|SMIGOCKI, ANN - 1275-35-00
Submitted to: American Society of Sugarbeet Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 6/30/1997
Publication Date: N/A
Technical Abstract: Novel molecular genetic approaches are being utilized to enhance defense properties and improve carbon partitioning in sugarbeet. Two approaches are being used to enhance disease resistance, one of them targets pathogenic fungi and bacteria and the other insect pests. For microbial control, genes coding for proteins with defense properties are being utilized (L.D. Owens, USDA, ARS, Plant Molecular Biology Laboratory, Beltsville). These include the small, cysteine-rich proteins that have been shown in other transgenic plants to display varying levels of toxicity to a broad range of plant pathogenic fungi and to some bacterial pathogens. The cecropin MB39, DB4 thionin, osmotin and PR-S (pathogenesis related protein-S, an osmotin-like protein secreted extracellularly in contrast to the vacuole-targeted osmotin) genes were reconstructed to allow expression in different tissues and under specific inducing conditions. Transgenic sugarbeet plants carrying one to two of these genes have been regenerated and are being grown to maturity for seed production and testing for resistance to Erwinia carotovora subsp. betavasculorum, Cercospora beticola and Rhizoctonia solani. For control of insect pests, a novel approach utilizing a gene (isopentenyl transferase, ipt) involved in the synthesis of a major class of plant regulating substances, the cytokinins, is being used. The gene was engineered to allow for induction of its expression upon insect feeding or mechanical wounding or to be expressed specifically in the sugarbeet taproot. Using this approach, enhanced resistance to tomato hornworm and a virus-transmitting pest, the green peach aphid, was demonstrated in other transgenic plants.