Gcthionin is a novel plant defensin from Gymanadenia conopsea,a traditional Chinese herb.In the present paper,the recombinant plasmid pET-32(a)-Gcthionin was constructed,where the acid cleavage site –Asn-Pro-was introduced.Following the affinity chromatograph,the precipitated fusion protein was acid-cleavaged by using 50%formic acid[1].Tricine-SDS-PAGE showed that the target protein Gcthionin was successfully released with the apparent molecular mass of~21.8 kD.Protein purity was examined by analysis-grade HPLC analysis[2].Antifungal experimental datas indicate that Gcthionin exhibits inhibition activity against the hyphae growth and spore germination of agronomically important Fusarium.Graminearum[3].