HomePlant DiseaseVol. 101, No. 8First Report of Penicillium brevicompactum Causing Blue Mold Disease of Grifola frondosa in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Penicillium brevicompactum Causing Blue Mold Disease of Grifola frondosa in ChinaF. H. Tian, C. T. Li, and Y. LiF. H. TianSearch for more papers by this author, C. T. LiSearch for more papers by this author, and Y. LiSearch for more papers by this authorAffiliationsAuthors and Affiliations F. H. Tian C. T. Li Y. Li , Engineering Research Center of Chinese Ministry of Education for Edible and Medicinal Fungi, Jilin Agricultural University, Changchun, Jilin Province 130118; P.R. China. Published Online:2 Jun 2017https://doi.org/10.1094/PDIS-09-16-1301-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Grifola frondosa (Dicks.) Gray (Maitake) is known for its high nutrition and medicinal properties. In China, it is predominantly grown in the northeastern and southeastern parts. It sustains the livelihoods of many small-scale farmers in Asia and other parts of the world where it is cropped or traded. In May 2015 and June 2016, serious blue mold epidemic occurred on many mushroom farms in Changchun (Jilin Province) and Qingyuan (Zhejiang Province), China. The infected mycelia and fruiting bodies of G. frondosa in cultivated bags became yellow, wilted with yellow water drop secretion, and growth was inhibited, leading to eventual death. The surfaces of the cultivated bags were covered with grayish-green fungal colonies. Once this occurred, the infected mycelia were not able to generate fruiting bodies, and even if fruiting bodies were generated, their growth was stunted or they spread disease to adjacent ones. Samples were collected and sterilized using 0.1% NaClO solution and rinsed three times with sterilized distilled water. It was then plated on four different media, Czapek agar (CA), Czapek yeast autolysate agar (CYA), malt extract agar (MEA), and potato dextrose agar (PDA) supplemented with 0.1M Kanamycin. Colonies on PDA grew slowly, 10 mm in diameter at 25°C and 55 to 60% relative humidity in mold cultivation cabinet within 7 days. The colony was slightly umbonate at center, and radially sulcate. Grayish green conidia were formed on the whole surface of the colonies. Penicilli were most terverticillate. The conidiophore wall was smooth. Metulae were cylindrical, 9.31 to 18.52 × 2.36 to 4.09 μm, in verticils of 3 to 6. Phialides were ampulliform, 8.63 to 18.52 × 2.48 to 4.04 μm, in verticils of 2 to 6. Conidia were spheroidal to ellipsoidal, 3.5 to 4.8 × 3.3 to 4.6 μm, with smooth to roughened walls. The internal transcribed spacer (ITS) region, the second largest subunit of RNA polymerase II (RPB2) gene, and cauliflower (CAL) gene were amplified with primers ITS1/ITS4, RPB2-740F/1365R, and CAL-228F/737R, respectively. Nucleotide alignment showed 99% sequence identity (ITS) with Penicillium brevicompactum (LN808902); 99% sequence identity (RPB2) with P. brevicompactum (LN833569), and 98% sequence identity (CAL) with P. brevicompactum (AY484821). Based on the morphological characteristics, cultural traits, and the sequences of ITS, RPB2, and CAL of the isolation, the fungus was identified as P. brevicompactum. To confirm pathogenicity, modified Koch’s postulates were achieved as following: six repeated bags of G. frondosa for each different growth period were sprayed with 1 ml conidial suspension (106 conidia/ml); another three bags used sterilized water as control. All treatments were maintained at 18 to 19°C and 85 to 90% relative humidity in the same mushroom-growing space. The pathogen was consistently reisolated from the infected fruiting bodies of G. frondosa. All experiments were in triplicate. P. brevicompactum has been reported to the cause of postharvest fruit spoilage (Louw and Korsten 2014) diseases in plants (Valdez et al. 2009) and mushroom production (Qin et al. 2013; Zhu et al. 2016). To our knowledge, this is the first report of P. brevicompactum causing blue mold disease on cultivated G. frondosa. Effective measures need to be adopted to control this pathogen in order to prevent great losses to farmers.