Project description:Gene copy number variation (CNV) is a form of genetic polymorphism that contributes significantly to genome size and function but remains poorly characterized due to technological limitations. Inter-specific comparisons of CNVs in recently diverged plant species are crucial to uncover selection patterns underlying adaptation of a species to stressful environments. Especially given that gene amplifications have long been implicated in emergence of species-specific traits, we conducted a genome-wide survey to identify species-specific gene copy number expansions and deletions in the model extremophile species - Arabidopsis halleri that has diverged in evolutionarily recent time from Arabidopsis thaliana. Cross-species cDNA array based comparative genomic hybridization was employed to compare and identify gene copy number variation in the two sister-species - the metallophyte Arabidopsis halleri and non-metallophyte Arabidopsis lyrata, both relative to Arabidopsis thaliana. We uncovered an unprecedented level of gene copy number polymorphism in Arabidopsis halleri, with a species-specific enrichment of metal homeostasis function in the genes found to be copy number expanded, thus indicating CNV as a mechanism that underlies the key physiological trait of metal hyperaccumulation and hypetolerance in A. halleri.
Project description:Arabidopsis thaliana is a well-established model system for the analysis of the basic physiological and metabolic pathways of plants. The presented model is a new semi-quantitative mathematical model of the metabolism of Arabidopsis thaliana. The Petri net formalism was used to express the complex reaction system in a mathematically unique manner. To verify the model for correctness and consistency concepts of network decomposition and network reduction such as transition invariants, common transition pairs, and invariant transition pairs were applied. Based on recent knowledge from literature, including the Calvin cycle, glycolysis and citric acid cycle, glyoxylate cycle, urea cycle, sucrose synthesis, and the starch metabolism, the core metabolism of Arabidopsis thaliana was formulated. Each reaction (transition) is experimentally proven. The complete Petri net model consists of 134 metabolites, represented by places, and 243 reactions, represented by transitions. Places and transitions are connected via 572 edges.
Project description:We developed an artificial genome evolution system, which we termed ‘TAQing’, by introducing multiple genomic DNA double-strand breaks using a heat-activatable endonuclease in Arabidopsis plant. The heat-activated endonuclease, TaqI, induced random DSBs, which resulted in diverse types of chromosomal rearrangements including translocations. To evaluate the potential of TAQing in multicellular organisms, we tested it in diploid and tetraploid Arabidopsis plants. In 9 out of 96 TQ4 plants, we detected 22 large copy number variations (CNVs) events compared witn wild type plant genome, whereas no CNV was found in the 16 control tetraploid plants, and 12 TQ2 plants. The combination of artificially introduced DSBs with whole-genome duplication (WGD) in plants enabled more complex genome reorganization.
Project description:A major effort is underway to study the natural variation within the model plant species, Arabidopsis thaliana. Much of this effort is focused on genome resequencing, however the translation of genotype to phenotype will be largely effected through variations within the transcriptomes at the sequence and expression levels. To examine the cross-talk between natural variation in genomes and transcriptomes, we have examined the transcriptomes of three divergent A. thaliana accessions using tiling arrays. Combined with genome resequencing efforts, we were able to adjust the tiling array datasets to account for polymorphisms between the accessions and therefore gain a more accurate comparison of the transcriptomes. The corrected results for the transcriptomes allowed us to correlate higher gene polymorphism with greater variation in transcript level among the accessions. Our results demonstrate the utility of combining genomic data with tiling arrays to assay non-reference accession transcriptomes.