Molecular Mechanism Of The Interaction Between Sclerotinia Sclerotiorum Hypovirulence-associated DNA Virus 1(SsHADV-1) And Its Insect Vector Lycoriella Ingenua

Lycoriella ingenua is a Diptera insect that feeds on fungi including Sclerotinia sclerotiorum.Previous studies have shown that reciprocal interactions exist between L.ingenua and Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1(SsHADV-1).SsHADV-1 could be replicated in L.ingenua and drive it as a mediator;while SsHADV-1 inhibited the synthesis of repellents(mushroom alcohol and octanone)of S.sclerotiorum,thus attracted female adults oviposited on virus-infected colonies.After eggs' hatching,the larva then fed on th virus-infected colony and acquired SsHADV-1;meanwhile,the egg production was significantly improved.In this study,In order to inverstigate this mechanism of reciprocal interaction,we extracted RNA samples from larvae and adults of L.ingenua before and after infection with SsHADV-1,and carried out RNA_Seq analysis.We also probed whether L.ingenua could acquire other viruses when feeding on virus-infected colonoies.Comparing to the SsHADV-1-free larva and adults of L.ingenua,the differentially expressed genes of SsHADV-1-infected larvae and adults were 558 and 819,respectively.We carried out both GO function analysis and KEGG pathway enrichment analysis,and found that the infection of SsHADV-1 mainly affected the genes and pathways related to the metabolism and growth of L.ingenua.The enrichment pathways in SsHADV-1-infected adults and SsHADV-1-infected larva were similar to each other.Gene-enriched pathways tha were significantly up-regulated including transmembrane transport,compound-bound signaling,transport and catabolism,and the immune system;while significantly down-regulated genes were enriched in catalytic activity,heterocyclic compound binding,hydrolase,oxidoreductase activity,lipid and amino acid metabolism,and carbohydrate metabolism.After being infected by SsHADV-1,ovarian development-related genes genes were up-regulated,which were consistent with the increase of the egg-bearing amount of the SsHADV-1-infected females.The expression of the immune-related genes was up-regulated,indicating that the virus infection could improve the immunity of L.ingenua.Furthermore,we found that seven olfactory related genes were significantly down-regulated,suggesting that SsHADV-1-infected femeales might ovisposit eggs on fungal colonies whether they could release heavy repellents(such as mushroom alcohol and octanone)or not.In order to clarify whether L.ingenua could acquire and transmit more viruses,the larva were fed on colononies of S.sclerotiorum strains Sh051,SX276 and WF-1 which were infected by various mycoviruses for virus transmission test.We found that L.ingenua could acquire 14 species of mycoviruses by feeding,meanwhile,three mycoviruses,namely Sclerotinia sclerootiorum RNA virus X(SsRVX),Sclerotinia sclerotiorum RNA virus W2(SsRVW2)and Sclerotinia sclerotiorum mitovirus 3(SsMV-3),could be transmited to S.sclerotiorum.These results suggested that L.ingenua could transmit RNA mycoviruses beside SsHADV-1.Briefly,in this study,we firstly investigated the differential expression of genes of genes in SsHADV-1-infected L.ingenua.It may enhance our undersanding on the reciprocal interaction between SsHADV-1 and L.ingenua;we also found that L.ingenua could transmite RNA mycoviruses.Furthermore,we identified several viral geneomic contigs from RNA_Seq data,and they may represent new viruses,By Blastn and Bliastp on NCBI,we found theses viruses may be grouped in the families,such as Alphaflexiviridae,Ascoviridae,Nudviridae,Retroviridae,Siphoviridae,Mimiviridae,Deltaflexiviridae and Poxviridae.Our findings may provide novel kenoweldege on understand the interaction between L.ingenua and SsHADV-1 ecologically;and it also may be benefit for efficient application of SsHADV-1 in field to control S.sclerotiorum dieseases.