Guerinot, ML

Science (Washington) [Science (Wash.)], vol. 287, no. 5451, pp. 241-243, 14 Jan 2000

For millennia, breeders have concentrated on modifying the traits of plants to influence their growth performance in the field. The late 20th-century version of this effort is the production of transgenic plants. Crops such as Roundup Ready soybeans developed by Monsanto and corn expressing Bacillus thuringiensis (Bt) toxin reduce costs to the farmer by minimizing the application of herbicides and insecticides. Other genetically engineered traits increase the cash value of a crop providing us, for example, with canola plants that produce oils high in unsaturated fatty acids. However, the crops that would make the biggest difference for the largest number of people in the world are those that would serve as better sources of essential nutrients. Because extreme poverty continues to limit access of much of the world's population to food, it is important that affordable food be as nutritious as possible. The report on page 303 of this issue by Ye et al., who engineered rice grains to produce provitamin A ( beta -carotene), exemplifies the best that agricultural biotechnology has to offer a world whose population is predicted to reach 7 billion by 2013.

Ye, Xudong; Al-Babili, S; Kloeti, A; Zhang, Jing; Lucca, P; Beyer, P; Potrykus, I*

Science (Washington) [Science (Wash.)], vol. 287, no. 5451, pp. 303-305, 14 Jan 2000

Rice (Oriza sativa), a major staple food, is usually milled to remove the oil-rich aleurone layer that turns rancid upon storage, especially in tropical areas. The remaining edible part of rice grains, the endosperm, lacks several essential nutrients, such as provitamin A. Thus, predominant rice consumption promotes vitamin A deficiency, a serious public health problem in at least 26 countries, including highly populated areas of Asia, Africa, and Latin America. Recombinant DNA technology was used to improve its nutritional value in this respect. A combination of transgenes enabled biosynthesis of provitamin A in the endosperm.

Datta, A; Raina, A; Biswas, S

US Patent 5670635, 23 Sep 1997

The present invention relates, in general to protein that is a seed storage protein having high nutritional value. In particular, the invention relates to the protein AmA1 and to a DNA sequence encoding same. The invention further relates to a recombinant molecule comprising the AmA1 encoding sequence and to a host cell transformed therewith. In addition, the invention relates to a method for producing transgenic plants with high nutritionally rich amino acids.

Chong, DKX; Roberts, W; Arakawa, T; Illes, K; Bagi, G; Slattery, CW; Langridge, WHR*

Transgenic Research [TRANSGEN. RES.], vol. 6, no. 4, pp. 289-296, Jul 1997

A 1177 bp cDNA fragment encoding the human milk protein beta -casein was introduced into Solanum tuberosum cells under control of the auxin-inducible, bidirectional mannopine synthase (mas1',2') promoters using Agrobacterium tumefaciens-mediated leaf disc transformation methods. Antibiotic-resistant plants were regenerated and transformants selected based on luciferase activity carried by the expression vector containing the human beta -casein cDNA. The presence of human beta -casein cDNA in the plant genome was detected by PCR and DNA hybridization experiments. Human beta -casein mRNA was identified in leaf tissues of transgenic plants by RT-PCR analysis. Human beta -casein was identified in auxin-induced leaf and tuber tissues of transformed potato plants by immunoprecipitation and immunoblot analysis. Human beta -casein produced in transgenic plants migrated in polyacrylamide gels as a single band with an approximate molecular mass of 30 kDa. Immunoblot experiments identified approximately 0.01% of the total soluble protein of transgenic potato leaf tissue as beta -casein. The above experiments demonstrate the expression of human milk beta -casein as part of an edible food plant. These findings open the way for reconstitution of human milk in edible plants for replacement of bovine milk in baby foods for general improvement of infant nutrition, and for prevention of gastric and intestinal diseases in children.

Burkhardt, PK; Beyer, P; Wuenn, J; Kloeti, A; Armstrong, GA; Schledz, M; Von Lintig, J; Potrykus, I

Plant Journal [PLANT J.], vol. 11, no. 5, pp. 1071-1078, May 1997

Rice (Oryza sativa L.), the major food staple for more than two billion people, contains neither beta -carotene (provitamin A) nor C sub(40) carotenoid precursors thereof in its endosperm. To improve the nutritional value of rice, genetic engineering was chosen as a means to introduce the ability to make beta -carotene into rice endosperm tissue. Investigation of the biochemical properties of immature rice endosperm using [ super(14)C]-labelled substrates revealed the presence of geranyl geranyl diphosphate, the C sub(20) general isoprenoid precursor necessary for C sub(40) carotenoid biosynthesis. Phytoene synthase, which condenses two molecules of geranyl geranyl diphosphate, is the first of four specific enzymes necessary for beta -carotene biosynthesis in plants. Therefore, the Japonica rice model variety Taipei 309 was transformed by microprojectile bombardment with a cDNA coding for phytoene synthase from daffodil (Narcissus Pseudonarcissus) under the control of either a constitutive or an endosperm-specific promoter. In transgenic rice plants, the daffodil enzyme is active, as measured by the in vivo accumulation of phytoene in rice endosperm. Thus, it is demonstrated for the first time that it is in principle possible to engineer a critical step in provitamin A biosynthesis in a non-photosynthetic, carotenoid-lacking plant tissue. These results have important implications for long-term prospects of overcoming worldwide vitamin A deficiency.

US Patent 5559223, 24 Sep 1996

There is provided synthetic nucleic acid fragments for the altered expression of selected nutritionally-important proteins in plants. These nucleic acid fragments may be used to transform plants, particularly crop plants, to increase the lysine and methionine content of seeds or leaves. The invention is of significant interest for the nutritional improvement of corn which is low in lysine and sulfur amino acid-poor plants, such as corn and soybean. There is also provided chimeric genes, host cells, plants, seeds and microorganisms containing the nucleic acid fragment as well as methods for obtaining the expression of particular proteins in plants and microorganisms.

Kinney, AJ

Nature Biotechnology [NAT. BIOTECHNOL.], vol. 14, no. 8, p. 946, Aug 1996

The genetic engineering of the fatty acid composition of plants has become a reality. With the right genes and promoters, it is now possible to redesign the fatty acid profile of either plant membranes or plant storage oils. In this issue of Nature Biotechnology, Toguri and colleagues (pp 1003-1006) describe the expression in tobacco of a cyanobacterial desaturase that introduces a double bond into the Delta 9 position of 16-chain and 18-chain saturated fatty acids. In their transgenic tobacco, there is significant reduction in saturates in both leaf and root, an effect that they correlate with an increased chilling resistance of the plants.