New Pantoea Strain as Antistress Agent and Growth Stimulator in Grain Growing

Oats (Avena sativa L.) is an important agricultural crop. Unfortunately, it is exposed to a wide range of phytopathogenic microorganisms that cause significant yield losses. Aa a result, agricultural science is on the outlook for new effective and sustainable pesticide methods. This research focused on a new bacterial strain of the Pantoea genus isolated from grain crops to assess its potential as an antagonist of phytopathogens and a plant growth stimulator. The strain was isolated from the Maruchak spring oats variety. The taxonomic identification relied on the 16S rRNA gene sequence. The antagonistic activity was assessed against the phytopathogens Fusarium graminearum F-877, Bipolaris sorokiniana F-529, Erwinia rhapontici B-9292, and Xanthomonas campestris B-4102. The ability of the strain to produce phytohormones and siderophores was determined spectrophotometrically. The biological nitrogen fixation was assessed using a Rapid N Cube nitrogen analyzer. A set of culture-dependent methods made it possible to measure the zinc, phosphorus, and potassium solubilization activity, as well as the biofilm-forming potential. The isolated strain was identified as Pantoea pleuroti. It exhibited antagonistic activity against the abovementioned phytopathogens. It was especially effective against F. graminearum F-877: the inhibition zone was 62 mm (agar block diffusion method) and 12 mm (agar well method). P. pleuroti produced such phytohormones as indole-3-acetic acid (5.64 mg/mL), gibberellic acid (284.3 μg/mL), and kinetin (9.46 μg/mL). In addition, it fixed atmospheric nitrogen (680.0 μg/mL), synthesized siderophores (53.1%), formed biofilms, and solubilized phosphates (102.3 μg/mL), potassium, and zinc. The obtained results confirmed the potential of P. pleuroti as part of biofertilizers, bioprotectors, and oat growth stimulators.