Abstract

Oak wilt disease caused by Raffaelea quercus-mongolicae has emerged obviously in Korea. We selected antifungal isolates against R. quercus-mongolicae among 368 endophytic fungal isolates from different parts of oak and pine trees. The experiment was conducted in the primary and secondary screenings by dual culture test. The antifungal activity of the selected isolates was assessed in culture filtrate test based on the inhibition rates in mycelial growth, sporulation, and spore germination of oak wilt fungus. Five isolates, E089, E199, E282, E409 and E415, showed strong antifungal activity in culture filtrate test, and their antifungal activity decreased on the culture media supplemented with heated culture filtrate. Higher mycelial growth inhibitions on the unheated media were recorded in E409 (Colletotrichum acutatum), E089 (Daldinia childiae), E415 (Alternaria alternata) and E199 (Daldinia childiae) with the inhibition rates of 79.0%, 70.1%, 68.9% and 64.5%, respectively. These isolates also had the higher sporulation inhibitions on unheated media with the rates of 96.8%, 84.2%, 82.8% and 80.5%, respectively. The spore germination of the oak wilt fungus was completely inhibited by E282 (Nectria balsamea) on both unheated and heated media. These results showed that a higher number of potent antifungal isolates against oak wilt fungus was isolated from the petiole compared to the other parts. This study could contribute to the development of biological control approaches for the management of oak wilt disease caused by R. quercus-mongolicae.

摘要

在韩国，由桔梗蒙古栎引起的橡树枯萎病已明显出现。我们选择了针对蒙古栎的抗真菌菌株橡树和松树不同部位的368种内生真菌分离物中。该实验在双重培养试验的初次和二次筛选中进行。在培养滤液测试中，根据对橡树枯萎真菌的菌丝生长，孢子形成和孢子萌发的抑制率，评估了所选菌株的抗真菌活性。五种分离株，E089，E199，E282，E409和E415在培养滤液测试中显示出较强的抗真菌活性，并且在补充有加热培养滤液的培养基上，其抗真菌活性降低。在未加热的炭疽菌（Colletotrichum acutatum），E089（Daldinia childiae），E415（Alternaria alternata）和E199（E199Daldinia childiae）的抑制率分别为79.0％，70.1％，68.9％和64.5％。这些分离株在未加热的培养基上也具有较高的孢子形成抑制率，分别为96.8％，84.2％，82.8％和80.5％。橡木枯萎真菌的孢子萌发在未加热和已加热的培养基上均被E282（Balsamea Nectria）完全抑制。这些结果表明，与其他部位相比，从叶柄中分离出了更多的针对橡树枯萎真菌的有效抗真菌分离物。这项研究可能有助于开发生物防治方法，以解决由蒙古栎引起的橡树枯萎病。