Construction And Qualification Of A BAC Library For YuGu 1 Of Foxtail Millet

Foxtail millet(Setaria italica(L.) Beauv.) was one of the most ancient cereal crops in the world.As a staple food,foxtail millet has made great contribution to society development especially in China.Foxtail millet was characterized with drought tolerance,salt tolerance,and was relatively balanced with necessary nutrition for human consummation and other special traits.Many amino acid which is necessary for human body is discovered content high in foxtail millet.Especially,the content of the insatuated facid aicd,which is an important factor effecting the development of the human's IQ,is very high in foxtail millet.Given the begining of the research about the genome of foxtail millet is relatively late compared with other crops',and its biotechnology genetic database was almost vacant,it is urgent to buid a"biotech-platform" in order to identify these important traits related genes.In order to get this goal,map based cloning is a major choice.Map based cloning includes 5 major factors, namely,the construction of the genetic map,the construction of the physical map,the construction of the high-throughput final map,the chorosome walking,and the identification of the gene.The most important step,namely,the chorosome walking required large numbers of the fragments of the genomic DNA.Genomic library was thus considered to be the core of the "platform".Construction of BAC library consists four parts:megabase DNA preparation,megbase DNA partial digestion and size selection,DNA transport and library assembly.A system characterized with high transport efficiency and low empty clone BAC library was established in this research.Beacuse the construction of BAC library is a time consuming and money-costting work,every step must be operated carefully.The key step of the process is the preparation of the HMW DNA which directly effects the follow steps.Finally,ligating the size-selected DNA fragments to the peBloBAC11 vector was used to construct a foxtail millet library of Yugu 1,which is a very popular cultivar.The library consists 36096 clones with 98%recombinants and 2%empty clones.The average length of the inserted fragments was 60-70kb and cover about 4-5 times of the foxtaii millet genome. This is the first BAC library of foxtail millet constructed in the world,and integrating with the oncoming foxtail millet genome sequence;it will for sure accelerate functional genomic study of this ancient crop,and will also make it easy for cereal comparative genomic study using foxtail millet.