First Report of Fruit Rot on Schisandra chinensis Caused by Penicillium glabrum and P. adametzii in China
Authors: Chen C. Q. , Zhi Y. , Gao J. 
Published: November 2012

Schisandra (Schisandra chinensis (Turcz.) Baill) is an important medicinal herb in China, which is mainly used for treatment of insomnia and memory decay. In September 2010, rot was observed on approximately 5% of the fruits during ripening of schisandra in several orchards at Linjiang City and Ji'an City, Jilin Province. Watery spots on infected fruits of schisandra appeared at the end of ripening, and then the fruits darkened in color, shrunk, and turned soft. The surface of the lesions became covered with masses of blue-green mycelium, conidiophores, and conidia under high humidity. To isolate the causal agent, conidia and conidiophores were suspended in sterile water and streaked onto the surface of potato dextrose agar (PDA). Single hyphal tips were then transferred to new PDA plates to be purified. The isolates were then cultured on CYA (Czapek yeast extract agar) and two kinds of strains (wwzqm1 and wwzqm2) were established based on differential growth rate, microscopic features, and colony color. Pathogenicity of each strain was tested on 25 healthy mature fruits of schisandra cv. Red Pearl by inoculating the fruit surface with a 15 μl conidial suspension (106 conidia/ml). Control fruits were treated with sterile water. Fruits were kept at 25°C and 90% relative humidity. After a 5-day incubation, symptoms described above were observed on all inoculated fruits, whereas all control fruits were symptomless. The causal agent was reisolated, confirming Koch's postulates. Strain wwzqm1 was identified as Penicillium glabrum (Wehmer) Westling on the basis of its morphology. Conidiophores arose from basal hyphae, with stipes smooth or finely roughened, 50.5 to 300.0 × 2.5 to 3.5 μm, penicillus monoverticillate, and bearing verticils of 8 to 12 phialides. Conidia were globose to subglobose, approximately 2.9 to 3.5 μm in diameter, with smooth or nearly smooth walls, and conidial chains in compact columns. Colonies grown for 7 days on CYA at 25°C attained a diameter of 32.4 to 39.1 mm, with the center of a deep bluish green, plane, velutinous, and heavily sporulated. Margin mycelium of the colony was white, with a yellowish brown under surface. Strain wwzqm2 was identified as P. adametzii K. M. Zalessky according to its morphological features with conidiophores born from funicolose hyphae, stipes smooth, 10.2 to 20.1 × 1.5 to 2.5 μm, penicillus monoverticillate, and bearing verticils of 4 to 6 phialides. Conidia were nearly globose to glubose, 2.0 to 2.7 μm in diameter, with smooth or finely roughened walls, and conidial chains loose and irregular. Colonies on CYA at 25°C for 7 days grew rather fast and reached a diameter of 50.3 to 60.2 mm, and were deep grayish green, near plane, floccose or funicolose, and heavily sporulated. Margin mycelium of the colony was white with a yellowish brown under surface (1). The internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) was amplified for wwzqm1 and wwzqm2 using primers ITS4/ITS5 and sequenced. BLASTn analysis of the 595 bp wwzqm1 (GenBank Accession No. JN887323) amplicon had 99% sequence identity with P. glabrum (DQ681321) and the 568 bp wwzqm2 amplicon (JN887322) had 99% sequence identity with P. adametzii (AF033401). To our knowledge, this is the first report of fruit rot on S. chinensis caused by P. glabrum and P. adametzii in China.

Reference: (1). H. Z. Kong. Penicillium et Teleomorphi Cognati. Flora Fungorum Sinicorum. Science Press, Beijing, 35:43, 2007.