Functional Analysis Of The Transcription Factor Ss-Fkh1 In Sclerotinia Sclerotiorum(Lib.) De Bary

Sclerotinia sclerotiorum is a necrotrophic plant pathogen with worldwide distribution. And the pathogen can induce a large range loss in agriculture. Sclerotia of S.sclerotiorum are pigmented multihyphal structures that play a central role in the life and infection cycles of this pathogen. It can keep active through adverse environment. Being the key process from asexual to sexual makes it very important.The family of Forkhead-box have a structure of winged helix in the combination section with DNA. And the family of Forkhead-box plays a very important function in regulating mycelial growth、cell division、pathogenicity and so on.Ss-Fkh1 is one of four Forkhead-box containing transcription factors. To determine the function of Ss-Fkh1 in Sclerotinia sclerotiorum, this gene was cloned and RNA interference(RNAi)-based gene silencing was employed to alter the expression of Ss-Fkh1 in S. sclerotiorum. The vectors of p Silent、p Silent-Dual were used in the study. Silenced mutants were obtained using genetic transformation of the RNAi constructs p S1-Ss Fkh1 and p SD-Ss Fkh1. While, q RT-PCR was used to evaluate the expression levels of Ss-Fkh1 in silenced strains. RNA silencing mutants in which Ss-Fkh1 RNA levels were decreased significantly exhibited slow growth phenotype. Pathognicity on plants was significantly impaired in the Ss-Fkh1 mutants.Additionally, the expression level of genes related to melanin biosynthesis weresignificantly decreased and there was no sclerotia formation in silenced strains compared with wild type. As we all know,the biosynthesis of melanin is extremely important in forming sclerotia, there will no sclerotia presence when without melanin. So the pathogencity of S.sclerotiorum will greatly reduces. Resistance testing demonstrated that the gene of Ss-Fkh1 plays a function in it to a certain extent.All the results suggested that Ss-Fkh1 is involved in S.sclerotiorum hyphal growth, virulence, sclerotia formation and resistance related with adverse environment. Thus the research will make a foundation in prevention and cure the plant pathogen.