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Ultrastructures of Colletotrichum orbiculare in Cucumber Leaves Expressing Systemic Acquired Resistance Mediated by Chlorella fusca
Published online February 1, 2018
© 2018 The Korean Society of Plant Pathology.

Su Jeung Kim1, Eun Ju Ko2, Jeum Kyu Hong3, and Yong Chull Jeun2,4*

1Biotech Center, Pohang University of Science and Technology, Pohang, Gyeongbuk 37673, Korea
2College of Applied Life Science, Sustainable Agriculture Research Institute, Jeju National University, Jeju 63243, Korea
3Department of Horticultural Science, Gyeongnam National University of Science and Technology (GNTech), Jinju52725, Korea
4The Research Institute for Subtropical Agriculture and Biotechnology, Jeju National University, Jeju 63604, Korea
Correspondence to: Phone) +82-64-754-3319, FAX) +82-64-754-2351
Received September 29, 2017; Revised December 28, 2017; Accepted December 28, 2017.
Chlorella, one single-cell green algae organism that lives autotrophically by photosynthesis, can directly suppress some plant diseases. The objective of this study was to determine whether pre-spraying with Chlorella fusca suspension could induce systemic acquired resistance (SAR) in cucumber plants against anthracnose caused by Colletotrichum orbiculare. In order to illustrate SAR induced by algae, infection structures in host cells were observed under a transmission electron microscope (TEM). Cytological changes as defense responses of host mesophyll cells such as accumulation of vesicles, formation of sheath around penetration hyphae, and thickness of cell wells adjoining with intracellular hyphae were demonstrated in cucumber leaves. Similar defense responses were also found in the plant pre-treated with DL-3-aminobutyric acid, another SAR priming agent. Images showed that defense response of host cells was scarcely observed in untreated leaf tissues. These cytological observations suggest that C. fusca could induce SAR against anthracnose in cucumber plants by activating defense responses of host cells.
Keywords : algae, anthracnose, DL-3-aminobutyric acid (BABA), infection structure, plant growth promoting rhizobacteria (PGPR)

February 2018, 34 (1)