Glyphosate is a potent herbicide. It works by competitive inhibition of the enzyme 5-enol-pyruvyl shiki-mate-3-phosphate synthase (EPSPS), which catalyzes an essential step in the aromatic amino acid biosynthetic pathway. We report the genetic engineering of herbicide resistance by stable integration of the petunia EPSPS gene into the tobacco chloroplast genome using the tobacco or universal vector. Southern blot analysis confirms stable integration of the EPSPS gene into all of the chloroplast genomes (5000-10,000 copies per cell) of transgenic plants. Seeds obtained after the first self-cross of transgenic plants germinated and grew normally in the presence of the selectable marker, whereas the control seedlings were bleached. While control plants were extremely sensitive to glyphosate, transgenic plants survived sprays of high concentrations of glyphosate. Chloroplast transformation provides containment of foreign genes because plastid transgenes are not transmitted by pollen. The escape of foreign genes via pollen is a serious environmental concern in nuclear transgenic plants because of the high rates of gene flow from crops to wild weedy relatives. Keywords agricultural biotechnology; transformation; tobacco; glyphosate Glyphosate is a potent, broad spectrum herbicide that is highly effective against a majority of grasses and broad leaf weeds. Glyphosate works by competitive inhibition of the enzyme 5-enol-pyruvyl shikimate-3-phosphate synthase (EPSPS) of the aromatic amino acid biosynthetic pathway. Synthesis of EPSP from shiki-mate-3-phosphate and inorganic phosphate is catalyzed by EPSPS. This particular reaction occurs only in plants and microorganisms, which explains why glyphosate is nontoxic to other living forms. Use of glyphosate is environmentally safe as it is inactivated rapidly in soil, has minimum soil mobility, and degrades to natural products, with little toxicity to non-plant life forms. However, glyphosate lacks selectivity and does not distinguish crops from weeds, thereby restricting its use. EPSPS-based glyphosate resistance has been genetically engineered via the nuclear genome either by the overproduction of the wild-type EPSPS 1 or by the expression of a mutant gene (aroA) encoding glyphosate-resistant EPSPS 2 . *Corresponding author (daniehe@mail.auburn.edu). HHS Public Access Author ManuscriptAuthor Manuscript Author Manuscript Author ManuscriptIn all of the aforementioned examples, without exception, herbicide-resistant genes have been introduced into the nuclear genome. One common concern is the escape of a foreign gene through pollen dispersal from transgenic crop plants engineered for herbicide resistance to their weedy relatives, creating "superweeds." Dispersal of pollen from a central test plot containing transgenic cotton plants to surrounding nontransgenic plants has been observed at varying distances in different directions 3,4 . The escape of foreign genes through pollen is a serious environmental concern, especially in the case of herbicide resistance genes, b...

Using density functional theory, we explore the evolution of the electronic and magnetic properties of BaRuO3 in four different phases, 9R, 4H, 6H and 3C, obtained by synthesizing under different pressure conditions. The four different phases differ in the differential proportion of hexagonal versus cubic close stacking of the BaO3 layers, leading to important changes in the structure. By computing the electronic and magnetic properties of the four different phases, and the optical properties of 4H and 9R phases, we find that density functional based calculations are to a large extent able to explain the change in properties of the four different polytypes.

We report here expression of a protein based polymer gene (Gly-Val-Gly-Val-Pro)m , coding for three amino acids in a pentamer sequence repeated 121 times via the nuclear' ge~ome of tobacco cells. Transformed tobacco cells were obtained by particle bombardment. Stably transformed cells show the presence of the polymer gene in the tobacco nuclear genome (2-5 copies); introduced polymer gene is transcribed efficiently as revealed by Northern blots; Western blots show the presence of the polymer protein. To the best of our knowledge, this report represents the first demonstration of expression of a synthetic gene (with no natural analog) in higher plants.