Recent Topics Posters
Dick, Cindy , Buenrostro, Jason , Butler, Tim , Cossentine, Heidi , Hamilton, Savannah , Munsen, Rachel , Portilla, Mimi , Schneider, Keith , Storelli, Beth , Kliebenstein, Dan , Carlson, Matthew , Whittall, Justen B. .
The Metabolomic and Molecular Basis of Flower Color Diversity in the Arctic Mustard Parrya nudicaulis.
Most morphological changes are likely due to changes in gene expression rather than mutations in structural genes. The relative frequency of regulatory versus structural mutations should be proportional to the target size of candidate loci constrained by negative pleiotropic effects of changes in those loci. The role of pleiotropic constraints will be particularly important during loss-of-function mutations in stressful environments. Thus, we investigated the purple-white flower color polymorphism in the Arctic mustard, Parrya nudicaulis (Brassicaceae) to examine the predicted pleiotropic constraints on the early genes in the anthocyanin biosynthetic pathway (ABP) in the challenging Arctic environment. We used metabolomic profiling and molecular analysis of the purple and white morphs to determine the location in the pathway and the role of structural and regulatory changes underlying this polymorphism. Purple morphs produce the anthocyanin cyanidin plus a diversity of flavonoid intermediates especially the flavonol, quercetin. Comparatively, white morphs produce no detectable anthocyanins, nor any flavonoid intermediates suggesting the loss-of-function must be upstream from the genes responsible for producing flavonols. Isolation of the six ABP structural genes from cDNA of petal tissue from purple morphs revealed only a single copy of each gene was expressed at three developmental stages. Sequence comparisons of these loci from white petal cDNA revealed no color-specific alleles for any of the six structural genes. By not finding any loss-of-function mutations, nor any substitutions consistently linked with the white phenotype, it is unlikely that structural mutations, nor regulatory changes in the promoter region linked to the structural gene (cis-regulatory elements), are causing the white phenotype. Additional sequencing of the remaining coding region and promoter regions is necessary to confidently exclude structural and cis-regulatory regions. We are actively pursuing quantitative PCR analysis of the six structural loci to test for tissue specific expression differences between purple and white morphs across the ABP.
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Whittall's Lab Website
1 - Santa Clara Unviersity, Biology Department, 500 El Camino Real
2 - Santa Clara University, Biology Department, 500 El Camino Real, Santa Clara, CA, 95053, USA
3 - Santa Clara Unviersity, Biology Department, 500 El Camino Real, Santa Clara, CA, 95053, USA
4 - University of Alaska, Biological Sciences Department, Anchorage, AK, 99501, USA
5 - University of California, Department of Plant Sciences, One Shields Ave., Davis, CA, 95616, USA
Presentation Type: Recent Topics Poster
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM