Transgenic plants have become attractive systems for production of human therapeutic proteins because of the reduced risk of mammalian viral contaminants, the ability to do large scale-up at low cost, and the low maintenance requirements. Here we report a feasibility study for production of a human therapeutic protein through transplastomic transformation technology, which has the additional advantage of increased biological containment by apparent elimination of the transmission of transgenes through pollen. We show that chloroplasts can express a secretory protein, human somatotropin, in a soluble, biologically active, disulfide-bonded form. High concentrations of recombinant protein accumulation are observed (>7% total soluble protein), more than 300-fold higher than a similar gene expressed using a nuclear transgenic approach. The plastid-expressed somatotropin is nearly devoid of complex post-translational modifications, effectively increasing the amount of usable recombinant protein. We also describe approaches to obtain a somatotropin with a non-methionine N terminus, similar to the native human protein. The results indicate that chloroplasts are a highly efficient vehicle for the potential production of pharmaceutical proteins in plants.

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This chapter examines the current management strategies and their limitations in USA maize production and the potential benefits of managing these pests with a developed corn rootworm (Diabrotica spp.)-protected maize. The topics covered include development of a genetic solution for corn rootworm management, characterization of YieldGard rootworm maize, food and feed safety of YieldGard rootworm maize, environmental safety of YieldGard rootworm maize, performance of YieldGard rootworm maize, and benefits of YieldGard rootworm maize.

Genetically modified (GM) crops currently constitute a significant and growing part of agriculture. An important aspect of GM crop adoption is to demonstrate safety and equivalence with respect to conventional crops. Untargeted metabolomics has the ability to profile diverse classes of metabolites and thus could be an adjunct for GM crop substantial equivalence assessment. To account for environmental effects and introgression of GM traits into diverse genetic backgrounds, we propose that the assessment for GM crop metabolic composition should be understood within the context of the natural variation for the crop. Using a non-targeted metabolomics platform, we profiled 169 metabolites and established their dynamic ranges from the seeds of 49 conventional soybean lines representing the current commercial genetic diversity. We further demonstrated that the metabolome of a GM line had no significant deviation from natural variation within the soybean metabolome, with the exception of changes in the targeted engineered pathway.

1. A 2-year field study was conducted in 2000 and 2001 at a farm in Monmouth, Illinois to evaluate the effect of MON 863, a transgenic corn event that expresses the Cry3Bb1 protein for control of corn rootworms, on diverse groups of arthropod populations in a corn ecosystem.2. The field study employed a split-plot design with MON 863 and conventional corn as the main plots and several insecticide treatments as subplots; each main plot was replicated four times (i.e. n = 4 block replications for each corn variety). A large number of arthropod taxa were trapped, taxonomically characterised, and counted in all plots. A mixed linear repeated-measures model was used for analysis of each taxon collected to determine if there was an effect of MON 863 or insecticide regime on that taxonomic group.3. This report describes the results of a power analysis to determine the ability of the study design to detect an effect of MON 863 corn on the abundance of different groups of arthropods. A 50% difference in average taxon abundance between MON 863 and conventional corn plots was the criterion used in assessing the power. 4. A statistical power analysis of the taxonomic group comparisons made in the 2-year field study (with independent assignment of treatments each year) showed that only about 28% (22 of 56) of the statistical comparisons made with single years of data achieved ≥80% power to detect a 50% difference in population density. When data from both years of the study were analysed jointly, this level of power was obtained for 86% (24 of 28) the comparisons made.5. Graphical examination of the mean abundance and coefficient of variation (CV) for different taxa indicated that high abundance (> 5 trap captures per plot per sampling period) and low CV (< 100%) contributed to high statistical power (> 80%). Taxa with extremely low abundance (mean trap captures < 1 individual per plot per sampling period) generally had high CV (> 100%), and statistical comparisons for those taxa had lower power (< 80%).6. The relevance of these findings for designing field studies on the effects of genetically modified crops on non-target arthropods with desired levels of power is discussed.Key words . Biotechnology , corn rootworm control , experimental design , genetically modifi ed corn , non-target effects , statistical power . 522 Jian J. Duan et al.

The enzyme p-hydroxyphenylpyruvate dioxygenase (HPPD) is ubiquitous in plants and functions in the tyrosine catabolic pathway, resulting in the formation of homogentisate. Homogentisate is the aromatic precursor of all plastoquinones and tocochromanols, including tocopherols and tocotrienols. Soybean (Glycine max (L.) Merr.) has been genetically modified to express the gene avhppd-03 that encodes the protein AvHPPD-03 derived from oat (Avena sativa L.). The AvHPPD-03 isozyme has an inherent reduced binding affinity for mesotrione, a herbicide that inhibits the wild-type soybean HPPD enzyme. Expression of avhppd-03 in soybean plants confers a mesotrione-tolerant phenotype. Seeds from three different avhppd-03-expressing soybean events were quantitatively assessed for content of eight vitamin E isoforms. Although increased levels of two tocopherol isoforms were identified for each of the three soybean events, they were within, or not substantially different from, the ranges of these isoforms found in nontransgenic soybean varieties. The increases of these tocopherols in the avhppd-03-expressing soybean events may have a slight benefit with regard to vitamin E nutrition but, given the commercial processing of soybeans, are unlikely to have a material impact on human nutrition with regard to vitamin E concentrations in soybean oil.

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