Molecular analyses indicate that both native and exotic pathogen populations serve as sources of novel outbreaks of Cypress Canker Disease

SUMMARYInteractions between commensal microbes and invading pathogens are understudied, despite their likely effects on pathogen population structure and infection processes. We describe the population structure and genetic diversity of a broad range of co-occurringPseudomonas syringaeisolated from infected and uninfected kiwifruit during an outbreak of bleeding canker disease caused byP. syringaepv.actinidiae(Psa) in New Zealand. Overall population structure was clonal and affected by ecological factors including infection status and cultivar. Most isolates are members of a new clade in phylogroup 3 (PG3a), also present on kiwifruit leaves in China and Japan. Stability of the polymorphism between pathogenicPsaand commensalP. syringaePG3a isolated from the same leaf was tested using reciprocal invasion from rare assaysin vitroand in planta.P. syringaeG33C (PG3a) inhibitedPsaNZ54, while the presence ofPsaNZ54 enhanced the growth ofP. syringaeG33C. This effect could not be attributed to virulence activity encoded by the Type 3 secretion system ofPsa. Together our data contribute toward the development of an ecological perspective on the genetic structure of pathogen populations.ORIGINALITY-SIGNIFICANT STATEMENTBacterial pathogen populations are often studied with little consideration of co-occurring microbes and yet interactions between pathogens and commensals can affect both population structure and disease progression. A fine-scale sampling of commensals present on kiwifruit leaves during an outbreak of bleeding canker disease caused byP. syringaepv.actinidiaereveals a clonal population structure. A new clade of non-pathogenicP. syringae(PG3a) appears to be associated with kiwifruit on a global scale. The presence of PG3a on kiwifruit has significant effects on the outcome of infection byP. syringaepv.actinidiae. This emphasises the value of studying the effect of co-occurring bacteria on pathogen-plant interactions.

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Limiting Populations and Spread of Clavibacter michiganensis subsp. michiganensis on Seedling Tomatoes in the Greenhouse

Plant Disease ◽

10.1094/pdis.2002.86.5.535 ◽

2002 ◽

Vol 86 (5) ◽

pp. 535-542 ◽

Cited By ~ 29

Author(s):

N. A. Werner ◽

D. W. Fulbright ◽

R. Podolsky ◽

J. Bell ◽

M. K. Hausbeck

Keyword(s):

Bacterial Canker ◽

Susceptible Cultivar ◽

Copper Hydroxide ◽

Clavibacter Michiganensis ◽

Canker Disease ◽

Resistant Cultivars ◽

Tomato Seedlings ◽

Greenhouse Tomato ◽

Clavibacter Michiganensis Subsp ◽

Pathogen Populations

Symptomless greenhouse tomato transplants may harbor high populations of Clavibacter michiganensis subsp. michiganensis, the causal agent of bacterial canker, leading to yield loss in the field. The objective of this study was to determine whether resistant cultivars, acibenzolar-S-methyl, avirulent strains of C. michiganensis subsp. michiganensis, or standard bactericides reduce pathogen populations and spread among greenhouse tomato seedlings. All treatments limited pathogen populations compared with the untreated inoculated susceptible cultivar in 1996 and 1998, but not in 1997. In 1996, copper hydroxide alone or mixed with mancozeb or streptomycin limited pathogen populations relative to acibenzolar-S-methyl, acibenzolar-S-methyl mixed with copper hydroxide, and avirulent strains. Copper hydroxide mixed with streptomycin limited pathogen populations compared with copper hydroxide mixed with mancozeb. Adding copper hydroxide to acibenzolar-S-methyl limited pathogen populations compared with acibenzolar-S-methyl alone. In 1998, treatments did not differ significantly from each other in limiting pathogen populations. The treatments limited spread of the bacterium only in 1997. Copper hydroxide mixed with mancozeb limited spread compared with copper hydroxide mixed with streptomycin. Pathogen spread was also reduced among resistant cultivars compared with the susceptible cultivar treated with streptomycin. In the field, the untreated inoculated susceptible cultivar produced yields that were 61% (1996) and 93% (1997) of those produced by the uninoculated susceptible cultivar. Fruit spotting occurred regardless of treatment. To prevent severe bacterial canker disease in the field, growers should initiate and sustain bactericide applications to tomato transplants while in the greenhouse to suppress pathogen populations. Cultivar resistance and acibenzolar-S-methyl may be helpful in disease management of bacterial canker on tomato.

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A polyphasic approach (metabolomics, morphological and molecular analyses) in the systematics of Cladobotryum species in Greece

Planta Medica ◽

10.1055/s-0032-1320657 ◽

2012 ◽

Vol 78 (11) ◽

Cited By ~ 2

Author(s):

N Milic ◽

S Kostidis ◽

A Stavrou ◽

Z Gonou-Zagou ◽

VN Kouvelis ◽

...

Keyword(s):

Polyphasic Approach ◽

Molecular Analyses

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First record of the soil cyanobacterium Nodosilinea epilithica (Synechococcales, Cyanobacteria) in Russia

Novosti sistematiki nizshikh rastenii ◽

10.31111/nsnr/2016.50.125 ◽

2016 ◽

Vol 50 ◽

pp. 125-141

Author(s):

A. D. Temraleeva ◽

S. A. Dronova

Keyword(s):

Chestnut Soil ◽

First Record ◽

Molecular Analyses ◽

Dry Steppes ◽

Cyanobacterial Culture ◽

Volgograd Region ◽

First Time

Nodosilinea epilithica Perkerson et Casamatta is reported for the first time for Russia. The sample was isolated from a typical chestnut soil in the zone of dry steppes (Volgograd Region) and its identity was confirmed by morphological and molecular analyses. The specific feature of the studied strain is its ability to form nodules at normal (60–75 μmol photons ∙ m-2 ∙ sec-1) light. The number of nodules is supposed to be related to the age of a cyanobacterial culture.

