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Glyphosate selection has been implemented into an Agrobacterium-mediated transformation system for soybean [Glycine max (L.) Merr.]. Cotyledonary explants were excised from 5-d-old seedlings and inoculated with an Agrobacterium strain carrying the CP4 gene, which confers tolerance to the herbicide Roundup, and the Β-glucuronidase (GUS) gene. Explants were selected on sublethal levels of glyphosate during shoot initiation and elongation. Glyphosate tolerant shoots were identifiable after 8 to 12 wk of selection. Coexpression of GUS occurred in approximately 80% of the primary transformants ([R.sub.0]). The [R.sub.0] plants were fully fertile, with no apparent phenotypic abnormalities. Progeny analysis from 81 independent transgenic soybean events derived from glyphosate selection demonstrated that the majority of the transformants transmitted the transgenes as a single functional locus., BROADENING the gene pool of soybean via plant gene transfer techniques has been accomplished for such traits as herbicide tolerance (Padgette et al., 1995), amino acid modification (Falco et al., [...]

Pollen elimination provides an effective containment method to reduce direct gene flow from transgenic trees to their wild relatives. Until now, only limited success has been achieved in controlling pollen production in trees. A pine (Pinus radiata) male cone-specific promoter, PrMC2, was used to drive modified barnase coding sequences (barnaseH102E, barnaseK27A, and barnaseE73G) in order to determine their effectiveness in pollen ablation. The expression cassette PrMC2-barnaseHlO2E was found to efficiently ablate pollen in tobacco (Nicotiana tabacum), pine, and Eucalyptus (spp.). Large-scale and multiple-year field tests demonstrated that complete prevention of pollen production was achieved in greater than 95% of independently transformed lines of pine and Eucalyptus (spp.) that contained the PrMC2-barnaseHlO2E expression cassette. A complete pollen control phenotype was achieved in transgenic lines and expressed stably over multiple years, multiple test locations, and when the PrMC2-barnaseHlO2E cassette was flanked by different genes. The PrMC2-barnaseHlO2E transgenic pine and Eucalyptus (spp.) trees grew similarly to control trees in all observed attributes except the pollenless phenotype. The ability to achieve the complete control of pollen production in field-grown trees is likely the result of a unique combination of three factors: the male cone/anther specificity of the PrMC2 promoter, the reduced RNase activity of barnaseH102E, and unique features associated with a polyploid tapetum. The field performance of the PrMC2-barnaseHlO2E in representative angiosperm and gymnosperm trees indicates that this gene can be used to mitigate pollen-mediated gene flow associated with large-scale deployment of transgenic trees. [ABSTRACT FROM AUTHOR]

Pollen elimination provides an effective containment method to reduce direct gene flow from transgenic trees to their wild relatives. Until now, only limited success has been achieved in controlling pollen production in trees. A pine (Pinus radiata) male cone-specific promoter, PrMC2, was used to drive modified barnase coding sequences (barnaseH102E, barnaseK27A, and barnaseE73G) in order to determine their effectiveness in pollen ablation. The expression cassette PrMC2-barnaseHlO2E was found to efficiently ablate pollen in tobacco (Nicotiana tabacum), pine, and Eucalyptus (spp.). Large-scale and multiple-year field tests demonstrated that complete prevention of pollen production was achieved in greater than 95% of independently transformed lines of pine and Eucalyptus (spp.) that contained the PrMC2-barnaseHlO2E expression cassette. A complete pollen control phenotype was achieved in transgenic lines and expressed stably over multiple years, multiple test locations, and when the PrMC2-barnaseHlO2E cassette was flanked by different genes. The PrMC2-barnaseHlO2E transgenic pine and Eucalyptus (spp.) trees grew similarly to control trees in all observed attributes except the pollenless phenotype. The ability to achieve the complete control of pollen production in field-grown trees is likely the result of a unique combination of three factors: the male cone/anther specificity of the PrMC2 promoter, the reduced RNase activity of barnaseH102E, and unique features associated with a polyploid tapetum. The field performance of the PrMC2-barnaseHlO2E in representative angiosperm and gymnosperm trees indicates that this gene can be used to mitigate pollen-mediated gene flow associated with large-scale deployment of transgenic trees. [ABSTRACT FROM AUTHOR]