Classification of airborne plant pathogens based on sporulation and infection characteristics

The infection cycles of 26 airborne fungal plant pathogens were compared using six monocyclic variables: latent period, infectious period, sporulation capacity, relative date of sporulation peak, lesion size, and infection efficiency. All variables were measured at the seedling stage in conditions highly conducive to disease development. Multivariate analyses of literature and experimental data were used to describe epidemic strategies based on compensation, addition, and multiplication effects between the monocyclic variables. A typology of fungi according to these effects is proposed, the main divisions of which follow the pattern of lesion growth (semisystemic, local, or negligible). Further subdivisions were obtained based on the other sporulation and infection variables. With a few exceptions, pathogens belonging to the same taxonomic (powdery mildews, downy mildews, rusts) and ecological (biotrophs, necrotrophs) group were grouped together in the proposed typology. Among rusts and necrotrophs, the fungi adapted to temperate and warm climates were also distinguished. The wheat stripe rust was not grouped with the other rusts because of unique epidemiological characteristics, especially semisystemic growth of lesions. Key words: biotrophic fungus, comparative epidemiology, monocyclic process, necrotrophic fungus.

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Growth, infection and aggressiveness of Phytophthora pathogens on Rhododendron leaves

CABI Agriculture and Bioscience ◽

10.1186/s43170-021-00048-5 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Clare R. Taylor ◽

Niklaus J. Grünwald

Keyword(s):

Field Studies ◽

Lesion Size ◽

The Other ◽

Regulatory Agencies ◽

Emerging Pathogens ◽

Whole Plant ◽

Foliar Pathogen ◽

Comparative Epidemiology ◽

Low Levels ◽

Temperature Responses

Abstract Background Phytophthora species are well known as important or emerging pathogens. The genus Rhododendron is of considerable importance to plant regulatory agencies because it is host to many Phytophthora species, most notably, P. ramorum and P. kernoviae. Few studies have directly contrasted the epidemiology of different Phytophthora spp. on a given host. Methods We investigated aspects of the foliar epidemiology (lesion size, sporulation and temperature responses) of P. cactorum, P. cambivora, P. cinnamomi, P. citrophthora, P. foliorum, P. kernoviae, P. lateralis, P. nemorosa, P. nicotianae, P. plurivora, P. ramorum and P. syringae on Rhododendron in detached leaf, whole plant chamber, and field studies. Results P. syringae stood out as it appeared to be a relatively weak pathogen, showing no sporulation and low levels of disease severity, except at low temperatures. P. nicotianae was consistently able to grow at higher temperatures than any of the other Phytophthora spp. and showed higher aggressiveness than any of the other species at high temperatures. P. cinnamomi and P. cactorum, typically thought of as root-infecting species, were able to cause as much foliar disease as P. syringae, a foliar pathogen. P. kernoviae was consistently among the most aggressive species with the highest sporulation. Conclusion These results provide novel insights into the comparative epidemiology of these important established and emerging Phytophthora species.

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Two independent approaches converge to the cloning of a new Leptosphaeria maculans avirulence effector gene, AvrLmS-Lep2

10.1101/2020.10.02.322479 ◽

2020 ◽

Author(s):

Ting Xiang Neik ◽

Kaveh Ghanbarnia ◽

Bénédicte Ollivier ◽

Armin Scheben ◽

Anita Severn-Ellis ◽

...

Keyword(s):

