the necessity of transgenic technology in sustainable production

it has been more than half a century that plant geneticists and breeders have been trying to assemble a combinationof genes in crop plants, in order to make them as suitable and productive as possible. plant transformation technology incrop plants was first undertakenin the 1980s based on the ability of foreign gene integration into host plant genome andregeneration of transformed plant cells into whole plants. soon after, transgenic plants were to be grown by farmers.statistics show that farmers have started to cultivate genetically modified plants (gmps) commercially since 1996.between 1996 and 2012, the total surface area of land cultivated with gm crops has increased from 2 million hectaresto more than 170 million hectares in 29 countries. to this extent, some concerns have been raised by ecologists andconsumer organizations in west european countries based on the possibilities of horizontal and vertical gene flow ofantibiotic or herbicide resistance from transgenic plants into human intestinal bacteria and some weeds via outcrossing,respectively. due to consumer and ecologist concerns, different approaches have been developed to eliminate marker(and/or reporter) genes from the nuclear or chloroplast genome after selection. some of these proposed methods are:1. replacing selectable markers with screenable ones.2. elimination of marker genes by co-transformartion followed by classic recombination and selection.3. excision of marker gene by some site-specific recombinases.4. separation of the transgene and selectable marker by transposable elements.5. avoiding gene pollution by chloroplasts genetic engineering followed by elimination of selectable marker.