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IMPRECISION & UNPREDICTABILITY OF S & T OF GENETIC ENGINEERING29. Matthews, D., Jones, H., Gans, P., Coates, S., & Smith, L. M. (2005) : Toxicsecondary metabolite production in genetically modified potatoes inresponse to stress. J Agric Food Chem 53 : 7766-76.Potatoes produce a number of toxic secondary metabolites, which are dividedinto two groups: the sesquiterpenes and the glycoalkaloids (PGAs): whereasPGAs are largely preformed and present in toxic quantities in both the foliage and“green” potatoes, it is well documented that the levels of PGAs and sesquiterpenesare effected by many biotic an abiotic stresses. The development of geneticallymodified potato varieties has made it prudent to ascertain whether there may bechanges in the amounts or types of these secondary metabolites either as adirect effect of the transgene or due to its interactions with environmental variables.Transgenic potato lines were exposed, along with nontransgenic lines, to a rangeof biotic and abiotic stresses and a range of environmental conditions in the fieldand store. Following stressing, a comparison was made of levels of potatoglycoalkaloid and sesquiterpene levels between the two groups. Significantdifferences were observed in the levels of both glycoalkaloid and sesquiterpenelevels between transgenic and control material and between infected andnoninfected material.30. Somers DA, Makarevitch I. (2004) : Transgene integration in plants: pokingor patching holes in promiscuous genomes? Curr Opin Biotechnol. 15 (2):126-31.Transgene integration in plants transformed by either Agrobacterium or directDNA delivery methods occurs through illegitimate recombination (IR). The precisemechanism(s) for IR-mediated transgene integration and the role of host doublestrandbreak repair enzymes remain unknown. A recent wealth of sequencedtransgene loci and investigations aimed at genetically dissecting transgeneintegration mechanism(s) have provided new insights into the process.http://www.ncbi.nlm.nih.gov/pubmed/1508105031. Wilson AK, Latham JR, Steinbrecher RA. (2004) : Genome Scrambling-Myth or reality? Transformation-induced mutations in transgenic cropplants. Brighton, UK: EcoNexus; 2004. Technical Report.Plant transformation is a genetic engineering tool for introducing transgenes intoplant genomes. It is now being used for the breeding of commercial crops. Acentral feature of transformation is insertion of the transgene into plantchromosomal DNA. Transgene insertion is infrequently, if ever, a precise event.Mutations found at transgene insertion sites include deletions andrearrangements of host chromosomal DNA and introduction of superfluous DNA.Insertion sites introduced using Agrobacterium tumefacienstend to have simpler(17)