Pathogen identification of Ageratum conyzoides bacterial wilt disease and its biological characteristics

She Xiaoman;He Zifu;Luo Fangfang;Institute of Plant Protection,Guangdong Academy of Agricultural Sciences,Guangdong Provincial Key Laboratory of High Technology for Plant Protection;

Ageratum conyzoides bacterial wilt;;identification of pathogen;;Ralstonia solanacearum

Ageratum conyzoides bacterial wilt is a new disease in China. To investigate the etiology of the disease,the colony morphology,16S rDNA sequence,carbohydrate utilization,pathogenicity and phylotype of the bacterium isolated from the diseased A. conyzoides plants were studied. On the selective medium containing 1% 2,3,5-triphenyl tetrazolium chloride( TZC),the morphology of the bacteria exhibited irregular round,upheaval,fluidal and pink colonies with white margin. The 16S rDNA fragments of the 10 strains were amplified by PCR using the universal bacterial 16S rDNA primer set 27f /1541R. The nearly full-length 16S rDNA sequences of the 10 strains were determined to be 1 421 bp,and shared100% sequence identity with the 16S rDNA of Ralstonia solanacearum isolate GMI1000. The results of carbohydrate utilization and pathogenicity tests showed that the 10 stains were able to oxidize lactose,maltose,cellobiose,mannitol,dulcitol,and sorbitol,and could strongly infect ginger,Rhizoma kaempferiae and tomato,but weakly infect pepper and eggplant. The result of phylotype multiple PCR indicated that the specific 280 bp and 144 bp fragments were amplified from all 10 strains,respectively. These results demonstrated that the pathogen of A. conyzoides bacterial wilt belonged to Race 4,Biovar Ⅲ and PhylotypeⅠ( Asiaticum division),of R. solanacearum.