plant endophytic bacteria have thus far been unstudied for their plant growth promoting potential and hence present a novel niche for new biofertilizer strains. We isolated English oak (Quercus robur) endophytic bacteria and tested them for plant growth promoting traits (PGPTs) such as nitrogen fixation, phosphate mineralization/solubilization, siderophore and indole-3-acetic acid (IAA) production. We also investigated the effect the selected isolate had on poplar (Populus spp.) microshoot vegetative growth parameters in vitro. In total 48 bacterial strains were isolated, attributed to Bacillus, Delftia, Paenibacillus, Pantoea and Pseudomonas genera. All the isolates displayed at least three PGPTs, with 39.6% of the isolates displaying all five (all were Pseudomonas spp.) and 18.75% displaying four. Based on relative abundance, Paenibacillus sp. isolate was selected for the poplar microshoot inoculation study. The isolate had a significant positive effect on poplar microshoot root growth and development. Two tested poplar genotypes both had increased lateral root number and density, fresh and dry root biomass. Furthermore, one genotype had increased length and number of adventitious roots as well as a decrease in fresh aboveground biomass. The root enhancement was attributed to IAA production. We propose this isolate for further studies as a potential biofertilizer.

Highlights

Fertilization is a key aspect of continuous and efficient industrial production of various crop species in agriculture and forestry
The aim of this study was to investigate cultivable oak bacterial endophytes from oak phyllosphere and their plant growth promoting traits (PGPTs), as well as the effect selected bacteria may have on poplar (Populus spp.) microshoots in vitro for potential use as biofertilizers in future trials
In this study we assessed cultivable bacterial endophytes associated with English oak phyllosphere, their plant growth promoting traits and the effect selected isolate had on poplar microshoot vegetative growth parameters in vitro

Summary

Introduction

Fertilization is a key aspect of continuous and efficient industrial production of various crop species in agriculture and forestry. Microorganisms (usually bacteria or fungi) used as biofertilizers can enhance the nutritional status of their host plants through a variety of mechanisms, enhancing crop yields [2,5]. These beneficial microbes are an eco-friendly way to reduce and perhaps even eliminate the need for chemical fertilization [1,2,3,5,8,9,10]. Bacteria can produce plant growth regulators, such as indole3-acetic acid (IAA), which has been shown to positively affect plant growth and devel-

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