文摘
Genetically modified cotton lines have been developed that are tolerantto glyphosate, the activeingredient in the herbicide Roundup. The new lines were generatedby Agrobacterium tumfaciens-mediated transfer of a gene encoding 5-enolpyruvylshikimate-3-phosphatesynthase isolated fromAgrobacterium sp. CP4 (CP4 EPSPS). Lines were screenedvia greenhouse spray tests and fieldevaluations to identify agronomically acceptable lines with acommercial level of tolerance toglyphosate. Two lines were characterized. Lines 1445 and 1698were transformed with differentvectors that encode for the CP4 EPSPS and the neomycinphosphotransferase II (NPTII) markerprotein. Both lines contain a single DNA insertion that segregatesin a typical Mendelian fashion.Line 1445 contains a single copy of the CP4 EPSPS gene, whereasthe line 1698 contains two copiesof the CP4 EPSPS gene at a single insertion site. The stability ofeach DNA insertion wasdemonstrated by Southern analysis across the R3 andR5 generations. The expression levels oftheCP4 EPSPS and NPTII were quantitated by ELISA in leaf and seed samplescollected in 1993 and1994 field trials. The use of glyphosate-tolerant cotton willenable the grower to take advantage ofadditional weed management alternatives.Keywords: Cotton; genetically modified; herbicide tolerant;Roundup