Research Of Pectobacterium Phylogenetic Analysis And Its Host Perference With Carbapenem Synthetic Regulation

Pectobacterium spp.are the main pathogen(1988 ago were Erwinia spp.)caused bacterial soft rot and blackleg.The classification methods of Pectobacterium are largely different.The twelve isolates(our lab)collected from Jiangsu,Hubei,and Yunnan were identified as Pectobacterium using 16S rRNA,housekeeping genes(recA,mdh,rpoH and fliA)as well as Biolog.However,the species they belong were unclear.With the development of genome sequence,comparative genomic and one-to-one orthology were used to provide a direction for microbial classification.We analysized 12 Pectobacterium draft genomes.To further clarify the systematic taxonomy of 12 Pectobacterium and P.aroidearum,comparative genomics were constructed of the orthologous phylogenetic tree at genomal level,assisted with Average Nucleotide Identity(ANI)and In silico DNA-DNA hybridization(isDDH).Studies had shown that the phylogenetic tree based on 766 single-copy orthologs among 46 Pectobacterium spp.and Dickeya spp.clearly classified Pectobacterium into nine major taxas:P.carotovorum subsp.brasiliense(Pcb),P.carotovorum subsp.actinidiae(Pea),P.carotovorum subsp.carotovorum(Pcc),P.carotovorum subsp.odoriferum(Pco),P.wasabiae,P.betavasculorum,P.atrosepticum,P.parmentieri and P.aroidearum.The isDDH and ANI results also confirmed the result of phylogenetic tree.Furthermore,PccSl,PaNJAU150,PaNJAU160,and PaNJAU2 and PC1 were determined as new specie P.aroidearum independently.This was the first time that the systemic taxonomy determined as P.aroidearum at a genome-wide level.This study also analyzed the features and relative position of 15 HAIs in PccSl.The functions of gene islands(GIs)were divided into five types:whole or partial phages,metabolic islands,secreted islands,resistant islands,pathogenicity islands.In order to explore the preference of Pectobacterium to monocotyledonous or dicotyledonous host.We counted the host source of the 9 taxa strains and found all P.aroidearum strains were isolated from monocotyledon and had preference to it.In order to further study the preference of P.aroidearum,12 strains of Pectobacterium(lab)were used to infect cabbage,potatoes and calla lily.The results showed strains separated from the dicotyledonous(expecially the six Pcb strains)had a weaker pathogenicity to the Calla lily.In order to expore the factors that influence the difference of pathogenicity,the utilization of carbon sources,the production of PCWDEs(including pectinase,cellulase and protease)were determined but there was no obvious difference,it was indicated that the reason why the isolates had preference to the host was limited by using the carbon source and the degrading enzyme activity.Therefore,we speculated that the preference of the strains isolated from a dicotyledonous host may be the exsit of certain genes or effectors,and it needed further study.Carbapenem(car)genes among different species were also analyzed.The distribution of car genes had a big diversity in Pectobacterium,but not existed in Dickeya.PccS1,PcbNJAU132,PcbNJAU21,PcbNJAU140 had carA-E genes,all produced Car;PccS1,PcbNJAU132,PcbNJAU21,PcbNJAU140 had carF-carH genes,all had Car resistance,indicated genotype was consisted with phenotype.Moreover,previous studies had demonstrated that ?carI can produce OHHL but ?carI(carR)couldn't produce OHHL signal molecules.But this study found the activity of Car was recovered of ?carI(carR)and?carI(carl)in Car assay,respectively.Which implied the excessive CarR may recruit OHHL that generated from carI homologous gene.Pathogenicity assay found Acarl and?carI(carR)lost pathogenicity,indicated carI gene was related to pathogenicity.