Development of New Fungicide, Metominostrobin

Masuko, Michio; Kataoka, Takahiro; Ichinari, Mitsuhiro; Niikawa, Motomu

doi:10.1584/jpestics.26.203

Cited by 6 publications

(8 citation statements)

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“…Metominostrobin belongs to the methoxyacrylate fungicides and inhibits respiration by blocking electron flux at Qo site in complex III. 21) The target pathogen, M. oryzae, induces cyanide-resistant AOX respiration when the cytochrome-mediated pathway was blocked by the chemical. Superoxide anion is considered to be involved in the metominostrobin-dependent induction of cyanide-resistant respiration.…”

Section: Fungicides Acting On Respiratory Chain Of Fungal Mitochondriamentioning

confidence: 99%

Recent Topics on Action Mechanisms of Fungicides

Yamaguchi

Fujimura

2005

J. Pestic. Sci.

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When the rice blast pathogen Magnaporthe oryzae recognizes J. Pestic. Sci., 30(2), 67-74 (2005) * To whom correspondence should be addressed. E-mail: yamaism@riken.jp © Pesticide Science Society of Japan Recent Topics on Action Mechanisms of FungicidesIsamu YAMAGUCHI* and Makoto FUJIMURA † Plant Science Center, Tsurumi, Yokohama,, Japan † Faculty of Life Science, University of Toyo, Itakura, Oura-gun, Gunma 374-0193, Japan (Received December 27, 2004) Plant diseases are damaging to crop production in a temperate and humid climate like that of Japan, which has resulted in the development of many excellent fungicides, but wide-spread use of site-specific fungicides can cause pathogens to develop resistance in the field. While all modern fungicides have been developed through extensive safety evaluation, there is deep public concern about their side effects on non-target organisms. Thus there is a growing interest in non-fungicidal disease-controlling agents since they are supposedly specific to target organisms and less likely to cause resistance. Review the surface characteristics of the host plants such as lipophilicity and hardness, its germinating hypha starts differentiating a special cell termed an appressorium to infect the plant. The formation of appressoria involves signal transduction and the expression of many genes. Then, appressorial cells mature by forming a layer of melanin on the innermost part of the cell wall, which affords high osmotic pressure generated inside the cell to penetrate the cuticle layer of the host plant. Thus if melanin biosynthesis is inhibited, the pathogen cannot exert its pathogenicity. In fact, melanin biosynthesis inhibitors (MBIs) are primarily not toxic to the vegetative growth of M. oryzae, but achieve outstanding control of the blast disease in vivo. Actually there are two types of melanin biosynthesis inhibitors; hydroxynaphthalene reductase inhibitors (MBI-R: fthalide, tricyclazole and pyroquilon) and scytalone dehydratase inhibitors (MBI-D: carpropamid, diclocymet and fenoxanil). The buff mutants of M. oryzae were shown to phenotypically resemble the MBI-R-treated wildtype strains and were essentially nonpathogenic to rice plant, which suggested that a melanin biosynthetic pathway is indispensable for the appressoria to obtain infectiosity. RIKEN 1)Carpropamid was developed as a novel potent controlling agent against the rice blast, 2) and enzyme kinetic data showed that carpropamid is a tight-binding competitive inhibitor of scytalone dehydratase (STD), a key enzyme in the biosynthesis of melanin. Its calculated Ki value was 140 pM, which is more than 10 5 times smaller than the Km for scytalone. 3,4) An X-ray analysis of the crystal structure of the STD complex with carpropamid identified interactions that determine the tight-binding 5) as shown in Fig. 1. Three types of interactions were considered important for the binding: (1) a strong hydrogen bond between N131 (Asn 131) and chlorine, (2) two hydrogen bonds mediated by water molecules (WTA) and (3) the i...

