Molecular Ecology and Evolution
Derieg, Nathan , Hodges, Scott .
Molecular basis of an adaptive trait: floral anthocyanin production in Aquilegia.
Describing the molecular genetic basis of variation in morphological traits is a major component for understanding the process of adaptation and addressing longstanding questions such as whether rapid evolutionary change is predominately facilitated by mutations affecting gene expression or gene function. The North American radiation of Aquilegia (Ranunculaceae) comprises taxa falling into one of three pollination syndromes – bee, hummingbird, or hawkmoth – which are united by shared features of floral morphology. Flower color is one of these adaptive traits and is controlled by a well-characterized portion of the flavonoid biosynthetic pathway (anthocyanin production). To identify the genetic basis of color variation, we searched an Aquilegia EST database, and identified 37 genes with strong similarity to known flavonoid biosynthetic pathway genes. Using rtPCR we also identified two additional R2R3-Myb transcription factors expressed during anthocyanin production in sepals (AqMyb12 & AqMyb17). To determine what subset of the identified genes is involved specifically in floral flavonoid production we used ultra-high-throughput sequencing for transcriptome profiling of A. formosa sepal tissue. This method highlights differential gene expression, e.g., AqMyb12 is expressed at approximately 20X higher levels than AqMyb17 in sepals, and also provides full-length transcript sequence. To identify which gene(s) may be responsible for floral color differences between red-flowered A. formosa and white-flowered A. pubescens we sequenced nine of the anthocyanin biosynthetic genes from 48 individuals in an F2 hybrid population. We identified a strong correlation between genotype and flower color for AqMyb12 and DFR, but these genes are in linkage disequilibrium, which confounds assessing whether only one, or both of these genes affect floral color variation. We plan to sample the entire F2 population (>300 individuals) for variation at all of the identified genes in the flavonoid biosynthetic pathway to fully dissect the genetic basis of this adaptive trait.
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1 - University of California Santa Barbara, Department of Ecology Evolution And Marine Biology, Santa Barbara, California, 93106-9610, USA
anthocyanin biosynthetic pathway
Presentation Type: Oral Paper:Papers for Topics
Location: Maybird/Cliff Lodge - Level C
Date: Tuesday, July 28th, 2009
Time: 8:30 AM