Genetics Lab

Molecular Genetics Lab


The Sex-determination system of Cordyceps Militaris

In nature, there are two forms of reproduction: asexual and sexual. In asexual reproduction, an organism can reproduce without the involvement of another organism, creates a genetically similar or identical copy of itself. However, the evolution of sexual reproduction is a major puzzle for biologists. “Heterothallic”, the term is applied particularly to distinguish fungi which require two compatible partners to produce sexual spores. In contrast, Homothallic fungi are capable of sexual reproduction from a single organism. In the case of Cordyceps militaris, that is a large edible fungus and sexually reproducing species of Ascomycota.

Furthermore, Cordyceps militaris has two sex-determining loci, MAT1-1 (containing genes MAT1-1-1 and MAT1-1-2) and MAT1-2 (containing genes MAT1-2-1) located on the 7th chromosome. In particular, the genes MAT1-1-1 and MAT1-2-1 are transcription factors that regulate two pheromones genes PPG1 and PPG2, respectively. The gene products of PPG1 and PPG2 are pheromone precursors that can be modified to form pheromone capable of binding to a specific pheromone receptor on the surface of the heterosexual hyphae to recognize the opposite sex and to mate.


The ability analytics of Cordyceps Militaris

The reproduction of Cordyceps is mysterious and complex, highly triggered by environmental conditions. For example, the reproduction may occur in two well-differentiated stages within the life cycle, the anamorph state and the teleomorph state. Anamorph state occurred when deficient in nutrition, Conidia distributed by wind or water propagation to find a more suitable living space. While ripe Cordyceps Militaris reproduce like most fungi by spreading out the ascospores in the teleomorph stage.

On top of that, we identified the sexual of every single spore by analyzing the genes in sex-determining locus with polymerase chain reaction (PCR). Then grew the spores into hyphae, extracted the genes (mRNA) and reverse-transcribed into cDNA. Quantified the ability of each Cordyceps Militaris spore by real-time PCR and predicted the growth morphology, growth rate and the contents of various high-value nutrients such as cordycepin, cordycepic acid, cordyceps polysaccharide, GABA, etc. At last, select the spores with different characteristics for mating and breeding, the filial generation with advantages of parental generation, a potential new strain was successfully cultivated.