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Rubiacearum Americanarum Magna Hama Pars XLV: More New Species and Taxonomic Changes in Palicourea (Rubiaceae, Palicoureeae) and Psychotria subg. Heteropsychotria

Novon A Journal for Botanical Nomenclature ◽

10.3417/2019387 ◽

2019 ◽

Vol 27 (3) ◽

pp. 165-195

Author(s):

Charlotte M. Taylor

Keyword(s):

New Species ◽

Molecular Analyses ◽

The Andes ◽

Taxonomic Changes ◽

Species Groups ◽

Three New Species ◽

Taxonomic Studies

Psychotria subg. Heteropsychotria Steyerm. has been shown by morphological and molecular analyses to be polyphyletic. Most of its species, including its type, belong to Palicourea Aubl. (“Pal.”). Thirty-two species of this group are reviewed here, and 17 species in Psychotria L. are transferred to Palicourea and one to Rudgea Salisb. Two replacement names, Pal. agudeloana C. M. Taylor and Pal. tabayensis C. M. Taylor, are published. Taxonomic studies here clarify circumscriptions of similar, often-confused species for several distinctive species groups found variously in Mesoamerica and the Andes: the Palicourea aschersonianoides group, the Palicourea galeottiana group, the Palicourea sulphurea group, and the Palicourea tristis group. Three new species of Palicourea are described: Pal. aschersonianula C. M. Taylor, Pal. gonzaleziana C. M. Taylor, and Pal. wachterae C. M. Taylor. Nineteen names are newly typified, and infrageneric classifications are noted for the species of Palicourea studied.

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Potential for outcrossing in an apparently asexual population ofFusarium circinatum, the causal agent of pitch canker disease

Mycologia ◽

10.1080/00275514.2000.12061256 ◽

2000 ◽

Vol 92 (6) ◽

pp. 1085-1090 ◽

Cited By ~ 2

Author(s):

Karen Wikler ◽

Thomas R. Gordon ◽

Sharon L. Clark ◽

Michael J. Wingfield ◽

Henriette Britz

Keyword(s):

Causal Agent ◽

Pitch Canker ◽

Asexual Population ◽

Canker Disease

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Escalation of Pyrethroid Resistance in the Malaria Vector Anopheles funestus Induces a Loss of Efficacy of Piperonyl Butoxide–Based Insecticide-Treated Nets in Mozambique

The Journal of Infectious Diseases ◽

10.1093/infdis/jiz139 ◽

2019 ◽

Vol 220 (3) ◽

pp. 467-475 ◽

Cited By ~ 16

Author(s):

Jacob M Riveron ◽

Silvie Huijben ◽

Williams Tchapga ◽

Magellan Tchouakui ◽

Murielle J Wondji ◽

...

Keyword(s):

Cytochrome P450 ◽

Pyrethroid Resistance ◽

Anopheles Funestus ◽

Resistance Mechanisms ◽

Piperonyl Butoxide ◽

Insecticide Treated Nets ◽

Molecular Analyses ◽

Cytochrome P450 Genes ◽

High Degree ◽

Long Lasting Insecticidal Nets

Abstract Background Insecticide resistance poses a serious threat to insecticide-based interventions in Africa. There is a fear that resistance escalation could jeopardize malaria control efforts. Monitoring of cases of aggravation of resistance intensity and its impact on the efficacy of control tools is crucial to predict consequences of resistance. Methods The resistance levels of an Anopheles funestus population from Palmeira, southern Mozambique, were characterized and their impact on the efficacy of various insecticide-treated nets established. Results A dramatic loss of efficacy of all long-lasting insecticidal nets (LLINs), including piperonyl butoxide (PBO)–based nets (Olyset Plus), was observed. This An. funestus population consistently (2016, 2017, and 2018) exhibited a high degree of pyrethroid resistance. Molecular analyses revealed that this resistance escalation was associated with a massive overexpression of the duplicated cytochrome P450 genes CYP6P9a and CYP6P9b, and also the fixation of the resistance CYP6P9a_R allele in this population in 2016 (100%) in contrast to 2002 (5%). However, the low recovery of susceptibility after PBO synergist assay suggests that other resistance mechanisms could be involved. Conclusions The loss of efficacy of pyrethroid-based LLINs with and without PBO is a concern for the effectiveness of insecticide-based interventions, and action should be taken to prevent the spread of such super-resistance.

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Discovery of the freshwater sponge genus Corvospongilla Annandale (Porifera: Spongillida) in Australia with the description of a new species and phylogeographic implications

Limnology ◽

10.1007/s10201-021-00670-2 ◽

2021 ◽

Author(s):

Renata Manconi ◽

Dirk Erpenbeck ◽

Jane Fromont ◽

Gert Wörheide ◽

Roberto Pronzato

Keyword(s):

New Species ◽

Morphological Traits ◽

Freshwater Sponge ◽

Freshwater Sponges ◽

Molecular Analyses ◽

Biogeographic Patterns ◽

Hydrographic Basin ◽

Integrative Systematics ◽

North Western ◽

A New Species

AbstractA recent discovery of freshwater sponges in an unexplored hydrographic basin in north-western Australia provided the opportunity to investigate the genus Corvospongilla Annandale (Spongillida: Spongillidae) using integrative systematics. Emendation of the genus diagnosis is provided. A comparative analysis of a Corvospongilla global dataset of morphological traits together with biogeographic patterns disclosed a new Australasian Corvospongilla species and along with molecular analyses provided the basis for a phylogenetic and phylogeographic tree for some Asian, Afrotropical and Australasian lineages.

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