Establishment Of Transgenomics For Identifying Populus Euphratica Oliv. Gene Clusters By Constructing BIBAC Library

Populus euphratica Oliv, which has adapted to saline soil and dry climate, is one of theearly appeared species in Salicacae. As the only woody plant to form a forest in saline-alkaliand desert are as in the north west of China, P.euphratica have diverged to adapt to severalstress conditions, such as salt-stress, drought, dry and heat air. Therefore, P. euphratica couldalso be used as a model for exploring stress tolerance genes or gene clusters. The BIBAClibrary with high-molecular-weight DNAs suitable for Agrobacterium-mediated planttransformation could be used for the estabishment of the transgenomics after transfomed intomodel plants like Araibdopsis thaliana. This platform will facilitate the functional genomics bydiscovering genes and gene clusters in the postgenome era.In this study, we constructed and characterized the BIBAC library of the P. euphraticagenome. Farther, the BIBAC clones were transformed into Arabidopsis via Agrobacterium byfloral dipping method, thus to establish a P. euphratica transgenomic platform. which could beused in characterization of P. euphratica genes or gene clusters. The results were outlined asthe following:1. P. euphratica BIBAC library was constructed, which included a total of55,296cloneswith the averge insert size of127kb. This BIBAC library represents a genome coverage ofabout13x equivalent of the P. euphratica genome. The quality of BIBAC clones was checkedand suggested that the P. euphratica BIBAC clones is stable before the use of planttransformation.2. We isolated cosmid DNAs from all the BIBAC cloned, about2,000of which weresuccessfully transformated into Agrobacterium tumefaciens strains GV3101. Finally1160ofthese strains were introduced into plants and the P. euphratica transgenomics had been partiallyestablished.3. Compared with wild-type Arabidopsisthaliana,49transgenic cloneshad shownphenotypic changes, of which20colnes of transgenic plants were repeatedly associated with the same phenotype: seven for growth; six for stem development and form; three for leaveform and color; two for silique size and shape; one for flower development and one for stresstreatment.4. Compared with the wild-type, of total143BIBAC clones screened with salt-stresstreatment, and002A1F06proved to be more salt tolerant than wild type plants. Then the127,284bp of002A1F06clone were sequenced and analyzed, which harbors105genes.5. Eight genes were found in these105genes to be involved in stress resistance. Such aspyrroline-5-carboxylate gene, ABC transporter ATP-binding protein gene(three genes),BolA-like protein gene, osmotically inducible protein C gene, iron transport receptor proteingene, short-chain dehydrogenase gene and membrane protein gene. These results indicatedthat002A1F06contains salt tolerance-related gene(s) or gene clusters, which might becontributed to the salt tolerance.These results suggeste that applying BIBAC library to establish the transgenomics isuseful to study the functional genomics of woody plants and discover the novel phenotypesgene(s) or gene clusters, for instance, stress-tolerance cluster genes.