Mechanisms of plant growth promotion of Pseudomonas chlororaphis PA23 and potential effects on soil microbial communities
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Date
2020-07
Authors
Wan, Joey
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Abstract
Plant growth-promoting bacteria (PGPB) are a heterogeneous group of soil microbes that confer beneficial effects to plants. Recent interest in sustainable and organic agriculture has highlighted the potential uses of PGPB as agricultural adjuncts. Currently, PGPB are used to increase crop yield and productivity. Substantial work has been done on the active metabolites secreted by PGPB that drive plant growth. However, little is known about their effects on the global transcriptome of the host plant. P. chlororaphis PA23 is a gram-negative bacterium that has shown great potential as a plant growth promoting agent. Using a combination of next-generation RNA sequencing and bioinformatic analyses, the mechanisms that underlie P. chlororaphis PA23 induced growth in Brassica napus seedlings were investigated. The results showed that P. chlororaphis modulates plant phytohormone signaling systems resulting in elevated expression levels of genes associated with photosynthesis and root hair development. Next, the scalability of P. chlororaphis PA23 as an agricultural adjunct with a Glycine max field study was investigated. An increase in soybean pod set following P. chlororaphis PA23 treatment was observed, suggesting plant growth-promoting activity under field conditions. To determine the effects of P. chlororaphis PA23 on the microbial communities found in the soil, a combination of marker-based sequencing and bioinformatic analyses were utilized. Here I report that the addition of P. chlororaphis PA23 does not alter the bacterial or fungal species diversity. Furthermore, I report that the community composition within the rhizosphere does not change in response to P. chlororaphis PA23. This research provides the necessary information for the development of P. chlororaphis PA23 as an agricultural adjunct and lays the foundation for multi-year field studies that integrate the utilization of P. chlororaphis PA23 as a PGPB.
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Keywords
Bioinformatics, Plant-Microbe Interactions, Biocontrol, Plant growth promotion, RNA sequencing, Microbiome