Effects of inbreeding on plant defenses, volatile production, plant-insect interactions, and the evolution of the breeding system in Solanum carolinense

Many plant species self-pollinate (a severe form of inbreeding) and the leaves of all plant species are damaged by insect herbivores. Both inbreeding and herbivory reduce the growth and reproduction of plants but the effects of inbreeding on plant resistance to herbivores is largely unexplored. The proposed studies will use horsenettle plants to examine differences between inbred and outbred plants in the expression of anti-herbivore genes (using microarrays), the induction of key plant defensive chemicals (using gas chromatography and mass spectrometry) that help to protect the plants from herbivores, and the impact of these defensive chemicals on the feeding behavior of herbivores and their natural enemies (predatory insects).

Horsenettle is a close relative of crop species such as tomatoes, potatoes, eggplant, and peppers and it shares many of the same insect herbivores as these crops. Horsenettle, however, is a widespread invasive weed that is a problem in 43 states. It is an important weed in agricultural fields and it harbors pests and diseases that reduce the yield of these crop species. In addition to producing a complete study of the effects of inbreeding on plant resistance, the proposed research will produce critical information on the colonization and establishment stages of the life cycle of this important weed; provide insight into potential biocontrol agents of horsenettle; and elucidate the potential roles of chemical defenses in the development of sustainable management strategies informed by a sophisticated understanding of underlying genetic and chemical mechanisms.