Using structural variants to understand the ecological and evolutionary dynamics of fungal plant pathogens

AbstractPseudomonas donghuensis P482 is a tomato rhizosphere isolate with the ability to inhibit growth of bacterial and fungal plant pathogens. Herein, we analysed the impact of the carbon source on the antibacterial activity of P482 and expression of the selected genes of three genomic regions in the P482 genome. These regions are involved in the synthesis of pyoverdine, 7-hydroxytropolone (7-HT) and an unknown compound (“cluster 17”) and are responsible for the antimicrobial activity of P482. We showed that the P482 mutants, defective in these regions, show variations and contrasting patterns of growth inhibition of the target pathogen under given nutritional conditions (with glucose or glycerol as a carbon source). We also selected and validated the reference genes for gene expression studies in P. donghuensis P482. Amongst ten candidate genes, we found gyrB, rpoD and mrdA the most stably expressed. Using selected reference genes in RT-qPCR, we assessed the expression of the genes of interest under minimal medium conditions with glucose or glycerol as carbon sources. Glycerol was shown to negatively affect the expression of genes necessary for 7-HT synthesis. The significance of this finding in the light of the role of nutrient (carbon) availability in biological plant protection is discussed.

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Stress-Activated Protein Kinase Signalling Regulates Mycoparasitic Hyphal-Hyphal Interactions in Trichoderma atroviride

Journal of Fungi ◽

10.3390/jof7050365 ◽

2021 ◽

Vol 7 (5) ◽

pp. 365

Author(s):

Dubraska Moreno-Ruiz ◽

Linda Salzmann ◽

Mark D. Fricker ◽

Susanne Zeilinger ◽

Alexander Lichius

Keyword(s):

Protein Kinase ◽

Map Kinases ◽

Plant Pathogens ◽

Tip Growth ◽

Mitogen Activated Protein Kinase ◽

Trichoderma Atroviride ◽

Contact Phase ◽

Fungal Plant Pathogens ◽

Signalling Network ◽

Mapk Signalling

Trichoderma atroviride is a mycoparasitic fungus used as biological control agent against fungal plant pathogens. The recognition and appropriate morphogenetic responses to prey-derived signals are essential for successful mycoparasitism. We established microcolony confrontation assays using T. atroviride strains expressing cell division cycle 42 (Cdc42) and Ras-related C3 botulinum toxin substrate 1 (Rac1) interactive binding (CRIB) reporters to analyse morphogenetic changes and the dynamic displacement of localized GTPase activity during polarized tip growth. Microscopic analyses showed that Trichoderma experiences significant polarity stress when approaching its fungal preys. The perception of prey-derived signals is integrated via the guanosine triphosphatase (GTPase) and mitogen-activated protein kinase (MAPK) signalling network, and deletion of the MAP kinases Trichoderma MAPK 1 (Tmk1) and Tmk3 affected T. atroviride tip polarization, chemotropic growth, and contact-induced morphogenesis so severely that the establishment of mycoparasitism was highly inefficient to impossible. The responses varied depending on the prey species and the interaction stage, reflecting the high selectivity of the signalling process. Our data suggest that Tmk3 affects the polarity-stress adaptation process especially during the pre-contact phase, whereas Tmk1 regulates contact-induced morphogenesis at the early-contact phase. Neither Tmk1 nor Tmk3 loss-of-function could be fully compensated within the GTPase/MAPK signalling network underscoring the crucial importance of a sensitive polarized tip growth apparatus for successful mycoparasitism.

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Metabolites of rhizobacteria antagonistic towards fungal plant pathogens

Annals of Microbiology ◽

10.1007/bf03175061 ◽

2007 ◽

Vol 57 (1) ◽

pp. 127-130 ◽

Cited By ~ 2

Author(s):

Garima Jha ◽

Vanamala Anjaiah

Keyword(s):

Plant Pathogens ◽

Fungal Plant Pathogens

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Effectors of biotrophic fungal plant pathogens

Functional Plant Biology ◽

10.1071/fp10072 ◽

2010 ◽

Vol 37 (10) ◽

pp. 913 ◽

Cited By ~ 12

Author(s):

Pamela H. P. Gan ◽

Maryam Rafiqi ◽

Adrienne R. Hardham ◽

Peter N. Dodds

Keyword(s):

Plant Tissue ◽

Fungal Pathogen ◽

Plant Pathogens ◽

Plant Cells ◽

Host Cells ◽

Plant Proteins ◽

Living Plant ◽

Host Cytoplasm ◽

Fungal Plant Pathogens ◽

Biotrophic Fungi

Plant pathogenic biotrophic fungi are able to grow within living plant tissue due to the action of secreted pathogen proteins known as effectors that alter the response of plant cells to pathogens. The discovery and identification of these proteins has greatly expanded with the sequencing and annotation of fungal pathogen genomes. Studies to characterise effector function have revealed that a subset of these secreted pathogen proteins interact with plant proteins within the host cytoplasm. This review focuses on the effectors of intracellular biotrophic and hemibiotrophic fungal plant pathogens and summarises advances in understanding the roles of these proteins in disease and in elucidating the mechanism of fungal effector uptake into host cells.

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