Novel Species(Subspecies)Description And Entry Interceptions Analysis Of Plant-derived Enterobacteriaceae

Enterobacteriaceae are widespread in natural which could be distributed in the air,water,soil,human,animal and plant.They are conditional pathogens causing diseases such as pneumonia,sepsis,and bacteremia on human.They can infect and even kill insects.Also they can infect the plant,cause poplar canker,pear fire blight,elm wet heart and so on.In addition,Enterobacteriaceae also could be used as biological pesticide,nitrogen-fixing microorganisms and so on.They play a positive role in plant metabolism,plant growth,and pest controlling.Therefore,the research on Enterobacteriaceae is of great significance.Bacteria such as Dickeya chrysanthemi and Erwinia amylovora can infect plants such as iris,begonia and pear trees,causing severe economic losses,some of which are imported from abroad.To analyze bacteria intercepted in China entry plant quarantine in recent years,and to make sure the importance and the severity of bacteria invading China is facing now.This paper will provide a reference to the work of forestry plant quarantine.We analyzed the bacteria intercepted by China Entry Plant Quarantine during 2010-2015,according to the types of quarantine services,origins of sample products,and categories of quarantine bacteria.During 2010 to 2015,China had intercepted 139 species of bacteria and up to 7736 times in entry plant and plant production which were from 70 countries or regions;the main hosts for these bacteria intercepted were fruits and seeds;the bacteria interception included 16 species(10 species of which could infect flowers and forest.)and 521 times for quarantine bacteria,23 species and 835 times for pathogenic bacteria of flowers and forest,32 species and 2016 times for Enterobacteriaceae bacteria,and no Enterobacter cancerogenus,Erwinia amylovora and Erwinia pyrifoliae which are serious in Enterobacteriaceae found.During 2010 to 2015,both the species and the times intercepted had been on the increase.This made entry plant quarantine had become more serious and faced greater invading risks.This research chose plant-derived Enterobacteriaceae bacteria as the object of study.Five genes(16S rRNA,gyrB,rpoB,infB,atpD)were chose and maximum likelihood,neighbor joining and minimum evolution methods were used to analyze the Enterobacteriaceae phylogenetic relationships.The final result showed a low confidence level commonly in branch nodes of ML tree,NJ tree and ME tree which were created based on 16 S rRNA.For example,most branch nodes of ML tree had a confidence level lower than 50%.Some species and genera performed unstable positions in phylogenetic trees of 16 S rRNA gene created by different methods.ML tree,NJ tree,and ME tree based on house-keeping gene got high rate of support.It indicated this evolutionary tree had well display for Enterobacteriaceae classification.The structure of the tree topology of ML tree,NJ tree,and ME tree has high consistency,and every genus in evolution tree had stable position.This paper identified and described three new species of genus Brenneria with morphology methods,physiological and biochemical methods,and molecular biological methods.These three new species were new subspecies of B.populi,new subspecies of B.salicis and new subspecies of B.goodwinii.