Identification Of Horizontal Gene Transfer In Mulberry

Horizontal gene transfer is commonly known as lateral gene transfer,somehow an organism gets genetic information from other organisms but not through the mode of reproduction,this natural spontaneous transgenic event is an universal phenomenon which is a significant way for acquiring genetic information,and it plays an important role in the entire life system.Horizontal gene transfer happens frequently in prokaryotes, it is a major source of genomic variation. Horizontal gene transfer is closely related to the wide spread of drug-resistant and brings about the pathogenicity to prokaryotes,and to a large exent,the evolution of prokaryotes also attributes to horizontal gene transfer.However, horizontal gene transfer also happens in eukaryotes,but the related researches are less.Because of the differentiation of somatic cells and germ cells,the foreign genetic information could be delivered to the future generation only if these information were integrated into the germ cells.At the same time, to avoid the cantamination of foreign genes,the genetic materials of eukaryotes are wrapped by the nuclear membrane,therefore,the possibility of horizontal gene transfer is relatively lower than that in prokaryotes.The identification of horizontal gene transfer in eukaryoes would provide a better perspective to explore the biological function of exogenous genetic variation,it is very important for understanding the evolution of the eukaryotes.Mulberry(Morus L.) is a perennial dicotyledonous woody plant,which spreads widely in various areas.The utilization of silkworm-mulberry interaction in China started from at least5000years ago.Mulberry is the food crop for the oligophagous economic domesticated silkworm(Bombyx mori),and it is the important material basis of the sericultural industry. With the features of resisting waterlogging and drought,having a atrong rooting force,mulberry can grow quickly on the barren soil,so mulberry possesses a valuable ecological function for protecting the environment. Studies about the horizontal gene transfer in mulberry can give us a better understanding about the genetic variation comes from horizontal gene transfer,which promotes the innovation of biological function in the recepients,and what’s more,it would help us to find out new genes through horizontal gene transferring,which would be the candidates for researching the functional genomics of the mulberry.Bioinformatic is effective for measuring the horizontal gene transfer,with the progressive technology of genomic sequencing,we get more and more genomic data of various species,which makes it possible for exploring horizontal gene transfer events.In this study,we predicted the horizontal transferred genes between M.notabilis and bacteria by the means of comparative genomics,as well,we analysised these predicted genes via PCR and sequencing technology.The main centents and results are as follows:1. Selecting the horizontal transferred genes from M.notabilisOn the basis of2684bacterial genomes and176sequence data from other spicies,we probed the horizontal gene transfer in M.notabilis by using the integrated methods of sequence similarity searching, typically with BLAST and homology sequence distrubution,and got314candidate genens.2.Phylogenetic analysis of these candidate genesThe phylogenetic analysis of these314candidate genes,finally we got4horizontal transferred genes. Three of them,Morus000087,Morus000171and Morus000209were found to be the phytopathogenic gene of γ-proteobacteria, while Morus000579was a plant symbiont gene from α-proteobacteria. These horizontal transferred genes involved in cell proliferation, metabolism and other physiological functions, suggesting that they could enhance the ability of mulberry for adaptting to the environment,and content of these exogenous nucleotide sequences also showed adaptive changes to M.notabilis genome.3.PCR cloning and sequencing of these genesWe identified that there was the Morus000579in M.notabilis genome by using the PCR and sequencing technoloty.The sequencing result showed that this612bp fragment amplificated from Morus000579were in consistent with the genomic database of M.notabilis,and there is no intron in the Morus000579.