Primary Function Research On Qip Gene In Fusarium Oxysporum

RNA silencing mechanisms exist in many eukaryotes to reguLate avariety of biological processes, such as development, antiviral defence,and the maintenance of genomic stability. The known molecuLarcomponents are related to Dicers, Argonautes, and RNA-dependent RNApolymerases，Qip(QDE2-acting protein). Cabbage Fusarium wilt is one ofthe important fungal vascuLar disease which can make severelydamage of cabbage production worldwide. Fusarium oxysporum f.sp.conglutinans is the causal agent of this disease. In our study, the Qipgene in Fusarium oxysporum f. sp.conglutinans was disrupted usinghomologous recombination technology. We have study the function ofQip gene in Fusarium oxysporum. The content of research is as follows:1、Based on genome sequencing and analysis of12differentspecialized type of Fusarium oxysporum. We downloaded all annotatedQip protein sequences of F. oxysporum from NCBI. We used the Qip(QDE-2) protein of N. crassa (id: ABQ45366) as the query to searchagainst the annotated proteins of F. oxysporum. Interestingly, each ofthe12F. oxysporum strains had only one protein with a conservedDEDDh domain near the N-terminus (aa26–122), which indicates theybelong to the3’-5’ exonuclease domain family. We further analysed thesequence features of these12putative F. oxysporum Qip proteins usinga muLtiple sequence alignment. The amino acid sequences of F. oxysporum Qip protein were conserved, with all12being495aminoacids in length. Sequence diversity was detected in only15loci,suggesting that the functions of these proteins are also conserved.2、we successfuLly amplified the Qip gene of12different specializedtype of Fusarium oxysporum. The resuLts of RT-PCR showed that Qipgene in Fusarium oxysporum f. sp.conglutinans is expressed. The Qipgene in Fusarium oxysporum was disrupted using homologousrecombination technology. PCR confirmed the mutant was generated byhomologous recombination, and Southern showed the genome of theΔQip mutant contained only one copy of the hygromycin resistant gene.3、The deletion of the Qip gene resuLted in a decrease in colonygrowth rates but increased the number of branches. Additionally, theΔQip mutant had a reduced pathogenicity in cabbage. Our resuLtsshows Qip gene in Fusarium oxysporum is required for normal hyphaemorphology and viruLence. The mutant will be useful for elucidating therelationship between the RNA silencing mechanism and hyphal growthand development in F. oxysporum.