| Arthrobotrys oligospora is a typical nematode-trapping fungus.The lifestyle of A.oligospora is saprophytism without the induction of nematodes.However,under the induction of nematodes,A.oligospora can develop adhesive networks to capture nematodes.The formation of adhesive networks is also a key indication of transition from saprophytic lifestyle to parasitic lifestyle.This study uses the nematode extract to induce A.oligospora,and selects three key time points for transcriptional analysis,which include 0h,10h(early stage)and 48h(later stage).Systematic biological analysis reveals the change of gene expression during the formation of adhesive networks,and provides insights into the mechanism underlying the life style transition of A.oligospora.The results showed that 941 genes showed significant regulation in the early stage of induction from 0h to 10 h,of which the number of up-regulated genes was 496,and the number of down-regulated genes was 445.In the late stage of induction of 10 h to48h,the number of significantly regulated genes was 824,of which 459 were upregulated,and 365 genes were down-regulated.326 genes showed significant regulation during the whole induction process of 0h to 48 h,of which 192 showed up-regulation and 134 showed down-regulation.Totally,17 genes showed up-regulation in all the three stages,including ao0300022,ao0300211,ao0301042,ao0301264,ao0302655,ao0302756,ao0304428,ao0304464,ao0305286,ao0305588,ao0305659,ao0306455,ao0308399,ao0308807,ao0308988,ao0309139 and ao0309357,Four genes showed down-regulation throughout the process,including ao0300390,ao0303860,ao0307037 and ao0310212.The COG annotation of differentially expressed genes showed that the upregulated genes were mainly involved in post-translational modification,protein turnover(O),lipid transport and metabolism(I),biosynthesis of secondary metabolites,transport and catabolism(Q),and inorganic ion transport and metabolism(P)and other biological processes.The down-regulated genes were involved in the general functional prediction(R),carbohydrate transport and metabolism(G),amino acid transport and metabolism,inorganic ion transport and metabolism(P)and other biological processes.The GO annotation showed that the differentially expressed genes were mainly involved in redox process,transmembrane transport,protein hydrolysis,metabolicactivity and cell stress reaction.Their functions were related to protein binding,ATP binding,catalytic activity,oxidoreductase activity and the binding of metal ions,etc.In KEGG pathway analysis,we found that the up-regulated genes in the early stage of 0 to 10 h induction were mainly involved in the cell cycle and the ubiquitination system,and the down-regulated genes were mainly involved in glyoxylic acid and two formate ethylenediethylacyl metabolism,transshipment of egg white,glycolysis/carbohydrate freshmen and other pathways.In the late stage of 10 to 48 h induction,the up-regulated genes were mainly involved in pyruvate metabolism,ABC transporter,tryptophan metabolism,and fatty acid metabolism,while the down-regulated genes were mainly involved in steroid biosynthesis,transcription factors,pyruvate metabolism,glyoxylic acid and two formic acid ethylacyl metabolism and biological metabolism.In the whole process of the induction of 0 to 48 h,the up-regulated gene was mainly involved in the metabolism of lipid biosynthesis,transporter and starch and sucrose,and the down-regulated genes were mainly involved in the biosynthesis of ribosome,transporter,peptidase and phenylpropane.In this paper,a transcriptomic study was conducted to identify the differentially expressed genes during the induction of trapping devices of A.oligospora by the nematode.The results showed that a few biological processes and regulatory pathways were involved and may play an important role in the trap induction by functional annotation,which provide new insights into understanding the mechanism underlying the lifestyle transition of nematode-trapping fungi. |
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