AUTHOR=Świątczak Joanna , Kalwasińska Agnieszka , Brzezinska Maria Swiontek 

TITLE=Plant growth–promoting rhizobacteria: Peribacillus frigoritolerans 2RO30 and Pseudomonas sivasensis 2RO45 for their effect on canola growth under controlled as well as natural conditions

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1233237

DOI=10.3389/fpls.2023.1233237

ISSN=1664-462X

ABSTRACT=<p>Even though canola is one of the most important industrial crops worldwide, it has high nutrient requirements and is susceptible to pests and diseases. Therefore, natural methods are sought to support the development of these plants. One of those methods could be a plant growth–promoting rhizobacteria (PGPR) that have a beneficial effect on plant development. The aim of this study was a genomic comparison of two PGPR strains chosen based on their effect on canola growth: <italic>Peribacillus frigoritolerans</italic> 2RO30, which stimulated canola growth only in sterile conditions, and <italic>Pseudomonas sivasensis</italic> 2RO45, which promoted canola growth in both sterile and non-sterile conditions. First of all, six bacterial strains: RO33 (<italic>Pseudomonas</italic> sp.), RO37 (<italic>Pseudomonas poae</italic>), RO45 (<italic>Pseudomonas kairouanensis</italic>), 2RO30 (<italic>Peribacillus frigoritolerans</italic>), 2RO45 (<italic>Pseudomonas sivasensis</italic>), and 3RO30 (<italic>Pseudomonas migulae</italic>), demonstrating best PGP traits <italic>in vitro</italic>, were studied for their stimulating effect on canola growth under sterile conditions. <italic>P. frigoritolerans</italic> 2RO30 and <italic>P. sivasensis</italic> 2RO45 showed the best promoting effect, significantly improving chlorophyll content index (CCI) and roots length compared to the non-inoculated control and to other inoculated seedlings. Under non-sterile conditions, only <italic>P. sivasensis</italic> 2RO45 promoted the canola growth, significantly increasing CCI compared to the untreated control and to other inoculants. Genome comparison revealed that the genome of <italic>P. sivasensis</italic> 2RO45 was enriched with additional genes responsible for ACC deaminase (<italic>acdA</italic>), IAA (<italic>trpF</italic>, <italic>trpG</italic>), and siderophores production (<italic>fbpA</italic>, <italic>mbtH</italic>, and <italic>acrB</italic>) compared to 2RO30. Moreover, <italic>P. sivasensis</italic> 2RO45 showed antifungal effect against all the tested phytopathogens and harbored six more biosynthetic gene clusters (BGC), namely, syringomycin, pyoverdin, viscosin, arylpolyene, lankacidin C, and enterobactin, than <italic>P. frigoritolerans</italic> 2RO30. These BGCs are well known as antifungal agents; therefore, it can be assumed that these BGCs were responsible for the antifungal activity of <italic>P. sivasensis</italic> 2RO45 against all plant pathogens. This study is the first report describing <italic>P. sivasensis</italic> 2RO45 as a canola growth promoter, both under controlled and natural conditions, thus suggesting its application in improving canola yield, by improving nutrient availability, enhancing stress tolerance, and reducing environmental impact of farming practices.</p>