title: Sclerotial formation of Polyporus umbellatus by low temperature treatment under artificial conditions.
abstract: BACKGROUND
  Polyporus umbellatus sclerotia have been used as a diuretic agent in China for over two thousand years. A shortage of the natural P. umbellatus has prompted researchers to induce sclerotial formation in the laboratory.
  
  
  RESULTS
  P. umbellatus cultivation in a sawdust-based substrate was investigated to evaluate the effect of low temperature conditions on sclerotial formation. A phenol-sulfuric acid method was employed to determine the polysaccharide content of wild P. umbellatus sclerotia and mycelia and sclerotia grown in low-temperature treatments. In addition, reactive oxygen species (ROS) content, expressed as the fluorescence intensity of mycelia during sclerotial differentiation was determined. Analysis of ROS generation and sclerotial formation in mycelia after treatment with the antioxidants such as diphenyleneiodonium chloride (DPI), apocynin (Apo), or vitamin C were studied. Furthermore, macroscopic and microscopic characteristics of sclerotial differentiation were observed. Sclerotia were not induced by continuous cultivation at 25°C. The polysaccharide content of the artificial sclerotia is 78% of that of wild sclerotia. In the low-temperature treatment group, the fluorescent intensity of ROS was higher than that of the room temperature (25°C) group which did not induce sclerotial formation all through the cultivation. The antioxidants DPI and Apo reduced ROS levels and did not induce sclerotial formation. Although the concentration-dependent effects of vitamin C (5-15 mg mL(-1)) also reduced ROS generation and inhibited sclerotial formation, using a low concentration of vitamin C (1 mg mL(-1)) successfully induced sclerotial differentiation and increased ROS production.
  
  
  CONCLUSIONS
  Exposure to low temperatures induced P. umbellatus sclerotial morphogenesis during cultivation. Low temperature treatment enhanced ROS in mycelia, which may be important in triggering sclerotial differentiation in P. umbellatus. Moreover, the application of antioxidants impaired ROS generation and inhibited sclerotial formation. Our findings may help to provide new insights into the biological mechanisms underlying sclerotial morphogenesis in P. umbellatus.
authors: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, People's Republic of China.
authors: Yong-Mei
authors: YM
authors: Xing
authors: Li-Chun
authors: LC
authors: Zhang
authors: Han-Qiao
authors: HQ
authors: Liang
authors: Jing
authors: J
authors: Lv
authors: Chao
authors: C
authors: Song
authors: Shun-Xing
authors: SX
authors: Guo
authors: Chun-Lan
authors: CL
authors: Wang
authors: Tae-Soo
authors: TS
authors: Lee
authors: Min-Woong
authors: MW
authors: Lee
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D025282:Mycelium / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D016612:Paraffin Embedding; D055492:Polyporus / Q000166:cytology / Q000187:drug effects / Q000254:growth & development* / Q000648:ultrastructure; D011134:Polysaccharides / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013696:Temperature; D013997:Time Factors
chemical_list: D000975:Antioxidants; D011134:Polysaccharides; D017382:Reactive Oxygen Species