Yoshida S, Koitabashi M, Nakamura J, Fukuoka T, Sakai H, Abe M, Kitamoto D, Kitamoto H
Biofunction Division, National Institute for Agro-Environmental Sciences, Tsukuba, Japan.
Faculty of Science and Technology, Tokyo University of Science, Noda, Japan.
J Appl Microbiol. 2015 Jul;119(1):215-24. doi: 10.1111/jam.12832. Epub 2015 May 19.
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.
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.
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.
This study provides significant evidence of the potential for MELs to be used as novel agricultural chemical pesticides.
研究甘露糖赤藓糖醇脂（MELs）对固体表面疏水性的影响、其对几种植物病原真菌分生孢子早期侵染行为的抑制活性，以及对真菌寄主植物叶片病害发生的抑制活性。
基于放置在表面的水滴接触角的变化，评估了用MEL溶液（MEL - A、MEL - B、MEL - C和异MEL - B）和合成表面活性剂溶液处理后塑料薄膜表面疏水性的变化。经MEL处理的表面上的液滴角度在放置后100秒内被证实减小，接触角与吐温20处理的表面上观察到的相似，表明MEL处理后表面疏水性降低。接下来，在经表面活性剂溶液预处理的塑料表面上评估了禾本科布氏白粉菌、炭疽菌、围小丛壳菌和稻瘟病菌的分生孢子萌发、芽管伸长和附着胞的形成。在MEL处理的塑料薄膜表面上，虽然效果水平取决于真菌种类和MEL类型的组合，但倾向于观察到分生孢子萌发、芽管伸长受到抑制以及附着胞形成受到抑制。接种试验表明，在用MEL处理的小麦叶片切段上，由禾本科布氏白粉菌引起的白粉病症状得到了显著抑制。
MELs在降低固体表面疏水性方面表现出卓越能力，并且有可能抑制小麦植株中的白粉病，推测这是由于其对分生孢子萌发的抑制作用。
本研究为MELs用作新型农用化学农药的潜力提供了重要证据。
