title: Effects of biosurfactants, mannosylerythritol lipids, on the hydrophobicity of solid surfaces and infection behaviours of plant pathogenic fungi.
abstract: OBJECTIVE
  To investigate the effects of mannosylerythritol lipids (MELs) on the hydrophobicity of solid surfaces, their suppressive activity against the early infection behaviours of several phytopathogenic fungal conidia, and their suppressive activity against disease occurrences on fungal host plant leaves.
  
  
  RESULTS
  The changes in the hydrophobicity of plastic film surfaces resulting from treatments with MEL solutions (MEL-A, MEL-B, MEL-C and isoMEL-B) and synthetic surfactant solutions were evaluated based on the changes in contact angles of water droplets placed on the surfaces. The droplet angles on surfaces treated with MELs were verified to decrease within 100 s after placement, with contact angles similar to those observed on Tween 20-treated surfaces, indicating decreases in surface hydrophobicity after MEL treatments. Next, conidial germination, germ tube elongation and the formation of appressorium of Blumeria graminis f. sp. tritici, Colletotrichum dematium, Glomerella cingulata and Magnaporthe grisea were evaluated on plastic surfaces that were pretreated with surfactant solutions. On the surfaces of MEL-treated plastic film, inhibition of conidial germination, germ tube elongation, and suppression of appressoria formation tended to be observed, although the level of effect was dependent on the combination of fungal species and type of MEL. Inoculation tests revealed that the powdery mildew symptom caused by B. graminis f. sp. tritici was significantly suppressed on wheat leaf segments treated with MELs.
  
  
  CONCLUSIONS
  MELs exhibited superior abilities in reducing the hydrophobicity of solid surfaces, and have the potential to suppress powdery mildew in wheat plants, presumably due to the inhibition of conidial germination.
  
  
  CONCLUSIONS
  This study provides significant evidence of the potential for MELs to be used as novel agricultural chemical pesticides.
authors.affiliation: Biofunction Division, National Institute for Agro-Environmental Sciences, Tsukuba, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Yoshida
authors.affiliation: Biofunction Division, National Institute for Agro-Environmental Sciences, Tsukuba, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Koitabashi
authors.affiliation: Faculty of Science and Technology, Tokyo University of Science, Noda, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Nakamura
authors.affiliation: Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Fukuoka
authors.affiliation: Faculty of Science and Technology, Tokyo University of Science, Noda, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sakai
authors.affiliation: Faculty of Science and Technology, Tokyo University of Science, Noda, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Abe
authors.affiliation: Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Kitamoto
authors.affiliation: Biofunction Division, National Institute for Agro-Environmental Sciences, Tsukuba, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kitamoto
mesh_terms: D001203:Ascomycota / Q000737:chemistry* / Q000187:drug effects / Q000254:growth & development / Q000472:pathogenicity; D006017:Glycolipids / Q000494:pharmacology*; D057927:Hydrophobic and Hydrophilic Interactions; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D013172:Spores, Fungal / Q000737:chemistry / Q000187:drug effects / Q000254:growth & development; D013501:Surface-Active Agents / Q000494:pharmacology*; D014908:Triticum / Q000382:microbiology*; D014774:Virulence / Q000187:drug effects
chemical_list: D006017:Glycolipids; D013501:Surface-Active Agents; C439671:mannosylerythritol lipid
keywords: Blumeria graminis f. sp. tritici; Colletotrichum dematium; Glomerella cingulata; Magnaporthe grisea; anthracnose; mannosylerythritol lipids; powdery mildew; rice blast