The G143A/S substitution of mitochondrially encoded cytochrome b (Cytb) in Magnaporthe oryzae confers resistance to quinone outside inhibitors. Issue 11 (18th August 2022)

• Record Type: Journal Article
• Authors: Li, Tao; Xu, Jinke; Gao, Han; Cao, Zhiguo; Wang, Jianxin; Cai, Yiqiang; Duan, Yabing; Zhou, Mingguo
• Is Part Of: Pest management science. Volume 78:Issue 11(2022)
• Page Start: 4850
• Page End: 4858
• Publication Date: 2022-08-18
• Subjects: Magnaporthe oryzae -- picoxystrobin -- sensitivity -- mutation -- cross‐resistance; Pests -- Control -- Periodicals; Pesticides -- Periodicals; 632.9
• DOI: 10.1002/ps.7106
• Languages: English
• ISSNs: 1526-498X

Abstract

Abstract: BACKGROUND: Rice blast, caused by Magnaporthe oryzae, is a destructive disease threatening the production of staple foods worldwide. Quinone outside inhibitors (QoIs) are a group of chemicals exhibiting excellent activity against a majority of plant pathogens, with the disadvantage that pathogens can easily develop resistance to QoIs. RESULTS: Here, we investigated the activity of picoxystrobin against M. oryzae, which showed a great inhibitory effect on 100 strains of M. oryzae with half‐maximal effective concentrations (EC50 ) ranging from 0.0251 to 0.1337 μg ml −1 . The EC50 values showed a continuous unimodal distribution that was identical to the normal distribution, suggesting the potency of our study to represent baseline sensitivity. In addition, nine resistant mutants were obtained by exposing M. oryzae to a high dosage of picoxystrobin in the laboratory; all of them showed cross‐resistance to the other five QoI fungicides. Although some mutants showed a decreased resistance factor after ten successive cultures on fungicide‐free medium, the resistance to picoxystrobin was still inheritable. Amino acid substitution of G143S was detected in eight of nine picoxystrobin‐resistant mutants, and G143A was detected in only one of nine mutants. A fitness penalty was found in the mutants carrying G143S rather than G143A. CONCLUSION: Our findings suggested that M. oryzae had a mid to high risk of resistance to picoxystrobin. Considering this, we should be vigilant to the resistance risk and apply picoxystrobin sensibly in the field. © 2022 Society of Chemical Industry. Abstract : The M. oryzae mutants with G143A/S substitution in Mocytb confers resistance to picoxystrobin and the substitutions altered the binding pocket of picoxystrobin to Mocytb and decreased the binding affinity.