Genomics / Proteomics
Albouyeh, Rokneddin , Ritland, Kermit .
Phylogenomic analysis of the transcriptome reveals different trends in the evolution of tissue-specific gene expression in spruce.
Excess variation of expression differences among species indicates diversifying selection, while lack of such variation among species indicates purifying selection. Here we present results from the first phase of a phylogeny-driven analysis of spruce transcriptome. The objective of this research is to describe how different modes of evolution shape the patterns of tissue-specific gene expression in spruce. Our transcriptional profiling of five spruce species, using the Treenomix 22 K cDNA microarray platform, found 5128 and 3052 differentially expressed transcripts (Q<0.05) in bark and needle, respectively. In order to create a base line comparison with the neutral theory, we examined the extent of neutral genetic divergence among species using Amplified Fragment Length Polymorphism(AFLP)markers. Needle transcriptome was found to be more phylogenetically congruent to the phylogeny of neutral markers than phloem transcriptome; suggesting that the transcriptome of bark/phloem is evolving under specific selective pressures. Detailed comparisons of the secondary metabolites of defense response between the tissues, we found a meaningful over- representation of the differentially expressed transcripts involved in the phenolics defense in bark/phloem. Of the total 340 transcripts of phenolics photosynthesis spotted on our chip, 150 show differential expression in phloem and 94 in needle tissues (Q<0.05), fitting the concept of increased fitness against pressures from bark borer pests. Ongoing work includes extending the comparisons over the xylem tissue as well as comparison of functional annotation of the other transcript categories between the tissues.
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1 - University of British Columbia, Department of Forest Sciences, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
gene expression evolution.
Presentation Type: Oral Paper:Papers for Topics
Location: 182/I K Barber
Date: Monday, July 28th, 2008
Time: 2:00 PM