Effect And Mechanism Of Host Banana On Fusarium Oxysporum Race 4 Based On Transcriptomic And Small RNA Analysis

Fusarium oxysporum f.sp.cubense race 4(Foc4)is a plant pathogenic fungi,which seriously threatens the development of banana industry.It may cause a large-area infection or even doom of banana plantations.In this study,the genome of Foc4 was resequenced and assembled to explore the interaction and mechanism between host bananas and Foc4,it was used as the reference genome.Then,the original Foc4 strain,the Foc4 strain derived from Nan Tian bananas and Brazil bananas were selected to do the experiments.The transcriptome,small RNA and degradome sequencing were used to detect the changes after Foc4 infection under different host stresses.With the analysis of changes on transcriptome and small RNA,the effect of hosts on Foc4 and its molecular mechanism were explored from different perspectives.The results are as follows:(1)In this study,the reassembled genome of the original Foc4 strain was 48129634 bp.There were 14207 annotated genes,including 1221 secretory proteins,536 virulence factors,2172 pathogenic genes(491 new pathogenic genes were identified),and 66 carbohydrate enzymes belonging to secretory proteins.Besides,the 66 enzymes could participate in the destruction of plant defense.The results were helpful for the analysis of pathogenicity and virulence of Foc4.(2)The mycelia of Foc4 were isolated from the roots of infected Nan Tian and Brazil bananas.They were cultured and enriched in vitro,so as the control group,to get NFoc4,BFoc4 and Foc4 samples,each group had 3 parallels.The results of transcriptome sequencing showed that Foc4 could respond to the defense of bananas through carbohydrate metabolism and lipid metabolism with difference in two hosts.The growth and development of fungi in the Nan Tian bananas were inhibited and their virulence were affected.(3)In this study,297 small RNAs from fungi were identified.NFoc4 from the Nan Tian bananas could promote protein renewal and the transport of nutrients in cells through ubiquitin proteasome system,endocytosis and vesicular transport pathway.They could promote the growth and toxicity of NFoc4,which revealed the response of fungi to stronger resistance of plants.(4)In this study,44 small RNAs from banana plants were identified.Mitophagy,phosphatidylinositol signaling system and valine,leucine and isoleucine biosynthesis were induced to decrease in NFoc4,thus the growth of fungi and its virulence were inhibited and regulated,which revealed the control and influence of Nan Tian bananas on NFoc4.The results showed that the interaction between bananas and Foc4 was a dynamic process between hosts and pathogens.It was revealed that banana plants could influence Foc4 through lots of ways,including inducing and regulating the transcriptome of Foc4 by small RNAs,while Foc4 would take a series of measures to deal with the plant defense,including the regulation of transcription through its own small RNAs to maintain the development and resist plant resistance.The results provided a theoretical basis for further study on the interaction mechanism between plants and pathogens,the development of new banana varieties and the biological control methods against Foc4.