PARENT SESSION
Poster Session #4: Herbivory.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Genetic determinants of condensed tannins in aspen.

Stevens, Michael^*,1, Lindroth, Richard¹, ¹ University of Wisconsin-Madison, Madison, WI

ABSTRACT- Tannins are phenolic derivatives of the shikimic acid pathway and have broad spectrum activity against viruses, bacteria, fungi, and animals. Tannins are a major component of aspen (Populus tremuloides) leaves, often comprising 25% of dry weight. Aspen is subject to widespread insect and mammalian herbivory. Prior research has shown that tannin levels respond to environmental factors such as light, nutrients, and herbivory. This research was conducted in order to understand genetic controls of condensed tannin levels using aspen as a model system. We used leaf material from 121 trees of known parentage and gender in 6 full-sibling families planted in northern Wisconsin in 1958 and 1965. The trees in our study were produced from various controlled crosses between parent trees which are still available. We assayed condensed tannins using the acid butanol technique. Tannin levels were not related to tree gender (R² = 0.00, p= 0.91; female average = 18.8%, male average = 19.1% (dry weight)), but did vary significantly among families (R² = 0.25, p = 0.00). Regression analyses of offspring tannin levels against parent levels showed low to moderate (0.17) narrow-sense heritability (h²) and that levels of condensed tannins were more dependent on male (h² = 0.43) than female parents (h² = 0.12). Understanding genetic determinants of plant chemistry will help to better predict how plants will respond to selective pressures from herbivores and a changing environment.

KEY WORDS: tannins, aspen , heritability, gender