Bleeding canker,a devastating disease of pear trees(Pyrus pyrifolia L.),was first reported in the 1970 s in Jiangsu,China and more recently in other provinces in China.Trees infected with bleeding canker pathogen,Dick...Bleeding canker,a devastating disease of pear trees(Pyrus pyrifolia L.),was first reported in the 1970 s in Jiangsu,China and more recently in other provinces in China.Trees infected with bleeding canker pathogen,Dickeya fangzhongdai,develop cankers on the trunks and branches,and a rust-colored mixture of bacterial ooze and tree sap could be seen all over the trunks and branches.In this study,we provided detail descriptions of the symptoms and epidemiology of bleeding canker disease.Based on pathogenic and phenotypic characterizations,we identified the causal agent of bleeding canker of pear as D.fangzhongdai.Dickeya fangzhongdai strains isolated from pear were also pathogenic on Solanum tuberosum,Brassica pekinensis,Lycopersicon esculentum,and Phalaenopsis aphrodite based on artificial inoculation,and the pathogen were more virulent on potato than that of D.solani strain.This study provides new information about this disease and bleeding canker disease of pear.展开更多
Dickeya fangzhongdai, the causal agent of bleeding canker of pear, is a new member of the Dickeya genus and the only one that infects woody plants. Recent studies have reclassified several Dickeya isolates as D. fangz...Dickeya fangzhongdai, the causal agent of bleeding canker of pear, is a new member of the Dickeya genus and the only one that infects woody plants. Recent studies have reclassified several Dickeya isolates as D. fangzhongdai, which were isolated from various environments, including water, Phalaenopsis sp. and Aglaonema sp. To provide genomic characterization of D. fangzhongdai isolates from pear, the genomes of D. fangzhongdai strain JS5(=China General Microbiological Culture Collection Center, CGMCC 1.15464 ~T=DSM 101947 ~T), along with two other isolates, LN1 and QZH3, were sequenced and compared to those of other Dickeya spp. Homology greater than 99% was observed among three D. fangzhongdai strains. Plasmid, type IV secretion system(T4 SS) and type IV pili(TFPs) were found in genomes of D. fangzhongdai isolates. Comparative analysis of the type Ⅲ secretion systems(T3 SS), type Ⅲ secretion effectors(T3 SE), plant cell wall degradation enzymes(PCWDE) and membrane transport proteins of Dickeya spp. showed some differences which might reflect the variations of virulence, phylogenetic and phenotypic characteristics of Dickeya spp. In addition, deletion mutant of TFP in D. fangzhongdai JS5 showed no twitching motility and reduced virulence and biofilm formation. The fingdings of the distinctive plasmid, T4 SS and TFPs, as well as the differences of T3 SE, PCWDE and membrane transport proteins make D. fangzhongdai isolates unique. These results also suggested that acquisition of virulence genes by horizontal gene transfer might play some role in the genetic variation of D. fangzhongdai.展开更多
基金supported by the 111 International Cooperation Grant 2.0(BP0719029)to Nanjing Agricultural University,China,from the Chinese government and Canadian Interdepartmental funding of Genomics Research and Development Initiatives(GRDI)。
文摘Bleeding canker,a devastating disease of pear trees(Pyrus pyrifolia L.),was first reported in the 1970 s in Jiangsu,China and more recently in other provinces in China.Trees infected with bleeding canker pathogen,Dickeya fangzhongdai,develop cankers on the trunks and branches,and a rust-colored mixture of bacterial ooze and tree sap could be seen all over the trunks and branches.In this study,we provided detail descriptions of the symptoms and epidemiology of bleeding canker disease.Based on pathogenic and phenotypic characterizations,we identified the causal agent of bleeding canker of pear as D.fangzhongdai.Dickeya fangzhongdai strains isolated from pear were also pathogenic on Solanum tuberosum,Brassica pekinensis,Lycopersicon esculentum,and Phalaenopsis aphrodite based on artificial inoculation,and the pathogen were more virulent on potato than that of D.solani strain.This study provides new information about this disease and bleeding canker disease of pear.
基金supported by the 111 International Cooperation Grant 2.0(BP0719029)to Nanjing Agricultural University,China,from the Chinese government and Canadian Interdepartmental funding of Genomics Research and Development Initiatives(GRDI)。
文摘Dickeya fangzhongdai, the causal agent of bleeding canker of pear, is a new member of the Dickeya genus and the only one that infects woody plants. Recent studies have reclassified several Dickeya isolates as D. fangzhongdai, which were isolated from various environments, including water, Phalaenopsis sp. and Aglaonema sp. To provide genomic characterization of D. fangzhongdai isolates from pear, the genomes of D. fangzhongdai strain JS5(=China General Microbiological Culture Collection Center, CGMCC 1.15464 ~T=DSM 101947 ~T), along with two other isolates, LN1 and QZH3, were sequenced and compared to those of other Dickeya spp. Homology greater than 99% was observed among three D. fangzhongdai strains. Plasmid, type IV secretion system(T4 SS) and type IV pili(TFPs) were found in genomes of D. fangzhongdai isolates. Comparative analysis of the type Ⅲ secretion systems(T3 SS), type Ⅲ secretion effectors(T3 SE), plant cell wall degradation enzymes(PCWDE) and membrane transport proteins of Dickeya spp. showed some differences which might reflect the variations of virulence, phylogenetic and phenotypic characteristics of Dickeya spp. In addition, deletion mutant of TFP in D. fangzhongdai JS5 showed no twitching motility and reduced virulence and biofilm formation. The fingdings of the distinctive plasmid, T4 SS and TFPs, as well as the differences of T3 SE, PCWDE and membrane transport proteins make D. fangzhongdai isolates unique. These results also suggested that acquisition of virulence genes by horizontal gene transfer might play some role in the genetic variation of D. fangzhongdai.
