| Fusarium wilt of banana caused by Fusarium oxysporum f.sp.cubense(Foc)is one of the most destructive fungal diseases.It substantially reduces the production and productivity of banana(Musa spp.).Brazil banana(Carvendish musa spp.AAA)is susceptible to Foc4,while a new cultivars named as Nantian banana has strong resistance to Foc4.But the banana-Foc4 interaction mechanism remains poorly defined.Thus,dual RNA-sequencing was utilized to detect both the pathogen and host transcripts before and after Foc4 inoculation.In this study,to determine the resistance mechanism in Nantian banana(N)compared to the control group Brazil banana(B),total RNA of root samples obtained before and 8 days after Foc4 inoculation was extracted and subjected to RNA sequencing(N0,B0,N8 and B8).Meanwhile,transcriptional profiling of pathogenic Foc4 in roots 8 d after Foc4 inoculation was analyzed(Fn8 and Fb8).In raw data,the average base number for all samples was 10991807301 bp,and the average clean base number was 10293699555 bp(more than 10 G),and the retention ratio of all samples was higher than 92.78%.The mapped rate of the transcriptional profiling to banana reference genome was 65.01%-75.33%,while the average mapped base of the pathogenic fungal transcriptional profiling in B and N banana cultivar compared Foc4 reference genome was to 13221300 bp and 23125800 bp,respectively.When the differential expression genes were identified and analyzed,they enriched in several metabolic pathways.For example,there are 6 pathway involving 15 differential expressed genes in the comparison of N8/B8 group,including cutin/suberine and wax biosynthesis,glycolysis/gluconeogenesis,mineral absorption,etc.GO annotation of the differentially expressed genes in the N8/B8 group comparison indicated that significant increase of biological process,including the biological adhesion,reproduction,antioxidant activity,enzyme regulator activity,structure molecular activity and transporter activity.And the biological processes that have been significantly reduced include developmental process,reproductive process,signaling,immune system process,negative regulation of biological process,etc.Additionly,the peroxidase genes in N8/N0 up-regulated significantly.Peroxidase could promote the lignin biosynthesis and the lignin could strengthen the plant cell wall to prevent the fungal invasion.Genes of pathogenesis-related proteins,chitinase and transcription factors were significantly up-regulated in B8/B0 with few change in N8/N0.On the other hand,totally 711 genes were significantly up-regulated or down-regulated in Fn8/Fb8.They mainly enriched in regulation of actin cytoskeleton,phagosome and endocytosis pathway.There are 4 endopolygalacturonase genes significantly up-regulated,which might target at degrading the cell walls of plants.These results indicated that since Foc4 faced more resistance in Nantian than Brazil during inoculation,it might have to recruit more powerful strategies to attack host.Dual RNA-sequencing unveils different host-pathogen interactions in the resistant and susceptible banana cultivars during Fusarium oxysporum race 4 challenge.Nantian employed cell wall strengthening and stomatal closure to prevent Foc4 infection while Brazil focused on activating internal immune system to prevent the invaded Foc4 to colonize.The Brazil banana might also inhibit the parasitics of Foc4 by secreting hydrolytic enzymes such as chitinase.In response to the stronger resistance in Nantian,Foc4 might attempt to increase its adhesion ability and secrete more hydrolases to destroy the host cell wall,as well as synthesize toxin substances.In summary,results of this study can provide promising clues for the further study of banana-Foc4 interaction mechanism,and might promote the cultivation of new banana varieties with disease resistance or provide new strategies to prevent banana wilt in the future. |
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