Abstract
Scab, caused by Venturia nashicola, is among the most serious diseases of Asian pears and control of this disease largely relies on sterol demethylation inhibitor (DMI) fungicides. However, pear growers have complained about field performance of DMIs since the mid-2000s. In this study, to evaluate pathogen sensitivity, mycelial growth tests and inoculation tests were conducted using DMI-amended culture medium and fungicide-sprayed potted pear trees, respectively. Results confirmed distribution of isolates resistant to fenarimol, hexaconazole, and difenoconazole in the field populations. Importantly, results from tests in culture did not fully correlate with those from tests in planta. Due to phenotypic instability of resistance and poor sporulation of this pathogen in culture, resistance is generally assessed by laborious and time-consuming inoculation with conidia collected from a field. To improve the result interpretation from in vitro tests, the isolates were genotyped: the CYP51 gene which encodes the target sterol 14α-demethylase was sequenced and various mutations have been detected in the coding sequence of DMI-resistant isolates. In addition to the detected single nucleotide polymorphisms, alternative mechanisms, not based on changes in the structure of the target protein, may also increase DMI resistance. Development of molecular methods for the diagnosis of DMI resistance seems to be challenging in V. nashicola.
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Claims 5
Claim · model-written summary
Field populations contained isolates resistant to three DMI fungicides.
- Taxon
- Asian pears
_Pyrus_pyrifolia_flowers.jpg?width=60)
Pyrus pyrifoliae1 - Interactor
- Venturia nashicolaVenturia nashicolae1pathogen
- Outcome
- isolates resistant to fenarimol, hexaconazole, and difenoconazolee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Pyrus_pyrifolia_flowers.jpg?width=500)
Verbatim
e0“Results confirmed distribution of isolates resistant to fenarimol, hexaconazole, and difenoconazole in the field populations.”
e1“Scab, caused by Venturia nashicola, is among the most serious diseases of Asian pears”
Claim · model-written summary
Culture test results did not fully correlate with tests on pear plants.
- Taxon
- pear
_Poirier_Fleurs_et_feuilles.jpg?width=60)
Pyrus communise1 - Outcome
- results from tests in culture did not fully correlate with those from tests in plantae0
- Comparator
- tests in plantae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Poirier_Fleurs_et_feuilles.jpg?width=500)
Verbatim
e0“results from tests in culture did not fully correlate with those from tests in planta.”
e1“fungicide-sprayed potted pear trees”
Claim · model-written summary
Various CYP51 coding mutations were found in DMI-resistant isolates.
- Taxon
- Asian pearsPyrus pyrifoliae1
- Interactor
- Venturia nashicolaVenturia nashicolae1pathogen
- Gene
- CYP51e0
- Outcome
- various mutations have been detected in the coding sequence of DMI-resistant isolatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the CYP51 gene which encodes the target sterol 14α-demethylase was sequenced and various mutations have been detected in the coding sequence of DMI-resistant isolates.”
e1“Scab, caused by Venturia nashicola, is among the most serious diseases of Asian pears”
Claim · model-written summary
The authors suggest mechanisms besides target-protein changes may increase DMI resistance.
- Taxon
- Asian pearsPyrus pyrifoliae1
- Interactor
- Venturia nashicolaVenturia nashicolae1pathogen
- Outcome
- DMI resistancee0
- Qualifier
- alternative mechanisms, not based on changes in the structure of the target proteine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alternative mechanisms, not based on changes in the structure of the target protein, may also increase DMI resistance.”
e1“Scab, caused by Venturia nashicola, is among the most serious diseases of Asian pears”
Claim · model-written summary
Molecular diagnosis of DMI resistance appears challenging in the pathogen.
- Taxon
- Asian pearsPyrus pyrifoliae1
- Interactor
- V. nashicolaVenturia nashicolae0pathogen
- Outcome
- diagnosis of DMI resistancee0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Schema note from the model: Method challenge lacks comparator or value
Verbatim
e0“Development of molecular methods for the diagnosis of DMI resistance seems to be challenging in V. nashicola.”
e1“Asian pears”