Research On The Key Genes In The Triggering Of Stroma In Chinese Cordyceps Based On Transcriptome Analysis

Chinese cordyceps is a rare Chinese herbal medicine in China.The initiation and formation of stroma is a key factor in the growth of Chinese cordyceps,and the study on mechanism and change process during this period is the basis for artificial cultivation in Chinese cordyceps.There is little observation on the initiation of stroma in Chinese cordyceps so far as now.In this study,three stages of Chinese cordyceps were used as materials,including pre-germinate(the worm),at the beginning of germination(the mycelium broke through the head)and after germination(the formation of stroma).The scanning electron microscopy(SEM)was used to observe the morphological differences of the hyphae in three stages,changes in the contents of polyphenols,polysaccharides,mannitol,urea and adenosine during the growth process were detected,the gene expression at each stage during the germination process of the stroma was analyzed by transcriptome sequencing technology,which transcriptome data was further verified by q RT-PCR technology.Furthermore,the differences in the worm(H)metabolite chemicals during the germination process of the stroma and the metabolite chemicals of the worm body(H)during the germination of the stroma were analyzed by non-targeted metabolomics technology.The aim was to identify the key genes before and after the germination of the stroma and the main metabolites that regulated its emergence only at the head,which will lay the foundation for the intrinsic mechanism of artificial cultivation for Chinese cordyceps.The main results are as follows:1.The morphological variation of the mycelium at different growth stages during the germination of stroma in Chinese cordyceps were obvious.It showed that the mycelium starts to fuse before the germination of stroma,the mycelium was loose and slender when germinated,and the mycelium was uniform in thickness with the characteristics of micro-wart particles on the surface after germination.2.During the initiation and development of the stroma,the content of polyphenols and urea decreased significantly in Chinese cordyceps.The content of adenosine,polysaccharide and mannitol,however,increased with its growth.3.Transcriptome sequencing results show that the initial stage of stroma germination was the key stage in the triggering of Chinese cordyceps stroma.Tyrosine metabolism was up-regulated at this stage,and genes,related to stroma development,including rad R,MYB family gene(65E11.140),and cytochrome p450 gene(CYP205),were found differential expression.Validation by q RT-PCR confirmed that the transcriptome data were reliable in this experiment.4.Untargeted metabolomic analysis show that five compounds,L-proline,L-arginine and betaine and 2-hydroxycinnamic acid,were specific expressed in the pre-germination of the stroma in head of worm.