Infection State Of Pantoea Agglomeras In The Rice Water Weevil Lissorhoptrus Oryzophiuls Kuschel

Pantoea agglomerans is an important bacterial symbiont of insects.Despite its frequent discovery in various insect,little is known of its strain diversity,quantitative dynamics,and colonization site.The rice water weevil,Lissorhoptrus oryzophilus Kuschel,is a serious invasive pest in our country,and can cause serious damage to the rice production.Our previous work showed that L.oryzophilus" gut is colonized by several bacteria,of which P.agglomerans is one of major species.In this study,based on the cloning and sequencing of a bacterial 16S rRNA gene,we identified P.agglomerans strains diversity;the relative density in different tissues and development stages was detected with quantitative PCRs,colonization site in the gut and genetic transformation of P.agglomerans were operated.The results are as follows:The P.agglo,merans strains identified in four L.oryzophilus populations are extremely similar,and within each population,all the cloned P.agglomerans sequences were the same.In female adults,gut was the dominant tissue harboring P.agglomerans.This bacterium was also present in the ovary,but its density was very low there.The bacterium was maintained at a low density across all immature stages(from egg to pupa);however,the density increased substantially as adults emerged.Its density was low in the overwintering stage,but increased stepwise after the overwintered adults were allowed to feed on host plants,i.e.,when they developed from early to actively reproducing stages.The infection density returned to a low level in the adults at a late reproductive stage.These results indicate that P.agglomerans might have served as a response to the metabolic demand in feeding/reproducing females.The applied of fluorescence in situ hybridization,clarified that P.agglomerans mainly colonized the hindgut of L.oryzophilus.We transformed this bacterium with a DsRed-labeled plasmid and incestigated its fate in the host gut.Our results showed that this bacterium could be successfully transformed,while couldn't be colonized in the gut,the influence of host on symbiont might be the reason.In conclusion,we have provided a detailed profile of the symbiotic bacterium P.agglomerans in L.oryzophilus,including strain diversity,density in different tissues and developmental stages of the host,and colonization site.These results enrich our knowledge on the relationship between P.agglomerans and weevils,and provide the important basic theory for investigating the interaction mechanism between P.agglomerans and L.oryzophilus and biological control using this bacterium in the future.