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Pyoluteorin and 2,4-diacetylphloroglucinol are major contributors to Pseudomonas protegens Pf-5 biocontrol against Botrytis cinerea in cannabis
Pseudomonas protegens Pf-5 is an effective biocontrol agent that protects many crops against pathogens, including the fungal pathogen Botrytis cinerea causing gray mold disease in Cannabis sativa crops. Previous studies have demonstrated the important role of antibiotics pyoluteorin (PLT) and 2,4-di...
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Published in: | Frontiers in microbiology 2022-08, Vol.13, p.945498-945498 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Pseudomonas protegens
Pf-5 is an effective biocontrol agent that protects many crops against pathogens, including the fungal pathogen
Botrytis cinerea
causing gray mold disease in
Cannabis sativa
crops. Previous studies have demonstrated the important role of antibiotics pyoluteorin (PLT) and 2,4-diacetylphloroglucinol (DAPG) in Pf-5-mediated biocontrol. To assess the potential involvement of PLT and DAPG in the biocontrol exerted by Pf-5 against
B. cinerea
in the phyllosphere of
C. sativa
, two knockout Pf-5 mutants were generated by in-frame deletion of genes
pltD
or
phlA
, required for the synthesis of PLT or DAPG respectively, using a two-step allelic exchange method. Additionally, two complemented mutants were constructed by introducing a multicopy plasmid carrying the deleted gene into each deletion mutant.
In vitro
confrontation assays revealed that deletion mutant ∆
pltD
inhibited
B. cinerea
growth significantly less than wild-type Pf-5, supporting antifungal activity of PLT. However, deletion mutant ∆
phlA
inhibited mycelial growth significantly more than the wild-type, hypothetically due to a co-regulation of PLT and DAPG biosynthesis pathways. Both complemented mutants recovered
in vitro
inhibition levels similar to that of the wild-type. In subsequent growth chamber inoculation trials, characterization of gray mold disease symptoms on infected cannabis plants revealed that both ∆
pltD
and ∆
phlA
significantly lost a part of their biocontrol capabilities, achieving only 10 and 19% disease reduction respectively, compared to 40% achieved by inoculation with the wild-type. Finally, both complemented mutants recovered biocontrol capabilities
in planta
similar to that of the wild-type. These results indicate that intact biosynthesis pathways for production of PLT and DAPG are required for the optimal antagonistic activity of
P. protegens
Pf-5 against
B. cinerea
in the cannabis phyllosphere. |
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ISSN: | 1664-302X 1664-302X |
DOI: | 10.3389/fmicb.2022.945498 |