Effects Of Fungi Fibulorhizoctonia Sp. On The Expression Of Laccase-related Genes In The Reticulitermes

In nature,there is a close relationship between termites and fungi,such as symbiotic relationships,parasitic relationships,and pathogenic relationships.In this study,we learned that R.labralis and R.chinensis carried Fibulorhizoctonia sp.fungi into their nests,but R.aculabialis won't do this.In order to explore the purpose of workers collecting Fibulorhizoctonia sp.fungi,this study revealed the development of sclerotia in termite nests and the behavior of workers feeding hyphae;completed R.labralis,R.chinensis,and R.aculabialis workers and the transcriptome of its gut microbiota,analyzed the expression of enzyme-related genes for the degradation of lignin by these three termite workers.When compared the presence of sclerotia and not presence of sclerotia in the nest,the expression level of the enzyme-related gene of lignin were reduced by workers,and the reasons affected the sclerotia of termite were discussed.The main results and conclusions of this study include:1.Developmental study of sclerotia in termite nests revealed that Fibulorhizoctonia sp.fungi did not produce new sclerotia in termite nests.We observed that the Fibulorhizoctonia sp.fungi was carried into the termite nest by the R.labralis and R.chinensis,and was placed together with the termite eggs.In the nest of R.labralis,we found the sclerotium of the germinated hyphae,but the hyphae disappeared quickly.It indicates that the sclerotia can germinate hyphae in the termite nest,and the hyphae were fed by termites.After the sclerotia was moved into the nest by R.labralis and R.chinensis for 7 months,we found the sclerotia discarded in the termite nest.The discarded sclerotia is scattered throughout the termite nest,and the sclerotia is wrapped by termite excrement.It was observed that the sclerotia had only a brown shell,the sclerotia was hollow,and the internal hyphae disappeared completely.2.Experiments in which termites feed on hyphae indicate that the workers move the sclerotia into the nest in order to feed the hyphae of the sclerotia.The sclerotia of the germinated mycelium was placed in the nest of R.chinensis,and the number of hyphae decreased after 24 hours.The sclerotium of the germinating hyphae and the hyphae ball composed of the hyphae were placed simultaneously in the R.labralis nest.And it was found that the termites were surrounded by the hyphae ball most of the time.Put the sclerotia of the germinated mycelium dyed by the Congo red solution into the R.labralis nest.Congo red appeared in the digestive tract of termites after twenty-four hours,and the abdomen of the termites was red.This result proves that termites will feed hyphae,which is one of the reasons why termites move sclerotia from out of the nest to the nest.3.The transcriptome sequencing of three species of termite worker with their intestinal microbes were carried out.Each transcriptome received more than 11 G of data.RAW assembled 208,242 Unigenes,RCW assembled 242,801 Unigenes,and RLW assembled274,060 Unigenes.The transcriptomes of three species of termite workers were compared to the four databases(Nr,Swissprot,KEGG,and KOG)by the BLASTX program,and R.aculabialis workers were annotated to 71,838 Unigene,and R.chinensis workers were annotated to 97,257 Unigenes.The transcriptome of R.labralis workers were annotated to83,709 Unigenes.Transcriptome analysis revealed that the three enzymes that metabolize lignin were only laccase.In RAW,we found 4 laccase-related genes expression;9laccase-related genes expression in RCW;and 9 laccase-related genes expression in RLW.4.qRT-PCR was used to analyze the differential expression of 10 laccase related genes in the three termites.The results showed that 8 laccase genes were significantly higher in the R.aculabialis than in the other two species worker(P<0.05),the relative expression level of the laccase gene of the R.aculabialis was 28 times higher than that of the R.labralis,and 25 times that of the R.chinensis.Only two pairs of laccase-related genes were expressed in the R.aculabialis of the other two termites.Therefore,the expression level of the enzyme gene for lignin degradation in the R.aculabialis is higher than that of the R.labralis and R.chinensis.5.There are differences in the expression levels of 12 laccase genes in the workers when there appeared sclerotia and not appeared sclerotia in the nest.The results showed that the expression level of 11 laccase genes in workers with Fibulorhizoctonia sp.fungi was significantly higher than that in the nest without sclerotia(P<0.05),Among them,the expression level of laccase 1(Unigene 0023066)gene in worker ants with sclerotia was 3.6 times higher than that without sclerotia;The expression level of only one laccase gene was not significantly different in the workers when there were sclerotia in the nest and without sclerotia.In the R.chinensis,when there were sclerotia in the nest,the expression level of 10 laccase genes was significantly higher than that in the nest without sclerotia(P<0.05).Among them,the expression level of laccase 1(Unigene 0041878)gene in worker ants with sclerotia was 5.4 times higher than that without sclerotia.There was not significant difference between the two laccase genes with and without sclerotia in workers.In summary,Fibulorhizoctonia sp.fungi are beneficial to R.labralis and R.chinensis.It is speculated that these two kinds of termites will feed on the germinated mycelia of sclerotium to improve the efficiency of lignin degradation due to insufficient lignin-degrading enzymes secreted by themselves.Different species of termites have different ability to utilize Fibulorhizoctonia sp.fungi.