title: The molecular bases of floral scent evolution under artificial selection: insights from a transcriptome analysis in Brassica rapa.
abstract: In an artificial selection experiment using fast-cycling Brassica rapa plants it was recently shown that floral VOCs respond rapidly to selection for increased amounts. Here we carried out transcriptome analysis in these plants to explore the molecular bases of the augmentation in the artificially selected scent compound, phenylacetaldehyde (PAA), as well as other compounds that increased through pleiotropy. In the transcriptome data, we found up-regulation of genes likely underlying PAA synthesis, but also several genes of the shikimate pathway and the related phenylalanine metabolism. As phenylalanine is the precursor of many aromatic volatiles that showed increased emission, this result could explain some of the pleiotropic evolutionary responses. In addition, we found that ribosomal protein genes were up-regulated in "high" (high PAA amount) selection line plants, a mechanism that might further augment the effect of elevated gene expression at the proteomic level. Our study shows that selection on an individual trait can impose changes in the expression of several different genes, which could explain pleiotropic responses in the biosynthetic network of floral volatiles.
authors.affiliation: Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
authors.forename: Jing
authors.initials: J
authors.lastname: Cai
authors.affiliation: Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
authors.forename: Pengjuan
authors.initials: P
authors.lastname: Zu
authors.affiliation: Department of Systematic and Evolutionary Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
authors.forename: Florian P
authors.initials: FP
authors.lastname: Schiestl
mesh_terms: D000079:Acetaldehyde / Q000031:analogs & derivatives* / Q000378:metabolism; D029741:Brassica rapa / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling / Q000379:methods*; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D058685:Genetic Pleiotropy; D010940:Plant Proteins / Q000235:genetics*; D055549:Volatile Organic Compounds / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D055549:Volatile Organic Compounds; D000079:Acetaldehyde; C013192:phenylacetaldehyde