Genotypic analysis of degenerativeCordyceps militariscultured in the pupa ofBombyx mori
2018
Juan YIN, Jiangsu University of Science and Technology, Zhenjiang, China | Xiang-Dong XIN, Jiangsu University of Science and Technology, Zhenjiang, China | Yu-JieWENG, Jiangsu University of Science and Technology, Zhenjiang, China | Shao-Hui LI, Jiangsu University of Science and Technology, Zhenjiang, China | Jun-Qiang JIA, Jiangsu University of Science and Technology, Zhenjiang, China | Zhong-Zheng GUI, Jiangsu University of Science and Technology, Zhenjiang, China
The chemical composition and pharmacological effects ofCordyceps militarisaresimilar to those ofCordyceps sinensis,with the former undergoing greaterdevelopment and utilization. Straindegeneration is a common phenomenon thatoccurs with high frequency during the subculturing ofC. militaris, however, and themechanism underlying strain degeneration remains unclear. In this study, we usedtouch-down PCR to compare the ITS1 + 5.8S + ITS2, 18S, 28S and mating-type(MAT) regions sequence of wild-type and degenerated strains ofC. militaris.Wealsoused quantitative real-time PCR toanalyze expression levels of theCmMATgene.Sequence analysis showed that the ITS1 + 5.8S + ITS2 and 28S regions of degeneratedand wild-type strains were completely identical, the 18S region of the degeneratedstrain contained seven single-base mutations, including six base substitutions andone single-base insertion. Compared with the wild-type strain, the degenerated straincontained a deletion of the MAT1-2-1 region, three base substitutions in theMAT1-1-1 region, and a base substitution in the MAT1-1-2regionthatcausesaglycine-to-valine amino acid substitution. Quantitative real-time PCR analysisdetected noCmMAT1-2-1gene expression in the degenerated strain, confirming thedeletion of theCmMAT1-2-1gene. Expression levels of theCmMAT1-1-1andCmMAT1-1-2genes were significantly down-regulatedtoonly7.5%and4.4%,respectively, that of the wild-type strain. These results indicate that 18S and MATregion mutations, as well as down-regulated ofCmMATgene expression levels, mayplay important roles inC. militarisdegeneration. This study provides a theoreticalbasis for further elucidationof the molecular mechanisms ofC. militarisdegeneration.
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