مقاله ۲۰۱۸: بیماری کپک سبز قارچ گانودرما

First Report of Trichoderma longibrachiatum Causing Green Mold Disease on Ganoderma lingzhi

Ganoderma lingzhi is a valuable herbal medicine in Asia. It is mostly cultivated in China, Japan, and South Korea. It is mainly used for prevention and treatment of nephritis, hypertension, and bronchitis, and it has antitumor properties (Nie et al. 2013; Paterson 2006; Wu et al. 2011). In 2015, the planting area of G. lingzhi was 100 million square meters in China (Jin et al. 2016). In the spring of 2015, rot disease symptoms were observed on the fruiting bodies of G. lingzhi with incidence of over 40% at the farm of Fushun city, Liaoning province, China. The main symptoms were spider-reticulated white mycelium under the G. lingzhi cap and green rot on the stipe. The disease was most severe during the sporulation of G. lingzhi. To isolate the disease-causing organism, fruiting bodies from the farm were surface sterilized in 75% ethanol for 30 s, washed three times with sterile distilled water, and cultured on potato dextrose agar. The Petri dish was covered by the purified mycelium, which was white arachnoid in 3 days. After 7 days, the gray-green conidia clustered into a gray-green heap, forming a pustular structure. Conidiophores unsymmetrical, Trichoderma-like, composing a conspicuous main axis with short side branches or phialides, branches unpaired. Phialides most solitary, 2.4 to 5.0 × 9.5 to 16 μm, 1.2 to 3.1 μm wide at the base. Conidia gray-green, smooth, elliptical, 2.8 to 5.0 × 2.0 to 2.5 μm. The morphological characteristics of isolate fungus were consistent with Trichoderma longibrachiatum (Wu et al. 2008). The rDNA internal transcribed spacer (ITS) and TEF1-α gene region were amplified (Carbone et al. 1999) and sequenced using ITS1/ITS4 and EF1-595F/EF1-1160R primers. As the BLAST analysis revealed, the amplified products (GenBank accession nos. MG894396 and MH348179, respectively) were found to be 100% identical with T. longibrachiatum. In the pathogenicity test, the inner surface of the G. lingzhi grown for 7 days was wiped with sterilized cotton soaked with the spores (1 × 106 conidia/ml) of the isolated strain. Sterile distilled water was applied as a negative control treatment. All treatments were carried out at 25°C and 85 to 90% humidity in the greenhouse. After 10 days, the white mycelium mantled the inner surface of fruiting bodies of G. lingzhi, forming gray-green colonies that caused green rot on the stipe. No symptoms were observed on the control, inoculated with sterile distilled water. The pathogen was reisolated from diseased issues as the method previously described, but not from controls. Based on morphological identification, molecular identification, and the pathogenicity assay, the pathogen was identified as T. longibrachiatum. T. longibrachiatum was reported to cause mold diseases in oyster mushroom (Choi et al. 2003). To our knowledge, this is the first report of T. longibrachiatum causing green rot disease on G. lingzhi. In view of the considerable impact of T. longibrachiatum on G. lingzhi, appropriate measures should be applied to prevent and control this disease.