DMI-Fungicide Resistance in <i>Venturia nashicola</i>, the Causal Agent of Asian Pear Scab—How Reliable Are Mycelial Growth Tests in Culture?
Scab, caused by <i>Venturia nashicola</i>, 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 s...
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MDPI AG
2021-06-01
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| Series: | Microorganisms |
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| Online Access: | https://www.mdpi.com/2076-2607/9/7/1377 |
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| author | Hideo Ishii Hans Jorgen Cools Kumiko Nishimura Lorenzo Borghi Kenji Kikuhara Yuichi Yamaoka |
| author_facet | Hideo Ishii Hans Jorgen Cools Kumiko Nishimura Lorenzo Borghi Kenji Kikuhara Yuichi Yamaoka |
| author_sort | Hideo Ishii |
| collection | DOAJ |
| description | Scab, caused by <i>Venturia nashicola</i>, 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 <i>CYP51</i> 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 <i>V</i>. <i>nashicola</i>. |
| first_indexed | 2024-03-10T10:05:20Z |
| format | Article |
| id | doaj.art-2db706340504484e936efc3e6c5bb0fc |
| institution | Directory Open Access Journal |
| issn | 2076-2607 |
| language | English |
| last_indexed | 2024-03-10T10:05:20Z |
| publishDate | 2021-06-01 |
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| record_format | Article |
| series | Microorganisms |
| spelling | doaj.art-2db706340504484e936efc3e6c5bb0fc2023-11-22T01:36:02ZengMDPI AGMicroorganisms2076-26072021-06-0197137710.3390/microorganisms9071377DMI-Fungicide Resistance in <i>Venturia nashicola</i>, the Causal Agent of Asian Pear Scab—How Reliable Are Mycelial Growth Tests in Culture?Hideo Ishii0Hans Jorgen Cools1Kumiko Nishimura2Lorenzo Borghi3Kenji Kikuhara4Yuichi Yamaoka5Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba 305-8572, JapanSyngenta, Jealott’s Hill International Research Centre, Bracknell RG42 6EY, UKNational Institute for Agro-Environmental Sciences, Kannondai 3-1-3, Tsukuba 305-8604, JapanSyngenta Crop Protection AG, Werk Stein, Schaffhauserstrasse, WST.820.2.79, CH-4332 Stein, SwitzerlandFukuoka Agriculture and Forestry Research Center, Yoshiki 587, Chikushino 818-8549, JapanFaculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba 305-8572, JapanScab, caused by <i>Venturia nashicola</i>, 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 <i>CYP51</i> 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 <i>V</i>. <i>nashicola</i>.https://www.mdpi.com/2076-2607/9/7/1377CYP51DMIsfungicide resistancepear scabsensitivity tests<i>Venturia nashicola</i> |
| spellingShingle | Hideo Ishii Hans Jorgen Cools Kumiko Nishimura Lorenzo Borghi Kenji Kikuhara Yuichi Yamaoka DMI-Fungicide Resistance in <i>Venturia nashicola</i>, the Causal Agent of Asian Pear Scab—How Reliable Are Mycelial Growth Tests in Culture? Microorganisms CYP51 DMIs fungicide resistance pear scab sensitivity tests <i>Venturia nashicola</i> |
| title | DMI-Fungicide Resistance in <i>Venturia nashicola</i>, the Causal Agent of Asian Pear Scab—How Reliable Are Mycelial Growth Tests in Culture? |
| title_full | DMI-Fungicide Resistance in <i>Venturia nashicola</i>, the Causal Agent of Asian Pear Scab—How Reliable Are Mycelial Growth Tests in Culture? |
| title_fullStr | DMI-Fungicide Resistance in <i>Venturia nashicola</i>, the Causal Agent of Asian Pear Scab—How Reliable Are Mycelial Growth Tests in Culture? |
| title_full_unstemmed | DMI-Fungicide Resistance in <i>Venturia nashicola</i>, the Causal Agent of Asian Pear Scab—How Reliable Are Mycelial Growth Tests in Culture? |
| title_short | DMI-Fungicide Resistance in <i>Venturia nashicola</i>, the Causal Agent of Asian Pear Scab—How Reliable Are Mycelial Growth Tests in Culture? |
| title_sort | dmi fungicide resistance in i venturia nashicola i the causal agent of asian pear scab how reliable are mycelial growth tests in culture |
| topic | CYP51 DMIs fungicide resistance pear scab sensitivity tests <i>Venturia nashicola</i> |
| url | https://www.mdpi.com/2076-2607/9/7/1377 |
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