The Genetic and Epigenetic Basis of Trichome Production in Yellow Monkeyflower (Mimulus guttatus)

Trichomes are sticky leaf hairs that protect Mimulus guttatus (yellow monkeyflower) from insect herbivory. Trichome production is plastic, meaning plants produce more trichomes on new leaves in response to damage. Progeny of damaged mothers show increased trichome production even without damage, a phenomenon known as epigenetic inheritance. The genes and developmental pathways involved in Mimulus trichome production are not well understood. Constitutive trichome production and plasticity in response to damage was measured in two populations selected for high baseline trichome production and in two control populations. Plants in the selected populations showed significantly higher baseline trichome production. They also showed decreased plasticity, which is in accordance with optimal defense theory. Pooled DNA samples from each population were sequenced using next-generation sequencing technology and the data analyzed to find regions of the genome associated with trichome production. Multiple regions of the chromosomes showed response to selection for high trichomes, which is indicative of polygenic inheritance. These regions are concordant with the results of a related quantitative trait loci (QTL) mapping analysis. Epigenetic inheritance will be measured in future experiments. Understanding the genetics of an ecologically relevant trait not only provides greater understanding of how organisms interact with biotic factors in their environment, but it also provides more information on an emerging model organism