Studies On Safety Assessment Of Transgenic Bt Poplar

Plant engineering developed rapidly during recent 20 years.Transgenictechnology has been effectively used for the improvement of plant cuntivars.A greatamount of transgenic plant have been released for commercial use in recentyears.Transgenic plant is different from the traditional one in that the formercontains foreign genes which leads to public concern.The environmental safety offoreign genes in transgenic plants has been disscussed in this paper.The safety oftransgenic plant commercialized in a large scale received much concern since it hasa close relationship with creatures and environment protection and human health.Thegoal of this paper is to provide a scientific Framework to assess potentialenvironment risks associated with transgenic woody biomass crops. Trees differentfrom most agricultural crops in that they persist in the landscape for long periodsof time.This different timeframe not only increase the probability that any one treecrop will be subjected to a much wider range of stress conditions,but also that anystress-induced side-effect of GM technology will be much harder to detect andaddress.Meanwhile,remote location and less intense management regimes mean limitedopportunities for monitoring ,control and enforcement of regulations while makingearly detection of unanticipated problems highly unlikely.The work in this paperincludes three aspects.The first is about the literature.The literature pertaining to environmenteffects of genetically engineered insect resistance crops is briefly reviewed andthe relevance of this information to transgenic woody biomass crops isdiscussed ,particularly in regard to how ecological and genetic factors influencerisk.The second is to detect the stability of foreign gene in Bt poplar,thetransmission of the transgene to the tree progenies and develop a protocol ofdetection Bt gene in tree sample by means of PCR technique.PCR is adopted to analyzethe expression of insectidal protein gene Bt in the transgenic poplar plants.Theresults show that the expression of the protein gene was stable at the seven yearof the plantation.Several flowers were collected from a male transgenic tree andpollinated in controlled conditions.Progeny seeds were germinated and grown invitro.Analyses revealed that segregation appreas to follow Mendal's rule as 67 outof 120 individual tested exhibit transgene expression in accordance with the awaited1:1 segregation.A stable expression of the Bt gene was detected in both the parentand F1 progenies.These physiological differences,maybe caused by gene transfer andtissues culture,could induce changes in secondary metabolism of Bt poplar and thenbring ecological effects to environment.This kind of effect should also be animportant aspects of ecological risk assessment of transgenic plants release intoenvironment.The application of PCR detection in safety assessment is discussed.The thrid level of this work is to reveal that there was no much insect and spidercommunity difference between transgenic and non-transgenic poplar trees of the smallplanted area while in large planted area obvious difference of that was observed.Through the comparison of insect and spider community structures between puretransgenic poplar stand and 1:1 mixed stand of transgenic and non-transgenic poplars,it is clear that Bt transgenic poplar can influence the insect community structure.In pure transgenic poplar stand, dominant species is poplar sawfly (Pristiphorabenjingensis Zhou et Zhang) while in mixed poplar stand is poplar prominent (Closteraanachoreta (Fabricus)). It demonstrates that transgenic poplar can suppress theLepidopteran species and at same time may favorable to other defoliators. To reducethe risky of being damaged by other non-lepidoptera defoliators resistant speciesto this kind of pest species should be used when B.t. gene is transferred. The damagerate of pure transgenic poplar stand and mixed transgenic poplar stand were 11.26%and18.48% respectively, the former was better but no significant difference. Thediversity and uniformity of pure transgenic poplar stand were higher than that ofMixed transgenic poplars stand which leads to higher stability. However the densityof lady beetles was 10 times higher in mixed transgenic poplar stand than puretransgenic poplar stand, averagely 0.21 per twig and 0.021per twig respectivelywhile the density of spiders in pure transgenic poplar stand was higher than thatin mixed transgenic poplar stand, averagely 0.125 per twig and 0.0625 per twigrespectively. Further study is needed in the effect of transgenic poplars to thenon-target insects and natural enemies.Because the subject arise only less than 30yaer and the data are not rich enough,the theory and technique of safety assessmentneed much improvement.This work applies technique of molecular biology and community ecology ,combinesthe phenomena in field and completes a comprehensive safety assessment of transgenicBt poplar.