Abstract:In this report,5 261 transconjugants of Dickeya zeaewere obtained by a mini-Tn5 transposon. PCR determination revealed that 267 mutants were inserted by Tn5. Pathogenicity assay on potato indicated that they all lost or reduced the ability to cause soft rot on potato. Furthermore,the assays for pathogenicity or virulence on rice and hypersensitive reaction(HR) on tobacco showed that 71 mutants had no virulence on rice, of which 59 mutants had no HR on tobacco. In addition, 68 mutants reduced virulence in rice,The rest of mutants have no obvious difference with EC1. Moreover, 146 of 267 Tn5 mutants had no HR on tobacco, of which 90 had no or reduced the virulence on rice. The above results indicated that the mutants were produced by inserting Tn5 transposon into different genes in D.zeae chromosome. The screened mutants from our Tn5-inserted mutant library provide the basis for the further understanding of molecular mechanisms of D.zeae pathogenicity in rice.