In:
PLOS Genetics, Public Library of Science (PLoS), Vol. 19, No. 8 ( 2023-8-31), p. e1010909-
Abstract:
Trichoderma spp. are ubiquitous rhizosphere fungi capable of producing several classes of secondary metabolites that can modify the dynamics of the plant-associated microbiome. However, the bacterial-fungal mechanisms that mediate these interactions have not been fully characterized. Here, a random barcode transposon-site sequencing (RB-TnSeq) approach was employed to identify bacterial genes important for fitness in the presence of Trichoderma atroviride exudates. We selected three rhizosphere bacteria with RB-TnSeq mutant libraries that can promote plant growth: the nitrogen fixers Klebsiella michiganensis M5aI and Herbaspirillum seropedicae SmR1, and Pseudomonas simiae WCS417. As a non-rhizosphere species, Pseudomonas putida KT2440 was also included. From the RB-TnSeq data, nitrogen-fixing bacteria competed mainly for iron and required the siderophore transport system TonB/ExbB for optimal fitness in the presence of T . atroviride exudates. In contrast, P . simiae and P . putida were highly dependent on mechanisms associated with membrane lipid modification that are required for resistance to cationic antimicrobial peptides (CAMPs). A mutant in the Hog1-MAP kinase (Δ tmk 3) gene of T . atroviride showed altered expression patterns of many nonribosomal peptide synthetase (NRPS) biosynthetic gene clusters with potential antibiotic activity. In contrast to exudates from wild-type T . atroviride , bacterial mutants containing lesions in genes associated with resistance to antibiotics did not show fitness defects when RB-TnSeq libraries were exposed to exudates from the Δ tmk3 mutant. Unexpectedly, exudates from wild-type T . atroviride and the Δ tmk 3 mutant rescued purine auxotrophic mutants of H . seropedicae , K . michiganensis and P . simiae . Metabolomic analysis on exudates from wild-type T . atroviride and the Δ tmk 3 mutant showed that both strains excrete purines and complex metabolites; functional Tmk3 is required to produce some of these metabolites. This study highlights the complex interplay between Trichoderma -metabolites and soil bacteria, revealing both beneficial and antagonistic effects, and underscoring the intricate and multifaceted nature of this relationship.
Type of Medium:
Online Resource
ISSN:
1553-7404
DOI:
10.1371/journal.pgen.1010909
DOI:
10.1371/journal.pgen.1010909.g001
DOI:
10.1371/journal.pgen.1010909.g002
DOI:
10.1371/journal.pgen.1010909.g003
DOI:
10.1371/journal.pgen.1010909.g004
DOI:
10.1371/journal.pgen.1010909.g005
DOI:
10.1371/journal.pgen.1010909.g006
DOI:
10.1371/journal.pgen.1010909.g007
DOI:
10.1371/journal.pgen.1010909.g008
DOI:
10.1371/journal.pgen.1010909.s001
DOI:
10.1371/journal.pgen.1010909.s002
DOI:
10.1371/journal.pgen.1010909.s003
DOI:
10.1371/journal.pgen.1010909.s004
DOI:
10.1371/journal.pgen.1010909.s005
DOI:
10.1371/journal.pgen.1010909.s006
Language:
English
Publisher:
Public Library of Science (PLoS)
Publication Date:
2023
detail.hit.zdb_id:
2186725-2
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