Antifungal activity of metyltetraprole against the existing QoI‐resistant isolates of various plant pathogenic fungi

Abstract

BACKGROUND Metyltetraprole is a novel quinol oxidation site of Complex III inhibitor (QoI) fungicide that inhibits mitochondrial electron transport at the Qo site of the cytochrome bc1 complex. Previous reports have demonstrated that it is also active against the QoI‐resistant (QoI‐R) isolates of Zymoseptoria tritici and Pyrenophora teres with the mutations G143A and F129L in their cytochrome b gene, respectively. Further studies on cross‐resistance between metyltetraprole and existing QoIs were performed using an increased number of isolates of Z. tritici, P. teres, Ramularia collo‐cygni, Pyrenophora tritici‐repentis, and several other plant pathogenic fungi. RESULTS Differences in the EC50 values between the wild‐type and QoI‐R isolates with the mutations G143A or F129L were always smaller for metyltetraprole compared to those for the existing QoIs, and they were never greater than five in terms of resistance factor. The 2‐year field experiments showed that the metyltetraprole treatment did not increase the percentage of QoI‐R isolates likely to harbor the G143A mutation in a Z. tritici population. CONCLUSION The unique behavior of metyltetraprole against the existing QoI‐R isolates was confirmed for all tested pathogen species. Our results provide important information to establish a fungicide resistance management strategy using metyltetraprole in combination or alternation with other fungicides. © 2019 Society of Chemical Industry

Fungicide Resistance Evolving in Ramularia collo-cygni Population in Estonia

“…The continuous use of strobilurins in commercial fields creates favorable conditions for the further spread of R. collo-cygni strains carrying G143A. In 2020, a member of a new generation of QoI metyltetraprole was successfully tested against QoI-resistant strains of pathogenic fungi with G143A mutation; all tested isolates were highly susceptible to metyltetraprole [ 53 ]. This new active ingredient is expected to replace some of the currently available QoIs due to its high intrinsic activity on R. collo-cygni , as shown in several laboratory and greenhouse tests [ 53 ].…”

Study of Metyltetraprole, an unusual agrofungicide targeting the Qo-site of cytochrome bc1 complex

“…It could be expected that a same mutation could have a different impact depending of the species. For example, growth sensitivity assays performed with various plant pathogen fungi bearing F129L revealed RFs for MTP between 0.7 and 3.3, and RFs for azoxystrobin between 18.5 and 204.3 [3]. We have previously observed that modification of the Qo-site by replacing a few residues of the yeast enzyme by their equivalents in humans or in P.falciparum changed its sensitivity towards inhibitors [18].…”

“…Metyltetraprole (MTP) is a novel QoI that does not seem affected by the resistance mutation G143A [1][2][3]. The compound has a side-chain similar to that of the synthetic strobilurin pyraclostrobin, but has a unique tetrazolinone-moiety.…”

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

“…32 and Leptosphaeria maculans. 33 Although we previously showed that the microtiter plate test was useful in testing the metyltetraprole sensitivity of some fungal species, 3 we had not adopted this method to investigate C. beticola.…”

“…Metyltetraprole, 1–3 being developed under the trade name Pavecto®, is a new quinone outside inhibitor (QoI) that overcomes QoI‐resistant fungi harboring G143A or F129L mutations in cytochrome b ( Cytb ), which are very problematic for disease management in many crops 4 . Although metyltetraprole is very effective against current QoI‐resistant fungal populations, new genotypes of metyltetraprole‐resistant strains might emerge in the future.…”