Effects of Genetic Variation and Inbreeding on Volatile Production in a Field Population of Horsenettle

Plant volatiles mediate numerous interactions between plants and insects, yet few studies have examined variation in volatile production within plant populations or the genetic and environmental causes of this variation. Here we document the effects of inbreeding and maternal family on volatile production by horsenettle Solanum carolinense L. (Solanaceae). We collected volatiles from ramets (clones) of each of 12 genets (genotypes) of horsenettle grown in four agricultural fields with natural levels of herbivory. The 12 genets included selfand cross-pollinated progeny from six maternal plants. We found that inbreeding reduced total volatile production relative to that of outcrossed plants. We also found a breeding-by-family interaction for the total amount and blend of volatiles, indicating genetic variation among families for inbreeding depression. Analysis of outcrossed plants alone (a random sample from the population) revealed a genet effect on the total amount and blend of volatiles released, indicating broad-sense heritability of volatile traits. Our findings offer insight into the consequences of inbreeding on volatile production and the variation in volatile cues available to foraging insects in a wild plant system. Moreover, we believe this to be the first study demonstrating genetic variation for plant volatiles in a noncultivated species under field conditions.