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Section: Fungicides Acting On Respiratory Chain Of Fungal Mitochondriamentioning

confidence: 99%

Recent Topics on Action Mechanisms of Fungicides

Yamaguchi

Fujimura

2005

J. Pestic. Sci.

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“…are not highly sensitive to QoI upon agar plate tests, which are commonly used for other fungicide classes such as for sterol biosynthesis inhibitors, even though those fungi are highly QoI‐sensitive in in planta tests 5,6 . The reason for the low sensitivity in agar plate tests is attributed mainly to the expression of alternative oxidase (AOX), which can regulate the redox balance in mitochondria by oxidizing redundant ubiquinol 7–12 . By contrast, this enzyme plays a minor role in in planta QoI sensitivity as it does not generate sufficient ATP to achieve complex and energy‐consuming host infection processes 13 .…”

Section: Introductionmentioning

confidence: 99%

“…13 In addition, some reports have indicated that plant flavonoids inhibit the induction of AOX. 9 Therefore, normal agar plate tests using mycelium inoculum are not always appropriate to confirm QoI sensitivity. In cases where AOX is the main reason for low sensitivity in common agar medium, iron chelating agents such as salicylhydroxamic acid (SHAM) or n-propyl gallate have been used successfully to minimize the influence of AOX, as it is an iron-requiring metalloenzyme.…”

Section: Introductionmentioning

confidence: 99%

“…5,6 The reason for the low sensitivity in agar plate tests is attributed mainly to the expression of alternative oxidase (AOX), which can regulate the redox balance in mitochondria by oxidizing redundant ubiquinol. [7][8][9][10][11][12] By contrast, this enzyme plays a minor role in in planta QoI sensitivity as it does not generate sufficient ATP to achieve complex and energy-consuming host infection processes. 13 In addition, some reports have indicated that plant flavonoids inhibit the induction of AOX.…”

Section: Introductionmentioning

confidence: 99%

“…By contrast, this enzyme plays a minor role in in planta QoI sensitivity as it does not generate sufficient ATP to achieve complex and energy‐consuming host infection processes 13 . In addition, some reports have indicated that plant flavonoids inhibit the induction of AOX 9 . Therefore, normal agar plate tests using mycelium inoculum are not always appropriate to confirm QoI sensitivity.…”

Section: Introductionmentioning

confidence: 99%

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Microtiter plate test using liquid medium is an alternative method for monitoring metyltetraprole sensitivity in Cercospora beticola

Matsuzaki

Uda

Kurahashi

et al. 2020

Pest Management Science

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BACKGROUND Metyltetraprole is a new quinone outside inhibitor (QoI) fungicide showing potent activity against QoI‐resistant fungi that possess the G143A cytochrome b mutation, which confers resistance to existing QoIs such as trifloxystrobin. For its sustainable use, monitoring of metyltetraprole sensitivity is necessary and the establishment of appropriate methodology is important in each pathogen species. RESULTS In Cercospora beticola, the causal agent of sugar beet leaf spot, some isolates were less sensitive to metyltetraprole (EC50 > 1 mg L–1, higher than the saturated concentration) using the common agar plate method, even with 100 mg L−1 salicylhydroxamic acid, an alternative oxidase inhibitor. However, microtiter tests (EC50 < 0.01 mg L−1), conidial germination tests (EC50 < 0.01 mg L−1) and in planta tests (>80% control at 75 mg L−1 run‐off spraying) confirmed that all tested isolates were highly sensitive to metyltetraprole. For trifloxystrobin, G143A mutants were clearly resistant upon microtiter plate tests (median EC50 > 2 mg L−1) and distinct from wild‐type isolates (median EC50 < 0.01 mg L−1). Notably, mycelium fragments were usable for the microtiter plate tests and the test was applicable for isolates that do not form sufficient conidia. Our monitoring study by microtiter plate tests did not indicate the presence of metyltetraprole‐resistant C. beticola isolates in populations in Hokkaido, Japan. CONCLUSION The microtiter tests were revealed to be useful for monitoring the sensitivity of C. beticola to metyltetraprole and trifloxystrobin. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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