5.3.28
GENE THERAPY FOR PLANTS

SM HAKIMI, ST CASTRO, J LIANG, CA ROSENBERGER, JD BERG, JS ANDERSON and KA BARTON

Monsanto Company, 700 Chesterfield Parkway North, Chesterfield, MO 63198, USA

Background and objectives
Monsanto Life Sciences Company is a leader in the development of novel solutions for the control of plant diseases through the use of chemistry, classical breeding and biotechnology. Plant biotechnology has advanced rapidly in recent years, and Monsanto has now genetically altered many crops with desirable agronomic features including herbicide, insect and disease resistance. Such transgenic crops are now contributing to the evolution toward safer and more efficient agricultural practices. Within the Disease Control Program at Monsanto is a diversified biotechnology team dedicated to the discovery and development of novel antifungal proteins to be used in the control of plant diseases. This team is focused on many important diseases of major crops. The objective of this research is to develop transgenic technology which will enable transfer of fungal disease resistance to wheat and potato varieties which have otherwise excellent agronomic and processing qualities.

Results and conclusions
Monsanto scientists are creating transgenic plants that are resistant to various fungal diseases by transferring antifungal protein (AFP) genes into the plant genome. A number of such AFPs isolated from plant and microbial sources exhibited strong antifungal activities against Fusarium spp. [1], F. culmorum and F. graminearum), Verticillium dahliae, and other fungal pathogens. The genes for several of these proteins have been cloned and transferred into a number of plant species including potato and wheat. Transgenic wheat plants expressing specific AFPs have been tested in both the greenhouse and field for Fusarium head blight (FHB) control. Results indicated that AFP genes confer significant resistance to FHB. Selected lines are now undergoing analysis to determine levels of resistance to other major wheat fungal diseases. In potato, the same antifungal proteins conferred resistance to early dying caused by V. dahliae in 1997 field trials. In both fumigated and infested soils, transgenic potato expressing specific AFPs had consistently lower disease ratings over the season compared to the negative control Russet-Burbank. In both field and greenhouse, several antifungal protein transgenic potato clones meet or exceed our disease control criteria.

References
1. Rowe RC et al., 1987. Plant Disease 71, 482-489.
2. Gilbert J et al., 1997. Plant Disease 81, 159-162.