| The Chinese caterpillar fungus is a rare Chinese herbal medicine that is a parasitic complex composed of the remains of the caterpillar and the fungal sexual stroma.The basic research on it is the basis of its artificial cultivation.There is close relationship between light and fungus growth.According to the current research,there is no research report on the effect of light on the growth and development of Chinese caterpillar fungus.In this study,the monosporial strain TZ8-1 of Chinese caterpillar fungus was isolated and identified as Ophiocordyceps sinensis by molecular identification.After that,the monosporial strain TZ8-1 was obtained in the dark treatment group(D),light treatment group for 3 days(L3),light treatment group for 10 days(L10)and light treatment group for 30 days(L30)by experimental design and culture.The effects of light on colony morphology,pigment deposition,colony fresh weight,colony dry weight,mycelial morphology and conidia number were observed and recorded.The effects of light on the content of polysaccharide,mannitol,urea,adenosine and cordycepin were determined.On this basis,the difference of gene expression in different light period were analyzed by transcriptome sequencing.On this basis,we analyzed the difference of gene expression in different light period by transcriptome sequencing,and verified the reliability of transcriptome data by qRT-PCR.The aim of this study is to fill the research blank of the effect of light on the growth and development of Chinese caterpillar fungus and to provide a preliminary light basis for the cultivation of Ophiocordyceps sinensis.The main results are as follows:1.The monosporial strain of Chinese caterpillar fungus was obtained,and it was identified as Ophiocordyceps sinensis with molecular identification.2.The biological characteristics of Ophiocordyceps sinensis at different period of light treatment were significantly different.The surface of the colony was covered with villous aerial hyphae,and there were yellowish brown ring aerial hyphae bands,the pigment deposition was significantly increased,the fresh weight of the colony was significantly decreased,the hyphae was significantly thinner,and the number of conidia was significantly increased.3.After light treatment,the content of mannitol in the mycelium of Ophiocordyceps sinensis had no significant difference,while the content of polysaccharide and urea were significantly decreased,and the content of adenosine and cordycepin were significantly increased.4.Transcriptome sequencing showed that the gene expression of Ophiocordyceps sinensis began to differ after 3 days of light treatment,reached the peak value after 10 days of light treatment,and tended to be stable after 30 days of light treatment.5.The number of down-regulated genes was about 5 times of that up-regulated genes after light treatment.The results of pair-to-pair comparison among different treatment groups showed that the difference of gene expression between L10-vs-D group was highest,with a total of 3250 significantly differentially expressed genes,while the difference of gene expression between L30-vs-L3 group was lowest,with a total of 647 significantly differentially expressed genes.6.Through functional annotation of differential genes,it was concluded that the light treatment had the greatest effect on the cellular structure and catalytic metabolism of Ophiocordyceps sinensis,and the key genes affecting the anabolic pathways such as polysaccharide,urea,adenosine and cordycepin were found.7.The results of qRT-PCR were consistent with the results of transcriptome sequencing,and the existence of photoreceptor genes CRYD,WC-1 and FRQ were verified,these were proved that the Ophiocordyceps sinensis has a photoreceptor system. |
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