The Basic Function Of FMO Gene In I.cicadae

Cordyceps cicadae is famous as a traditional edible and medicinal fungi in China.Studies have shown that chemical components in C.cicadae could prevent and treat multiple diseases.Flavin-containing monooxygenase was first found in liver microsomes,and then its functions has been reported in yeast,mammals and plants.But its functions are still unclear in filamentous fungi.In this study,we used gene knockout,florescence complementation,phenotype observation and real-time fluorescence quantitative PCR to systematically analyze the role of Icfmo gene in Isaria cicadae(which is the asexual type of Cordyceps cicadae).The main results are as follows:(1)By comparing the growth of wild-type WT,mutant ΔFMO and complementary bacteria FMO-c(hereinafter referred to as WT,ΔFMO,FMO-c)on PDA medium,it was found that the colony diameter ofΔFMO was significantly larger than that of WT,FMO-c,however the number of aerial hyphae and spores were significantly reduced.And the conidia produced of ΔFMO was only 51% of WT.In the process of spore germination,the germination rate at 8 h was significantly lower than that of WT.It is suggested that the Icfmo gene is related to the growth,sporulation and germination of I.cicadae.(2)By comparing the growth of WT,ΔFMO and FMO-c on MM medium with different single carbon source,it was found that ΔFMO on sucrose,lactose,maltose and fructose medium significantly reduced the growth of aerial mycelium and colony diameter,but on starch medium,the growth them was significantly better than WT and FMO-c.It is suggested that Icfmo gene is related to carbon source utilization of I.cicadas(3)By comparing the growth of WT,ΔFMO and FMO-c on MM medium with H2O2,SDS,CFW and Congo red,it was found that there was no significant difference(or no growth)in the growth of them.It is suggested that the Icfmo gene is not related to the ability of cell wall formation and antioxidant stress of I.cicadas.(4)By comparing the hydrolysis circle size of WT,ΔFMO and FMO-c on different substrates and measuring the content of polysaccharide,cordycepic acid and adenosine,it was found that,ΔFMO was different from WT on the substrates of starch and Milk powder,but not on the substrates of chitin.And only polysaccharide was different from WT in the metabolites of ΔFMO.It is suggested that the Icfmo gene has a certain effect on the synthesis of protease,amylase and polysaccharide of I.cicadas.(5)The fruiting body of edible fungus is also the part that people can directly process and eat.Whether it can produce fruiting body is very important for the work of breeding edible fungus.We investigated whether three strains could produce fruiting bodies on flour medium and rice medium,and the results showed that the absence of Icfmo gene led to the abnormal formation of fruiting bodies,which indicated that Icfmo gene played a key role in the formation of fruiting bodies of I.cicadae.In addition,through the analysis of transcriptome,we found that Icfmo mainly affects sterol synthesis,tyrosine metabolism and nitrogen metabolism.In addition,only 15 genes are enriched in KEGG pathway,it showed that Icfmo gene may be in the downstream of metabolism pathway.Thus,the effect on other genes is relatively less.