title: Antifungal activity of various essential oils against Rhizoctonia solani and Macrophomina phaseolina as major bean pathogens.
abstract: OBJECTIVE
  The main objective of this study was to investigate the effect of various essential oils (EOs) to decrease the activity of cell wall degrading enzymes (CWDEs) produced by fungal phytopathogens, which are associated with disease progress. Also, effect of seed treatment and foliar application of peppermint EO and its main constituent, menthol, on diseases caused by two necrotrophic pathogens on bean was investigated.
  
  
  RESULTS
  Antifungal activity of EOs on Rhizoctonia solani and Macrophomina phaseolina, as bean pathogens, was evaluated. The EOs of Mentha piperita, Bunium persicum and Thymus vulgaris revealed the highest antifungal activity against fungi. The EO of M. piperita had the lowest minimum inhibitory concentration (MIC) for R. solani among the three EOs tested. This pathogen did not grow in the presence of M. piperita, B. persicum and T. vulgaris EOs at 850, 1200 and 1100 ppm concentrations, respectively. The B. persicum EO had the lowest MIC for M. phaseolina as this fungus did not grow in the presence of M. piperita, B. persicum and T. vulgaris EOs at concentrations of 975, 950 and 1150 ppm, respectively. Hyphae exposed to EOs showed structural changes. Activities of cellulase and pectinase, as main CWDEs of pathogens, decreased by EOs at low concentration without effect on fungal growth. Seed treatment and foliar application of peppermint EO and/or menthol significantly reduced the development of bean diseases caused by both fungi. Higher capability of menthol than peppermint EO in decreasing diseases on bean was observed.
  
  
  CONCLUSIONS
  Reducing CDWEs activity is a mechanism of EOs' effect on fungi. Higher antifungal activity of menthol compared to peppermint EO was observed not only in vitro but also in vivo.
  
  
  CONCLUSIONS
  Effect of EOs on CWDEs involved in pathogenesis is described in this study for the first time. Menthol can be used as a botanical fungicide to control destructive fungal diseases on bean.
authors.affiliation: Department of Crop Protection, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
authors.forename: N
authors.initials: N
authors.lastname: Khaledi
authors.forename: P
authors.initials: P
authors.lastname: Taheri
authors.forename: S
authors.initials: S
authors.lastname: Tarighi
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology*; D001203:Ascomycota / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D008610:Menthol / Q000494:pharmacology; D025282:Mycelium / Q000187:drug effects / Q000254:growth & development; D009822:Oils, Volatile / Q000737:chemistry / Q000494:pharmacology*; D010935:Plant Diseases / Q000517:prevention & control; D012232:Rhizoctonia / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development
chemical_list: D000935:Antifungal Agents; D009822:Oils, Volatile; D008610:Menthol
keywords: Bunium persicum; Macrophomina phaseolina; Mentha piperita; Rhizoctonia solani; Thymus vulgaris; cellulose; essential oil; menthol; pectinase