Integrated enzymes activity and transcriptome reveal the effect of exogenous melatonin on the strain degeneration of Cordyceps militaris

As a valuable medicinal and edible fungus, Cordyceps militaris has been industrialized with broad development prospects. It contains a lot of bioactive compounds that are beneficial to our health. However, during artificial cultivation, strain degeneration is a challenge that inhibits the industrialization utility of C. militaris. Exogenous melatonin (MT) can scavenge for reactive oxygen species (ROS) in fungus and can alleviate strain degeneration. To establish the significance and molecular mechanisms of MT on strain degeneration, we investigated the third-generation strain (W5-3) of C. militaris via morphological, biochemical, and transcriptomic approaches under MT treatment. Morphological analyses revealed that colony angulation of C. militaris was significantly weakened, and the aerial hypha was reduced by 60 mu mol L-1 MT treatment. Biochemical analyses showed low levels of ROS and malondialdehyde (MDA), as well as increasing endogenous MT levels as exogenous MT increased. RNA-Seq revealed that compared with the control, several antioxidant enzyme-related genes were up-regulated under 60 mu mol L-1 MT treatment. Among them, glutathione s-transferase genes were up-regulated by a factor of 11.04. In addition, genes that are potentially involved in cordycepin, adenosine and active compound biosynthesis for the growth and development of mycelium were up-regulated. Collectively, these findings provide the basis for further elucidation of the molecular mechanisms involved in C. militaris strain degeneration.

Automated summary

Cordyceps militaris is a valuable medicinal and edible fungus with broad development prospects. Strain degeneration during artificial cultivation inhibits its industrialization utility, but exogenous melatonin (MT) treatment can alleviate this problem. In this study, the effects of MT treatment on the third-generation strain of C. militaris (W5-3) were investigated using morphological, biochemical, and transcriptomic approaches. The results showed that MT treatment weakened colony angulation and reduced aerial hypha, while decreasing ROS and MDA levels and increasing endogenous MT levels. RNA-Seq analysis revealed up-regulation of antioxidant enzyme-related genes and genes involved in active compound biosynthesis. These findings provide a foundation for further understanding the molecular mechanisms of C. militaris strain degeneration.