Function Analysis Of Dicer,Argonaute And Rdrp Involved In Small RNAs Biogenesis In Fusarium Oxysporum

In eukaryotes, small RNAs play an important role in modifying chromatin, degradating mRNA, inhibiting mRNA translation, suppressing transposon translocation, resisting viruses and so on. Previous studies showed that the small RNAs generation mechanism involved a series of proteins, and the core components were Dicer, Argonaute and RNA dependent RNA polymerase (Rdrp). In this study, Fusarium oxysporum f.sp.conglutinans race1FOX-A8strain was used as the representative experimental materials for Fusarium oxysporum. The function of Dicer (Dcr), Argonaute(Ago) and Rdrp were reseached through comparing the growth, phenotype and pathogenicity between the wild type and Dicer, Argonaute, Rdrp gene deletion mutants (ΔDcr1, ΔDcr2, ΔDcrl/2, ΔAgol, ΔAgo2, ΔAgo1/2, ΔRdrp1, ΔRdrp2and ΔRdrp3). Our study will lay a theoretical basis for revealing the molecular genetic mechanisms of the small RNAs generation. The results are as follows:Dcr2is apparently involved in the mycelia growth. Compared with the wild type, the hyphae of ADcr2and ΔDcr1/2have more branches, the mycelial biomass of ΔDcrl1, ΔDcr2and ΔDcr1/2have serious decline, and the conidium biomass and numbers of ΔDcrl1、ΔDcr2and ΔDcr1/2are obviously increase, but the total biomass of ΔDcr1、ΔDcr2and ΔDcr1/2have few differences. The conidium morphology of ΔDcrl、 ΔDcr2and ADcr1/2have no change. These phenomenons showed that Dcr played important role in regulating the relation between mycelia growth, development and reproduction. The results of infecting kale experiments showed that Dcr had no obvious effect on the pathogenicity of Fusarium oxysporum.Agol is associated with conidial morphology development, compared with the conidium of wild type, the conidium morphology of ΔAgol is round shape and similar to the yeast cells, and the size is about one-half of wild type, and the conidium of ΔAgol can multiply as the reproduction of budding yeast. Ago2is related with mycelium growth, compared with the wild type, AAgo2have more branches. Ago1and Ago2inhibit the conidial reproduction and promote the hyphae growth in the earlier growth stages of Fusarium oxysporum. The results of infecting kale experiments showed that Ago had no obvious effect on the pathogenicity of Fusarium oxysporum.Rdrp2and Rdrp3is associated with conidium morphology development, compared with the conidium of wild type, the conidium morphology of ARdrp2and ARdrp3is oval shape and like the wolfberry, and the size is nearly one-tenth of the wild type, and the conidium of ΔRdrp2and ΔRdrp3can multiply as the reproduction of budding yeast, and also can reproduct a series of small wolfberry shape conidium from a large structure similar to the sporangium. Rdrp2and Rdrp3is also associated with hyphae development, the hyphae morphology of ARdrpl, ARdrp2and ARdrp3have malformation change, ΔRdrp2and ΔRdrp3have more branches. ARdrpl, ARdrp2and ARdrp3have a slow growing when the culture temperature is14℃or33℃. When the culture temperature is25℃, the conidium production of ΔRdrp1, ΔRdrp2and ΔRdrp3is successive more than that of wild type, the hypha production of ARdrpl, ΔRdrp2and ΔRdrp3is successive less than that of wild type, but the total biomass of ΔRdrp1, ΔRdrp2and ARdrp3have few differences with that of wild type. The pathogenicity of ΔRdrpl, ΔRdrp2and ARdrp3decreased, especially ARdrp2and ΔRdrp3, this showed that Rdrp is related to the pathogenicity of Fusarium oxysporum.In short, Dcr, Ago and Rdrp is related with the growth and development of Fusarium oxysporum in various degrees, even greater concern is that the conidial morphology of ΔAgo1,ΔRdrp2and ΔRdrp3obviously change, the mechanism of this change is unclear, and there is no similar reports, so the mechanism require further study.