Abstract
Plant growth–promoting rhizobacteria (PGPR) are beneficial microbes in the rhizosphere that can directly or indirectly stimulate plant growth. In addition, some can prime plants for enhanced defense against a broad range of pathogens and insect herbivores. In this study, four PGPR strains (Pseudomonas fluorescens N04, P. koreensis N19, Paenibacillus alvei T19, and Lysinibacillus sphaericus T22) were used to induce priming in Solanum lycopersicum (cv. Moneymaker) plants. Plants were inoculated with each of the four PGPRs, and plant tissues (roots, stems, and leaves) were harvested at 24 h and 48 h post-inoculation. Methanol-extracted metabolites were analyzed by ultra-high performance liquid chromatography mass spectrometry (UHPLC-MS). Chemometric methods were applied to mine the data and characterize the differential metabolic profiles induced by the PGPR. The results revealed that all four strains induced defense-related metabolic reprogramming in the plants, characterized by dynamic changes to the metabolomes involving hydroxycinnamates, benzoates, flavonoids, and glycoalkaloids. In addition, targeted analysis of aromatic amino acids indicated differential quantitative increases or decreases over a two-day period in response to the four PGPR strains. The metabolic alterations point to an altered or preconditioned state that renders the plants primed for enhanced defense responses. The results contribute to ongoing efforts in investigating and unraveling the biochemical processes that define the PGPR priming phenomenon.
Highlights
Agricultural food production is hampered by a plethora of plant pathogens and herbivores that lower crop yields [1,2,3]
Aromatic amino acids (Phe, Trp, and Tyr) were quantified using a multiple reaction monitoring (MRM) method established on a triple quadrupole mass spectrometer(QqQ-MS) instrument
The data obtained in this study evidenced that PGPR inoculation of tomato plants leads to strain-specific and time-dependent metabolic reprogramming
Summary
Agricultural food production is hampered by a plethora of plant pathogens and herbivores that lower crop yields [1,2,3]. There is a need for new environmentally friendly ways to minimize the negative effects of both pathogens and herbivores In this regard, the rhizosphere-inhabiting microorganisms are being investigated for improving plant health and growth without extensive use of agrochemicals [7,8,9,10]. The rhizosphere is the microscopic zone surrounding plant roots in which a complex relationship co-exists between a plant, soil microbes, and the soil itself This zone harbors both deleterious (pathogens) and beneficial organisms (symbiotic rhizobia, certain actinomycetes, mycorrhizal fungi, and free-living bacteria) that have either negative or positive effects on plant growth and production [7,11]. Plant growth–promoting rhizobacteria (PGPRs) are free-living bacteria inhabiting
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
