Inheritance and expression of foreign genes in transgenic soybean plants

Abstract

DNA-coated gold particles were introduced into meristems of immature soybean seeds using electric discharge particle acceleration to produce transgenic fertile soybean plants. The lineages of integrated foreign DNA in two independently transformed plants were followed in the first (R1) and second (R2) generation of self-pollinated progeny. One plant (4615) was transformed with the Escherichia coli genes for 8-glucuronidase and neomycin phosphotransferase II; the other (3993) was transformed only with the gene for 18-glucuronidase. Segregation ratios for the introduced gene(s) were approximately 3:1 for plant 4615 and 1:1 for plant 3993 in the R1 generation. DNA analysis showed 100% concordance between presence of the foreign gene sequences and enzyme activity. Moreover, all copies of the foreign genes are inherited as a unit in each plant. Plant 3993 segregated in a 1:1 ratio in the R2 generation. RI plants derived from plant 4615, which expressed both genes, gave either 100% or 3:1 expression of both genes in the R2 generation, demonstrating recovery of both homozygous and heterozygous R, plants. Our results show that foreign DNA introduced into soybean plants using electric discharge particle acceleration can be inherited in a Mendelian manner. Results also demonstrate cotransformation of tandem markers and show that both markers are inherited as closely linked genes in subsequent generations. These results indicate that whole plants can be derived from single transformed cells by a de novo organogenic pathway.Technologies are being developed to transform the more important agronomic crops since Agrobacterium-or protoplast-based transformation methods are currently unsuccessful or inefficient with these plants. We described (1) how electric discharge particle acceleration can stably transform a major commercial cultivar of soybean. This method bypasses traditional tissue culture operations involving protoplast and callus cultures and may thereby reduce varietal restrictions and problems of somaclonal variation frequently associated with regeneration of plants from tissue culture. To evaluate and characterize the stability of introduced genes in transgenic plants obtained by this method, the expression and organization of two foreign marker genes were analyzed in sexually derived progeny over two generations. MATERIALS AND METHODSPlasmids. pAcX1100P and pAcX1021P were constructed by inserting the chimeric 8-glucuronidase (GUS) (2) and neomycin phosphotransferase II (NPT II) (3) genes from pCMC1100 (1) and pCMC1021 (4), respectively, into the unique Xho I site ofpAc3 (5). The insertions in these plasmids are oriented such that the direction of transcription is the same as that of the Ac element (6). Plasmids were prepared as described (1).Preparation of DNA and Particle Delivery. DNA-coated gold particles were prepared by mixing equal molar amounts of pAcX1100P, pAcX1021P, and pAc3 with 1.5-pim gold beads at a rate of 1 mg of beads to 0.01-0.1 ;kg of DNA as described (1, 7). Particle delivery into the ta...

Development of a highly efficient, repetitive system of organogenesis in soybean (Glycine max (L.) Merr).

“…Genetic modification has been used for producing varieties with traits that are not available in the soybean gene pool. The regeneration system used to produce genetically modified plants was somatic embryogenesis from immature seeds (Christou et al 1989) or organogenesis from cotyledonary nodes (Finer and McMullen 1991).…”

Expression and inheritance of the wheat Glu-1DX5 gene in transgenic maize

“…A number of plant transformation experiments have reported plants with a mixture of non-Mendelian and Mendelian inheritance of the transgene (Christou et al 1989;Tomes et al 1990;Spencer et al 1992;Walters et al 1992;Hiei et al 1994;Register et al 1994;Peng et al 1995). In our experiments, none of the four events we studied exhibited efficient pollen transmission.…”

Production and Characterization of Transgenic indica Rice Plants Carrying Maize Ac-Ds Elements Introduced by Particle Bombardment.

“…The low transmission of the transgene to the progeny could be due to this phenomenon which was also speculated from the observed 1:1 segregation ratio. Distorted segregation of the transgene has been reported [11,36] but the reason (s) remains unclear.…”

“…Ac line BA9, bearing a single copy of Ac, failed to segregate in a 3:1 ratio. In fact, the observed segregation ratio fitted to 1:1 which indicated either that the transgene was transmitted exclusively through male or female gametes [36], or that elimination of the transgene occurred during meiosis.…”