Phenazine-1-Carboxylic Acid Production by Pseudomonas fluorescens LBUM636 Alters Phytophthora infestans Growth and Late Blight Development

Abstract

Phytophthora infestans causes late blight of potato, one of the most devastating diseases affecting potato production. Alternative approaches for controlling late blight are being increasingly sought due to increasing environmental concerns over the use of chemical pesticides and the increasing resistance of P. infestans to fungicides. Our research group has isolated a new strain of Pseudomonas fluorescens (LBUM636) of biocontrol interest producing the antibiotic phenazine-1-carboxylic acid (PCA). Wild-type LBUM636 was shown to significantly inhibit the growth of Phytophthora infestans in in vitro confrontational assays whereas its isogenic mutant (phzC-; not producing PCA) only slightly altered the pathogen's growth. Wild-type LBUM636 but not the phzC- mutant also completely repressed disease symptom development on tubers. A pot experiment revealed that wild-type LBUM636 can significantly reduce P. infestans populations in the rhizosphere and in the roots of potato plants, as well as reduce in planta disease symptoms due to PCA production. The expression of eight common plant defense-related genes (ChtA, PR-1b, PR-2, PR-5, LOX, PIN2, PAL-2, and ERF3) was quantified in tubers, roots, and leaves by reverse-transcription quantitative polymerase chain reaction and revealed that the biocontrol observed was not associated with the induction of a plant defense response by LBUM636. Instead, a direct interaction between P. infestans and LBUM636 is required and PCA production appears to be a key factor for LBUM636's biocontrol ability.

Effects of sophorolipids on fungal and oomycete pathogens in relation to pH solubility

“…The objective of this study was to determine the effects of sophorolipids on several fungal and oomycete pathogens and the relationship between sophorolipids at different pH and antimicrobial activities. In addition, Phytophthora infestans causes late blight of potato, one of the most devastating diseases affecting potato production worldwide (Morrison et al ). So, in this paper we further studied the effects of sophorolipids on P. infestans including morphological changes of hyphae, biocontrol of late blight on potato under greenhouse conditions and β‐1,3‐glucanase that is one of the proteases playing a major role in the execution of hyphal tip growth (Taheri‐Talesh et al ).…”

Inoculation With the Plant-Growth-Promoting Rhizobacterium Pseudomonas fluorescens LBUM677 Impacts the Rhizosphere Microbiome of Three Oilseed Crops

“…In order to promote beneficial microbial interactions in the rhizosphere, there is an increasing interest in inoculating plants with beneficial microorganisms ( Aeron et al, 2011 ). Among these organisms, plant growth promoting rhizobacteria (PGPR) represent a functional group including diverse bacterial taxa capable of promoting plant nutrient availability, growth, and disease suppression ( Kloepper et al, 1980 ; Chabot et al, 1993 ; Edwards et al, 2015 ; Morrison et al, 2017 ). Among PGPRs, Pseudomonas spp.…”

Transcriptome alteration in Phytophthora infestans in response to phenazine-1-carboxylic acid production by Pseudomonas fluorescens strain LBUM223

“…PCA is known as an important broad-spectrum antimicrobial compound involved in the biocontrol of various plant pathogens, including Phytophthora spp. [ 22 , 24 , 32 ]. Generally, due to its nitrogen-containing heterocyclic composition, PCA is mainly described as promoting redox reactions and generating reactive oxygen species (ROS), of which the accumulation leads to a reduction in energy production, carbohydrate metabolism, and nutrient uptake [ 33 , 34 ].…”

“…and Pythium spp. [ 22 – 24 ]. PCA displays redox activity and is a nitrated heterocyclic antibiotic compound, notably due to its interference with the electron transport chain [ 25 ].…”