The rhizosphere is teemed with organisms intimately associating with plant roots, including those of other plants. Most of these interactions are mediated through chemicals released by one of the players and perceived by another. The most commonly studied chemical interactions between plants are allelopathic processes by which a plant releases phytotoxins that inhibit the growth of neighboring plants. We are investigating a plant-plant interaction system that uses allelopathic-like molecules and processes but to different purposes: that of host plant recognition by parasitic angiosperms.
We study plant parasitism in the Orobanchaceae, a family of root parasites that includes some of the world’s worst agricultural pests, notably Striga and Orobanche. Because of the invasive potential of weedy Orobanchaceae, we use the closely related parasite Triphysaria as an experimental organism. The Orobanchaceae use chemical and tactile stimuli provided by host roots to initiate the development of haustoria, parasitic plant specific organs used to attach to and invade host roots. The competence to develop haustoria is the key character of parasitic plants and enables them to adapt a heterotrophic lifestyle.
We are taking genomic approaches to define the genetic processes regulating haustorium growth and function. Once candidate parasite genes are identified, their functions are evaluated in transgenic parasite roots. Genes identified as critical for parasite survival are being incorporated into an RNAi based strategy for developing parasitic weed resistant crops.
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