Victoria Borowicz

Parasitic and Mutualistic Interactions Involving Plants

In nature, plants are besieged by a variety of enemies, including herbivores, pathogens, and parasitic plants. I am interested in the impact of enemies on plants, how symbionts affect their hosts and the enemies of the host, and how the environment alters the role played by symbionts.

Figure 1. Some of the interactions among plants, their enemies, and mutualists. Solid lines indicate direct interactions between the host and another species. Dashed lines indicate indirect interactions between two species that are mediated by the host plant. Arrows point towards the organism that is affected and sign indicates the nature of the effect.

Hemiparasites are photosynthetic plants that tap into the vascular tissue of neighboring plants and rob them of water and minerals, reducing host growth and changing competitive relations. Many factors shape the impact of parasitic plants on hosts and growth of the parasite. Dr. Joe Armstrong and I have recruited a number of undergraduate students to assist in a collaborative long-term field experiment that examines two abiotic factors. This experiment tests how nutrient enrichment and shade alter the impact of Pedicularis canadensis on prairie community productivity and composition, and how these environmental factors affect growth of this hemiparasite. Other research is focused on relationships between parasitic plants, host plants, and herbivores of the host.

Our field site, a restored prairie, has been invaded by an aggressive exotic legume. Two honors students helped us take baseline data in 2010 for an experiment to test different control techniques for inhibiting invasion. We are cooperating with the McLean County Park Service to develop a protocol for monitoring and managing this site.

I also examine how arbuscular mycorrhizal fungi (AMF) reduce or exacerbate effects of enemies such as herbivores. The roots of most plant species are colonized by these symbionts, which are well known for improving nutrient and water relations of their host plants. However, AMF also consume carbon fixed by the host. By changing the plant’s carbon:nutrient balance, AMF may indirectly affect the growth of insects feeding on the plant or the ability of the plant to continue to grow when damaged.

Selected Publications:

Borowicz, V.A. 2010. The impact of arbuscular mycorrhizal fungi on strawberry tolerance to root damage and drought stress. Pediobiologia 53:265-270.

Borowicz, V. A. 2009. Organic farm soil improves strawberry growth but does not diminish spittlebug damage. Journal of Sustainable Agriculture 33:1-12.

Borowicz, V.A. 2006. When enemies attack do plants get by with a little help from their friends? Commentary New Phytologist 169:644-646.

Hedberg, A.M., V.A. Borowicz, & J.E. Armstrong. 2005. Interactions between a hemiparasitic plant, Pedicularis canadensis L. (Orobanchaceae), and members of a tallgrass prairie community. Journal of the Torrey Botanical Society 132:401-410.

Borowicz, V.A., U. Albrecht, & R.T. Mayer. 2003. Effects of nutrient supply on citrus resistance to root herbivory. Environmental Entomology 32:1242-1250.

Borowicz, V.A. 2001. Do arbuscular mycorrhizal fungi alter plant-pathogen relations? Ecology 82:3057-3068.

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