As a highly valued fungus, Cordyceps militaris has been widely used all over the world. Although the wild resources of C. militaris are limited, the fruiting bodies of C. militaris have been successfully cultivated on a large-scale. However, the high-frequency degeneration of C. militaris during subculture and preservation seriously limits the development of the C. militaris industry. How to solve the degeneration of C. militaris has become an unsolved bottleneck problem throughout the whole Cordyceps industry. The aim of this review is to illustrate the phenotypic changes after the degeneration of C. militaris, focusing on the causes (including environmental factors and genetic variation) of C. militaris degeneration. Moreover, genetic variation is the root cause of the degeneration of C. militaris strains. Measures to prevent the degeneration of C. militaris are also discussed in this review. This paper will increase understanding of the degeneration mechanism of C. militaris, provide a reference for solving the degeneration problem of C. militaris, and lay a foundation for promoting the sustainable development of C. militaris.
Keywords: Cordyceps militaris; Degeneration mechanism; Filamentous fungi; Fruiting body; Genetic variation; Subculture.