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After the book - Progress in parasitic plant research since Kuijt's Biology of Parasitic Flowering Plants (1969)

Westwood, James [1].

Molecular Biology of Parasitism in Orobanche.

Among the most intriguing aspects of parasitic plant development is the integration of the haustorium into the host root. For the past several years we have been studying molecular aspects of this process, beginning with the expression of host genes in response to parasitism, and subsequent use of parasite-inducible promoters to engineer parasite-resistant hosts. Analysis of host gene expression following parasitism indicates that Orobanche triggers the host to activate some defense responses more than others. Specifically, Orobanche induces defenses associated with the localized production of phytoalexins much more than those associated with salicylic acid (SA) signaling, pathogenesis-related (PR) proteins, and systemic acquired resistance. One strategy for resistance has been to try to artificially stimulate these SA-mediated defenses that are not normally activated by the parasite. This was done by engineering components of a parasite-triggered hypersensitive response (HR) in tobacco, which resulted in decreased parasitism in transgenic plants as compared to non-transformed controls. We have also taken a very different approach to engineering resistance by using sarcotoxin IA, an antibacterial peptide. The gene encoding this peptide was fused to a parasite-inducible promoter and transformed into tobacco. The resulting transgenic plants exhibited greater biomass accumulation and reduced levels of parasitism as compared to non-transgenic plants when grown in Orobanche-inoculated soil. Investigations into the mechanism of sarcotoxin toxicity to the parasite have documented the host-to-parasite movement of protein and macromolecules that are larger than sarcotoxin IA (4 kDa). Studies such as these are expanding our understanding of parasitic plant biology as we work toward the ultimate goal of protecting crops from these devastating weeds.

1 - Virginia Tech, Plant Pathology, Physiology and Weed Science, 410 Price Hall, Blacksburg, Virginia, 24061-0331, USA

Genetic engineering
Parasitic plant.

Presentation Type: Symposium
Session: 4-4
Location: Ballroom 2 (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 9:45 AM
Abstract ID:282

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