제목 | Anti-Oomycete Activity and Pepper Root Colonization of Pseudomonas plecoglossicida YJR13 and Pseudomonas putida YJR92 against Phytophthora capsici |
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Previously, Pseudomonas plecoglossicida YJR13 and
Pseudomonas putida YJR92 from a sequential screening procedure were proven to effectively control Phytophthora blight caused by Phytophthora capsici. In this
study, we further investigated the anti-oomycete activities of these strains against mycelial growth, zoospore
germination, and germ tube elongation of P. capsici. We
also investigated root colonization ability of the bacterial strains in square dishes, including cell motility (swimming and swarming motilities) and biofilm formation.
Both strains significantly inhibited mycelial growth in
liquid and solid V8 juice media and M9 minimal media,
zoospore germination, and germ tube elongation compared with Bacillus vallismortis EXTN-1 (positive biocontrol strain), Sphingomonas aquatilis KU408 (negative
biocontrol strain), and MgSO4 solution (untreated control). In diluted (nutrient-deficient) V8 juice broth, the
tested strain populations were maintained at >108
cells/
ml, simultaneously providing mycelial inhibitory activity. Additionally, these strains colonized pepper roots at
a 106
cells/ml concentration for 7 days. The root colonization of the strains was supported by strong swimming
and swarming activities, biofilm formation, and chemotactic activity towards exudate components (amino
acids, organic acids, and sugars) of pepper roots. Collectively, these results suggest that strains YJR13 and
YJR92 can effectively suppress Phytophthora blight of
pepper through direct anti-oomycete activities against
mycelial growth, zoospore germination and germ tube
elongation. Bacterial colonization of pepper roots may
be mediated by cell motility and biofilm formation together with chemotaxis to root exudates.
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