Location of an Intron in the Cytochrome b Gene Indicates Reduced Risk of QoI Fungicide Resistance in Fusicladium effusum

Pecan scab, caused by Fusicladium effusum, is most effectively managed using multiple fungicide applications, including quinone outside inhibitors (QoIs). However, QoIs have a high risk for resistance developing in phytopathogenic fungi. QoI resistance is generally associated with amino-acid substitutions at positions 129, 137, and 143 of the cytochrome b (cytb) gene. A substitution at position 143 confers complete resistance, while an intron immediately downstream of this position prevents the substitution. The objective of this study was to assess the risk of QoI resistance by characterizing a partial fragment of the F. effusum cytb gene. Sequence analysis of the 1,919-bp fragment revealed the presence of a 1,407-bp intron immediately downstream of position 143. This intron was identified in 125 isolates collected from 16 counties across the state of Georgia. No substitutions were identified at positions 129 or 143 but, in seven of the isolates, glycine was replaced with serine at position 137. The ubiquitous nature of the detected intron provided strong evidence that the G143A substitution may not occur in F. effusum isolates, although resistance could still develop through intron loss events or the selection of intron-lacking genotypes, or as the result of other mutations in the cytb gene.

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Antibacterial, cytotoxic and trypanocidal activities of marine-derived fungi isolated from Philippine macroalgae and seagrasses

Acta Botanica Croatica ◽

10.2478/botcro-2018-0016 ◽

2018 ◽

Vol 77 (2) ◽

pp. 141-151 ◽

Cited By ~ 5

Author(s):

Kin Israel Notarte ◽

Takashi Yaguchi ◽

Keisuke Suganuma ◽

Thomas Edison dela Cruz

Keyword(s):

Gene Sequence ◽

Culture Media ◽

Artemia Salina ◽

Malt Extract ◽

Zone Of Inhibition ◽

Potato Dextrose Broth ◽

Gene Sequence Analysis ◽

Marine Salt ◽

Mycelia Sterilia ◽

Selection Of

AbstractThe occurrence and bioactivities of marine-derived fungi are evaluated in this paper. A total of 16 morphospecies of marine-derived fungi (MDF) were isolated from four host macroalgae and two seagrasses and identified as belonging to the generaAspergillus,Fusarium,Paecilomyces,Penicillium,Sclerotinia,ThamnidiumandTrichoderma, including fivemycelia sterilia.Among these host organisms, the rhodophyteLaurencia intermediaharboured the highest number of isolated MDF. Selected MDF were then assayed and showed to inhibitPseudomonas aeruginosa(8-19 mm zone of inhibition) andStaphylococcus aureus(6-19 mm zone of inhibition), and were cytotoxic against the brine shrimpArtemia salinanauplii (LD50: 201.56-948.37 μg mL−1). The screening led to the selection of five of the most bioactive morphospecies, all belonging to the genusAspergillus. These marine aspergilli were subjected toβ-tubulingene sequence analysis for species identification, and to mass production in different culture media with or without marine salts, and screening of the crude culture extracts for their cytotoxic and trypanocidal activities.Aspergillus tubingensiscultivated in potato dextrose broth with marine salt proved to be the most cytotoxic against P388 (IC50: 1028 ng mL−1) and HeLa (IC50: 1301 ng mL−1) cancer cells. On the other hand,A. fumigatuscultivated in malt extract broth without marine salt was shown to be the most potent againstTrypanosoma congolense(IC50: 298.18 ng mL−1). Our study therefore showed that salinity may influence the bioactivities of some species of MDF.

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Geographic Distribution of Leishmania Species in Ecuador Based on the Cytochrome B Gene Sequence Analysis

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0004844 ◽

2016 ◽

Vol 10 (7) ◽

pp. e0004844 ◽

Cited By ~ 12

Author(s):

Hirotomo Kato ◽

Eduardo A. Gomez ◽

Luiggi Martini-Robles ◽

Jenny Muzzio ◽

Lenin Velez ◽

...

Keyword(s):

Sequence Analysis ◽

Cytochrome B ◽

Geographic Distribution ◽

Gene Sequence ◽

Leishmania Species ◽

Cytochrome B Gene ◽

Gene Sequence Analysis

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Detection and Characterization of QoI-Resistant Phytophthora cactorum and P. nicotianae Causing Leather Rot in Florida Strawberry

Plant Disease ◽

10.1094/pdis-08-21-1658-re ◽

2021 ◽

Author(s):

Marcus Vinicius Marin ◽

Teresa E Seijo ◽

Ellias Zuchelli ◽

Natalia A. Peres

Keyword(s):

Point Mutations ◽

Crown Rot ◽

Cytb Gene ◽

Phytophthora Cactorum ◽

Phytophthora Spp ◽

Mitochondrial Cytochrome B ◽

Qualitative Resistance ◽

Selection Of ◽

Qoi Resistance

Phytophthora cactorum and P. nicotianae cause leather rot (LR) of fruit and Phytophthora crown rot (PhCR) in strawberry. LR occurs sporadically but can cause up to 70% fruit loss when weather is conducive. In Florida's annual strawberry winter production system, PhCR can be severe, resulting in plant stunting, mortality, and severe yield loss. Currently, azoxystrobin is labeled for control of LR but not for PhCR. The aims of this research were i) to determine the sensitivity of P. cactorum and P. nicotianae isolates from strawberry to azoxystrobin and ii) to investigate mechanisms of QoI-resistance present in P. cactorum and P. nicotianae based on the known point mutations within the cytb gene. Isolates of both Phytophthora spp. causing LR and PhCR were collected from multiple strawberry fields in Florida between 1997 and 2020. Isolates were tested for sensitivity to azoxystrobin at 0, 0.01, 0.1, 1.0, 10, and 50 µg/ml on potato dextrose agar (PDA) amended with SHAM (100 µg/ml). Isolates were separated into two groups, sensitive isolates, with the 50% effective concentration (EC50) values lower than 1.0 µg/ml, and resistant isolates having EC50 values higher than 50 µg/ml. P. cactorum and P. nicotianae resistance to azoxystrobin was found for isolates collected after 2010. The first 450 nucleotides of the mitochondrial cytochrome b (cytb) gene were sequenced from a selection of resistant and sensitive isolates of both species. The G143A mutation reported to confer resistance to azoxystrobin was found in all resistant P. cactorum isolates. However, in P. nicotianae, qualitative resistance was observed, but the isolates lacked all the known mutations in the cytb gene. This is the first report of resistance to azoxystrobin in P. cactorum and P. nicotianae.

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