Marker Gene Controversy in Transgenic Plants

Malik, V. S.; Saroha, Monika

doi:10.1007/bf03263050

Cited by 14 publications

(14 citation statements)

References 94 publications

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“…For soybean, as with other plant species, there is a limited number of marker genes available for use in transformation protocols. Moreover, the perceived risks that have been associated with some selectable markers (Malik and Saroha, 1999) may delay public acceptance of genetically enhanced soybeans.…”

Section: Discussionmentioning

confidence: 99%

The use of the two T-DNA binary system to derive marker-free transgenic soybeans

Xing

Zhang

Sato

et al. 2000

In Vitro Cell.Dev.Biol.-Plant

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A binary vector, pPTN133, was assembled that harbored two separate T-DNAs. T-DNA one contained a bar cassette, while T-DNA two carried a GUS cassette. The plasmid was mobilized into the Agrobacterium tumefaciens strain EHA101. Mature soybean cotyledonary node explants were inoculated and regenerated on medium amended with glufosinate. Transgenic soybeans were grown to maturity in the greenhouse. Fifteen primary transformants (T 0 ) representing 10 independent events were characterized. Seven of the 10 independent T 0 events co-expressed GUS. Progeny analysis was conducted by sowing the T 1 seeds and monitoring the expression of the GUS gene after 21 d. Individual T 1 plants were subsequently scored for herbicide tolerance by leaf painting a unifoliate leaf with a 100 mg l 21 solution of glufosinate and scoring the leaf 5 d post application. Herbicide-sensitive and GUS-positive individuals were observed in four of the 10 independent events. Southern blot analysis confirmed the absence of the bar gene in the GUS positive/herbicide-sensitive individuals. These results demonstrate that simultaneous integration of two T-DNAs followed by their independent segregation in progeny is a viable means to obtain soybeans that lack a selectable marker.

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Section: Discussionmentioning

confidence: 99%

The use of the two T-DNA binary system to derive marker-free transgenic soybeans

Xing

Zhang

Sato

et al. 2000

In Vitro Cell.Dev.Biol.-Plant

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“…The presence of antibiotic resistance genes in genetically engineered crops has generated a number of environmental and consumer concerns for long time, despite of scientific evidences (Malik and Saroha 1999). Avoidance of a selection system is feasible in potato (de Vetten et al 2003) but requires high efficiencies of transformation and regeneration that are genotypedependant (Heeres et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Self-excision of the antibiotic resistance gene nptII using a heat inducible Cre-loxP system from transgenic potato

et al. 2006

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Resistance to antibiotics mediated by selectable marker genes remains a powerful selection tool for transgenic event production. However, regulatory agencies and consumer concerns favor these to be eliminated from food crops. Several excision systems exist but none have been optimized or shown to be functional for clonally propagated crops. The excision of the nptII gene conferring resistance to kanamycin has been achieved here using a gene construct based on a heat-inducible cre gene producing a recombinase that eliminates cre and nptII genes flanked by two loxP sites. First-generation regenerants with the Cre-loxP system were obtained by selection on kanamycin media. Following a heat treatment, second generation regenerants were screened for excision by PCR using nptII, cre, and T-DNA borders primers. Excision efficiency appeared to be at 4.7% depending on the heat treatment. The footprint of the excision was shown by sequencing between T-DNA borders to correspond to a perfect recombination event. Selectable marker-free sprouts were also obtained from tubers of transgenic events when submitted to similar heat treatment at 4% frequency. Spontaneous excision was not observed out of 196 regenerants from untreated transgenic explants. Biosafety concerns are minimized because the expression of cre gene driven by the hsp70 promoter of Drosophila melanogaster was remarkably low even under heat activation and no functional loxP site were found in published Solanum sequence database. A new plant transformation vector pCIP54/55 was developed including a multiple cloning site and the self-excision system which should be a useful tool not only for marker genes in potato but for any gene or sequence removal in any plant.

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“…This will give to the bacteria an antibiotic-resistant phenotype [142,143]. Because bacteria can exchange genetic information, this gene can be passed on to other bacteria present, and during an infection, this particular situation will make it difficult to eliminate from the human body.…”

Section: Horizontal Gene Transfer Involving Transgenic Foodmentioning

confidence: 99%