Abstract
Phytopathogenic Fusarium species produced a trichothecene family of phytotoxins. Trichothecene-contaminated grains and commodities are frequently reported all over the world. We are studying the mode of action of trichothecenes in Fusarium-susceptible Arabidopsis plants. We reported an AtNFXL1 gene as type A trichothecene, T-2 toxin-inducible gene. The AtNFXL1 gene negatively regulates the T-2 toxin-inducible defense response via a SA biosynthesis. Furthermore, we identified a thionin2.3 as a component of an AtNFXL1 protein complex. Thionin proteins are generally known as antimicrobial proteins. In fact, the thionin2.3 protein expressed in E. coli effectively inhibited the hyphal growth of F. sporotrichioides in media. When leaves of Thi2.3-overexpressed Arabidopsis plants were inoculated with conidia of F. sporotrichioides,their hypal extension was significantly inhibited compared with wild type plants. In addition, disease symptoms were decreased in F. sporotrichioides-inoculated Thi2.3-ox flowers compared with wild type. Thus, the Arabidopsis Thi2.3 protein has an antifugal activity against F. sporotrichioides by inhibition of their hyphal growth.
