title: Microscopical observation of inhibition-behaviors against Diaporthe citri by pre-treated with Pseudomonas putida strain THJ609-3 on the leaves of citrus plants.
abstract: Citrus melanose is one of the most important diseases in orchards cultivating citrus in the world. Although the disease does not cause yield loss, the profitability of the infected fruits is often reduced in the fresh-market, resulting in economic loss. In this study, disease reduction was proven by pre-treatment with Pseudomonas putida strain THJ609-3. In order to illustrate mechanism of the disease reduction by the bacterial strain, the infection behaviors of Diaporthe citri and necrosis deposit of plant tissue were observed using a fluorescence microscope. On the leaves pre-treated with the strain THJ609-3, germination rates of D. citri conidia were significantly decreased compared to those of the untreated control. Scanning electron microscopical observations showed that bacterial cells were attached to the surface of fungal hyphae. Furthermore, morphological change of germ tubes of the conidia was detected. These results suggest that the disease reduction may be caused by the direct antifungal activity of the bacterial strain on the leaf surfaces.
authors.affiliation: Major of Plant Resources and Environment, College of Applied Life Sciences, The Research Institute for Subtropical Agriculture and Biotechnology, Jeju National University, Jeju, 690-756, Republic of Korea.
authors.forename: Yun Jung
authors.initials: YJ
authors.lastname: Ko
authors.forename: Ju Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Ki Deok
authors.initials: KD
authors.lastname: Kim
authors.forename: Yong Chull
authors.initials: YC
authors.lastname: Jeun
mesh_terms: D000898:Antibiosis; D001203:Ascomycota / Q000254:growth & development* / Q000648:ultrastructure; D001422:Bacterial Adhesion; D002957:Citrus / Q000382:microbiology*; D025301:Hyphae / Q000254:growth & development / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control; D018515:Plant Leaves / Q000382:microbiology; D016958:Pseudomonas putida / Q000254:growth & development / Q000502:physiology*