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Genetically modified cotton lines have been developed that are tolerant to glyphosate, the active ingredient in the herbicide Roundup. The new lines were generated by Agrobacterium tumfaciens-mediated transfer of a gene encoding 5-enolpyruvylshikimate-3-phosphate synthase isolated from Agrobacterium sp. CP4 (CP4 EPSPS). Lines were screened via greenhouse spray tests and field evaluations to identify agronomically acceptable lines with a commercial level of tolerance to glyphosate. Two lines were characterized. Lines 1445 and 1698 were transformed with different vectors that encode for the CP4 EPSPS and the neomycin phosphotransferase II (NPTII) marker protein. Both lines contain a single DNA insertion that segregates in a typical Mendelian fashion. Line 1445 contains a single copy of the CP4 EPSPS gene, whereas the line 1698 contains two copies of the CP4 EPSPS gene at a single insertion site. The stability of each DNA insertion was demonstrated by Southern analysis across the R3 and R5 generations. The expression levels of the CP4 EPSPS and NPTII were quantitated by ELISA in leaf and seed samples collected in 1993 and 1994 field trials. The use of glyphosate-tolerant cotton will enable the grower to take advantage of additional weed management alternatives. Keywords: Cotton; genetically modified; herbicide tolerant; Roundup

Anther-culture response was examined among three spring wheat (Triticum aestivum L.) cultivars to evaluate the genetic component of response and to determine whether androgenetic performance could be improved by selection. The three lines, the three possible F1's among the three lines, their F2's, and the backcrosses to the parents were evaluated for callus production and regeneration capacity. Significant variation was observed among the generations of the three crosses for callus formation. Genetic variation for regenerability was nonsignificant. Callus production was negatively correlated (-0.24) with regeneration capacity. The random variation in the study was too great to determine whether major-gene differences for antherculture response exist among the three lines by examining population distributions. When the material was evaluated for quantitative gene effects, the estimates for the additive gene effects were generally greater than the estimates for the dominance gene effects for callus formation. Only the Pavon x Chris cross, however, exhibited a significant narrow sense heritability estimate for callusing response (0.94). Due to the large component of random variation and the varying selection potential among crosses for androgenetic performance, improving anther-culture response in wheat by selection could prove difficult unless the anther-culture process itself selects for response traits at the gametic level.

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Crop yield and quality could be affected in transgenic crop plants carrying foreign genes which confer resistance to plant pests. Scientists at Monsanto Company produced nine transgenic cotton (Gossypium hirsutum L.) lines, each containing one of the two Bacillus thuringiensis var. kurstaki (Berliner) constructs, cryIA(b) or cryIA(c), that encode a protein toxic to lepidopteran insects. We undertook this study to determine whether these transgenic lines exhibit any undesirable agronomic or fiber properties. At Maricopa, AZ, we grew five, four, and three transgenic lines in field plots in 1990, 1991, and 1992, respectively; the parental ‘Coker 312’ and the locally adapted, nectariless, high fiber‐strength ‘Md 51 ne’ were included each year. Somaclonal variation, insertion of the insect‐control protein genes, and the expression of the insecticidal protein caused no general reduction in lint yield, primary or secondary yield components, or fiber properties. The transgenic lines varied significantly in every trait measured. Mean lint yields over the 3 yr were as follows: transgenic lines, 135.4 ± 4.5 g m−2; Coker 312, 115.1 ± 7.7 g m−2, MD 51 ne, 141.2 ± 11.4 g m−2. Six of the nine transgenic lines yielded significantly more lint (13–30%) than did Coker 312. Lint yields of the same six lines (10% less to 7% more) were not significantly different than that of MD 51 ne. Compared with Coker 312, four of nine transgenic lines had longer fiber, eight had stronger fiber, two had higher fiber elongation, and two did not differ significantly in micronaire. Compared with MD 51 ne, five of the nine transgenic lines did not differ significantly in fiber length, two did not differ in strength, three did not differ in elongation, and six did not differ in micronaire. These transgenic lines are valuable sources of germplasm, not only for insect resistance but also for agronomic and fiber properties.