Molecular identification and genetic diversity in Konnyaku''''s soft rot bacteria
魔芋软腐病菌分子鉴定与遗传多样性

The soft rot bacteria Erwinia are an important pathogens of konnyaku and other ornamental plants.Thirty-three strains were isolated from soft-rotted konnyaku and other ornamental plants.According to the characteristics of pathogenicity and culture character on semi selective medium(crystal violet pectate,CVP),most of strains tested caused rotten symptom in tubers and stems of konnyaku,and characteristic deep cavities were formed on CVP.To amplify 16S-23S rDNA intergenic transcribed spacer(ITS) by PCR and electrophorese through agarose gel,most strains are clustered into two heterogeneous populations of Erwinia carotovora subsp.carotovora,E.c.c.and Erwinia chrysanthemi,E.ch..Besides,several other strains could not be identified into species by ITS-PCR.The characteristic band patterns of E.c.c. and E.ch.could be clearly distinguished by repetitive element-polymerase chain reaction(rep-PCR,BOX and J3 primers).And the fingerprinting of E.c.c.stains were also different from each other.Dendrogram was generated from the data of primer BOX by using UPGMA analysis because the primer BOX was higher resolution than other primers(such as prime J3) for identifying the same intraspecies strains.Strains of E.c.c.were divided into five groups on the 0.1 level of linkage distance.