The Role Of Small RNA In Resistant Banana Cultivar During Fusarium Oxysporum Race 4 Challenge

Fusarium wilt of banana caused by Fusarium oxysporum f.sp.cubense(Foc)is a soil-borne fungal epidemic,which can cause banana wilt,yellowing and even death.It has seriously threatened the development of the banana industry.Among them,Foc4 is the physiological race with the strongest infectivity and toxicity.In this experiment,small RNA sequencing and degradome sequencing were combined.The new resistant variety Nantian banana(N)and the susceptible Brazil banana(B)and pathogenic fungal Foc4 were taken as the research objects to study the regulation effect of banana small RNA from two aspects.On the one hand,the two banana roots before and after infection(N0,N8,B0 and B8)were used as experimental materials.4 small RNA sequencing libraries and one degradome library were constructed and verified by RT-qPCR experiments to study the banana miRNA endogenous effects;on the other hand,Foc4 myceliums isolated from the bulbs of Nantian banana and Brazil banana(NFoc4 and BFoc4)and the Foc4 mycelium(Foc4)cultured in laboratory were used as experimental materials.9 Small RNA sequencing libraries and three degradome libraries were constructed to study the transboundary transfer of banana small RNA and its possible role.Combining bioinformatics analysis and processing the obtained data,the main conclusions are as follows:Based on the analysis of 4 small RNA sequencing data of banana roots B0,B8,N0 and N8,152 known miRNAs,belonging to 28 miRNA families and 59 novel miRNAs were identified.The target genes of banana root miRNAs were identified by degradome sequencing,a total of 1113 miRNA-m RNA pairs were obtained.Differentially expressed miRNAs participate in plant hormone signal transduction and plant-pathogen interaction pathways through negative regulation of target genes,affecting banana-Foc4 interactions.It is speculated that miRNA-mediated regulation of target gene expression is one of the reasons why Nantian banana has higher resistance.Nine small RNA sequencing libraries were constructed using NFoc4,BFoc4 and Foc4.a total of 6 banana small RNAs transferred across the border to Foc4 were identified,including 2 miRNAs and 4 s RNAs.the target genes of banana small RNA in fungus Foc4 were identified by degradome sequencing,it was found that the mus-novel miR1 target gene encodes pyridoxamine 5’-phosphate oxidase and peroxisomal long-chain fatty acid import protein 2,Mus-s RNA4 target gene encoding SLG1 protein involved in the MAPK signaling pathway.These target genes may be related to the expression of Foc4 virulence factor.In addition,it was also found that the Mus-s RNA2 target gene encoding FBP1-fructose-1,6-bisphosphatase is involved in energy metabolism-related pathways,affecting fungal growth and development.These results of small RNA research will provide an important reference for the study of the mechanism of banana-Foc4 interaction,and provide a new idea for the control of Fusarium wilt.