Suyue Jing, Fadi Zhu, Xiaodong Wen, Jing Zhang, Gang Feng
{"title":"Effect of SHAM on the activity of coumoxystrobin against Phytophthora litchii","authors":"Suyue Jing, Fadi Zhu, Xiaodong Wen, Jing Zhang, Gang Feng","doi":"10.1007/s40858-024-00657-1","DOIUrl":null,"url":null,"abstract":"<p>Litchi downy blight, caused by <i>Phytophthora litchii</i>, presents significant challenges to litchi production, storage, and transportation. Previous studies have shown that coumoxystrobin exhibits effective inhibitory activity against <i>P</i>. <i>litchii</i>. Salicylhydroxamic acid (SHAM), an alternative respiratory pathway inhibitor, is commonly used to evaluate the efficacy of cytochrome respiratory pathway inhibitor like coumoxystrobin against fungal phytopathogens <i>in vitro</i>. In this study, the toxicity of SHAM on various developmental stages of <i>P</i>. <i>litchii</i>, including mycelial growth, sporangial germination, zoospore release, and cystospore germination, was assessed. The EC<sub>50</sub> values for SHAM were determined as 166.72, 150.69, 333.97, and 240.91 μg/mL, respectively. Subsequently, the activity of coumoxystrobin against <i>P</i>. <i>litchii</i> was assessed in the presence of SHAM at a concentration of 50 μg/mL, which showed slight inhibition below 20% for all four developmental stages. The addition of SHAM significantly improved the inhibitory activity of coumoxystrobin against <i>P</i>. <i>litchii</i> at different stages, with reductions in EC<sub>50</sub> values ranging from 7.55- to 122.92-fold. Moreover, respiration assays revealed that a concentration of 5 μg/mL coumoxystrobin inhibited <i>P</i>. <i>litchii</i> mycelial respiration to a lesser extent compared to the combined effect of coumoxystrobin and SHAM. SHAM also enhanced the control efficacy of coumoxystrobin against phytophthora blight development on litchi leaves. Previously, we reported that coumoxystrobin effectively controls postharvest downy mildew on litchi fruit. Consequently, coumoxystrobin holds promise as an agent for litchi downy blight control in the field and after harvest. Furthermore, similar to previous studies, SHAM, an alternative oxidase (AOX) inhibitor, was found to significantly enhance the activity of the two aforementioned QoI fungicides against <i>P</i>. <i>litchii</i>, both <i>in vitro</i> and <i>in vivo</i>. This suggests that further exploration of AOX inhibitors and the role of AOX in plant diseases could contribute to the rational use of QoI fungicides and improve control efficiency for plant diseases.</p>","PeriodicalId":23354,"journal":{"name":"Tropical Plant Pathology","volume":null,"pages":null},"PeriodicalIF":2.5000,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Tropical Plant Pathology","FirstCategoryId":"97","ListUrlMain":"https://doi.org/10.1007/s40858-024-00657-1","RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"Agricultural and Biological Sciences","Score":null,"Total":0}
引用次数: 0
Abstract
Litchi downy blight, caused by Phytophthora litchii, presents significant challenges to litchi production, storage, and transportation. Previous studies have shown that coumoxystrobin exhibits effective inhibitory activity against P. litchii. Salicylhydroxamic acid (SHAM), an alternative respiratory pathway inhibitor, is commonly used to evaluate the efficacy of cytochrome respiratory pathway inhibitor like coumoxystrobin against fungal phytopathogens in vitro. In this study, the toxicity of SHAM on various developmental stages of P. litchii, including mycelial growth, sporangial germination, zoospore release, and cystospore germination, was assessed. The EC50 values for SHAM were determined as 166.72, 150.69, 333.97, and 240.91 μg/mL, respectively. Subsequently, the activity of coumoxystrobin against P. litchii was assessed in the presence of SHAM at a concentration of 50 μg/mL, which showed slight inhibition below 20% for all four developmental stages. The addition of SHAM significantly improved the inhibitory activity of coumoxystrobin against P. litchii at different stages, with reductions in EC50 values ranging from 7.55- to 122.92-fold. Moreover, respiration assays revealed that a concentration of 5 μg/mL coumoxystrobin inhibited P. litchii mycelial respiration to a lesser extent compared to the combined effect of coumoxystrobin and SHAM. SHAM also enhanced the control efficacy of coumoxystrobin against phytophthora blight development on litchi leaves. Previously, we reported that coumoxystrobin effectively controls postharvest downy mildew on litchi fruit. Consequently, coumoxystrobin holds promise as an agent for litchi downy blight control in the field and after harvest. Furthermore, similar to previous studies, SHAM, an alternative oxidase (AOX) inhibitor, was found to significantly enhance the activity of the two aforementioned QoI fungicides against P. litchii, both in vitro and in vivo. This suggests that further exploration of AOX inhibitors and the role of AOX in plant diseases could contribute to the rational use of QoI fungicides and improve control efficiency for plant diseases.
期刊介绍:
Tropical Plant Pathology is an international journal devoted to publishing a wide range of research on fundamental and applied aspects of plant diseases of concern to agricultural, forest and ornamental crops from tropical and subtropical environments.
Submissions must report original research that provides new insights into the etiology and epidemiology of plant disease as well as population biology of plant pathogens, host-pathogen interactions, physiological and molecular plant pathology, and strategies to promote crop protection.
The journal considers for publication: original articles, short communications, reviews and letters to the editor. For more details please check the submission guidelines.
Founded in 1976, the journal is the official publication of the Brazilian Phytopathology Society.