Preliminary Study On The Functions Of Acetytransferase Rtt109 In Aspergillus Flavus

Aspergillus flavus is a common decay naturally filamentous fungi,producing a kind of high toxicity,carcinogenicity natural contaminants named aflatoxins during its growth process.Aflatoxins can contaminate food crops,causing huge losses to agricultural economy.Inaddition,Aspergillus flavus is the second largest pathogen in invasive aspergillosis,which is a great health threat to animals and humanbeings with extremelyhigh teratogenic rate,carcinogenic rate and fatality rate.With the development of the society,food and human health are becoming of increasingly great important,and so is prevention and treatment of Aspergillus flavus.In recent years,the study of histone acetylation in fungi has been carried out,and it is found that acetylation has played an important role in various physiological activities of different fungi.In this stufy,we used Aspergillus flavus as experimental material,and constructed acetyltransferase gene rtt109 knockout strain and its compensation strain by homologous recombination.The growth of?rtt109 was significantly suppressed compared to wild type strain and the compensation strain.Also the acervulus of ?rtt109 grew smaller,thus the amount of conidiums of ?rtt109 was significantly reduced,especialy the conidiums produced on YES solid medium are almost none.On one hand,the aflatoxins synthesised by ?rtt109 that had been cultured in PDB liquid medium for 3?6 d,was significantly decreased.On the other hand,the amount of sclerotia generated by ?rtt109 that cultured either under the light or dark had significantly reduced.We also found that the ?rtt109 strain could be extremely sensitive to DNA damage stress,while it showed slight response to osmotic stress,oxidative stress,cell wall stress.Through the maize infection experiment,we found that the rate of transplanting of ?rtt109 on the surface of affected niblet was largly reduced,and the aerial mycelium decreased significantly,which was consistent with the experiment results on the artificial medium.According to the Western blot results,it wass indicated that Rtt109 played a role of acetylation targeting H3K9 and H3K56.Then we constructed point mutantion strains of H3K9,one of the target site of Rtt109.Through phenotypic results and qRT-PCR results,we found that acetylation on H3K9 played an important role on growth,conidium,toxin synthesis,generateing of sclerotia,and infection in Aspergillus flavus.High level acetylation of H3K9 maintained the normal physiological activity of Aspergillus flavus,on the contract,low level acetylation of H3K9 suppressed it.However,the acetylation of H3K9 had no significant effect on Aspergillus flavus responsing to different environmental stresses.In conclusion,we preliminary studied the function of Aspergillus flavus acetyltransferase Rtt109,and it is found that Rtt109 participated in the Aspergillus flavus's growth,conidium formation,generation of sclerotia,synthesis of aflatoxins,responsing to environmental stresses,regulation of infection,and other life processes.We further found that it was the acetylation of H3K9 that influenced Aspergillus flavus's functions,but has no obvious influence on the environment stress response.The results fromm this study of rtt109 provided a data basis of acetylation regulating the growth of Aspergillus flavus,synthesis of aflatoxins,response to environmental stresses,and other life processes,and provides a new thought of the prevention and controlling towards Aspergillus flavus hazards.