Plant Pathogens ◽

Leptosphaeria Maculans ◽

Lesion Size ◽

Avirulence Gene ◽

Avirulence Genes ◽

Blackleg Disease ◽

Fungal Plant Pathogens ◽

Potential Efficiency ◽

Secretory Signal Peptide

SummaryLeptosphaeria maculans, the causal agent of blackleg disease, interacts with Brassica napus (oilseed rape, canola) in a gene-for-gene manner. The avirulence genes AvrLmS and AvrLep2 were described to be perceived by the resistance genes RlmS and LepR2, respectively, present in the cultivar Surpass 400. Here we report cloning of AvrLmS and AvrLep2 using two independent methods. AvrLmS was cloned using combined in vitro crossing between avirulent and virulent isolates with sequencing of DNA bulks from avirulent or virulent progeny (Bulked-Segregant-Sequencing) to rapidly identify one candidate avirulence gene present in the effector repertoire of L. maculans. AvrLep2 was cloned using a bi-parental cross of avirulent and virulent L. maculans isolates and a classical map-based cloning approach. Taking these two approaches independently, we found that AvrLmS and AvrLep2 are the same gene. Complementation of virulent isolates with this gene confirmed its role in inducing resistance on Surpass 400 and Topas-LepR2. The gene renamed AvrLmS-Lep2 encodes for a small cysteine-rich protein of unknown function with an N-terminal secretory signal peptide, which are common features of the majority of effectors from extracellular fungal plant pathogens. The AvrLmS-Lep2 / LepR2 interaction phenotype was found to vary from a typical hypersensitive response to intermediate resistance sometimes at the edge of, or evolving toward, susceptibility depending on the inoculation conditions. AvrLmS-Lep2 was nevertheless sufficient to significantly reduce the stem lesion size on plant genotypes with LepR2, indicating the potential efficiency of this resistance to control the disease in the field.

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Effect of C6-Volatiles on Bioluminescent Plant Pathogens

HortScience ◽

10.21273/hortsci.33.3.557d ◽

1998 ◽

Vol 33 (3) ◽

pp. 557d-557

Author(s):

Jennifer Warr ◽

Fenny Dane ◽

Bob Ebel

Keyword(s):

Biological Activity ◽

Bacterial Growth ◽

Xanthomonas Campestris ◽

Plant Pathogens ◽

Genetically Engineered ◽

The Other ◽

Computer Assisted ◽

Signal Molecules ◽

Low Concentrations

C6 volatile compounds are known to be produced by the plant upon pathogen attack or other stress-related events. The biological activity of many of these substances is poorly understood, but some might produce signal molecules important in host–pathogen interactions. In this research we explored the possibility that lipid-derived C6 volatiles have a direct effect on bacterial plant pathogens. To this purpose we used a unique tool, a bacterium genetically engineered to bioluminesce. Light-producing genes from a fish-associated bacterium were introduced into Xanthomonas campestris pv. campestris, enabling nondestructive detection of bacteria in vitro and in the plant with special computer-assisted camera equipment. The effects of different C6 volatiles (trans-2 hexanal, trans-2 hexen-1-ol and cis-3 hexenol) on growth of bioluminescent Xanthomonas campestris were investigated. Different volatile concentrations were used. Treatment with trans-2 hexanal appeared bactericidal at low concentrations (1% and 10%), while treatments with the other volatiles were not inhibitive to bacterial growth. The implications of these results with respect to practical use of trans-2 hexanal in pathogen susceptible and resistant plants will be discussed.

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Morphological, biochemical and molecular identification of rhizobacteria isolates with potential for biocontrol of fungal plant pathogens

Archives of Phytopathology and Plant Protection ◽

10.1080/03235408.2021.1909370 ◽

2021 ◽

pp. 1-14

Author(s):

Stephen Larbi-Koranteng ◽

Richard Tuyee Awuah ◽

Fredrick Kankam ◽

Muntala Abdulai ◽

Marian Dorcas Quain ◽

...

Keyword(s):

Molecular Identification ◽

Plant Pathogens ◽

Fungal Plant Pathogens

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Reduction of Selenicereus stem cuttings weight by fungal plant pathogens during storage

Journal of Phytopathology ◽

10.1111/jph.13024 ◽

2021 ◽

Author(s):

John Darby Taguiam ◽

Edzel Evallo ◽

Mark Angelo Balendres

Keyword(s):

Plant Pathogens ◽

Stem Cuttings ◽

Fungal Plant Pathogens

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The carbon source-dependent pattern of antimicrobial activity and gene expression in Pseudomonas donghuensis P482

Scientific Reports ◽

10.1038/s41598-021-90488-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marta Matuszewska ◽

Tomasz Maciąg ◽

Magdalena Rajewska ◽

Aldona Wierzbicka ◽

Sylwia Jafra

Keyword(s):

Gene Expression ◽

Antimicrobial Activity ◽

Carbon Source ◽

Reference Genes ◽

Plant Pathogens ◽

Plant Protection ◽

Carbon Sources ◽

Unknown Compound ◽

Fungal Plant Pathogens ◽

The Impact

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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