Genetics of climatic adaptation in trees

Plants needs to be well adapted to local conditions as the timing of the onset and release of dormancy is a trade-off between increased growth potential and the risk of frost damage. We know a great deal about the physiology and quantitative genetics of phenology in trees, but the genes that underlie these traits are largely unknown.
Our goal is to:
Elucidate the pathways that react on photoperiod and temperature and control growth rhythm in conifers.
Identify the genes in those pathways that control the adaptation of Norway spruce trees to their local environment.
Establish the degree of conservation of such pathways in angiosperms and gymnosperms.

To answer these questions, we combine functional studies of candidate genes in Picea abies and the model species Arabidopsis thaliana with association mapping and population genetic analysis of the same genes in P. abies


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Genetics of flowering time variation

Flowering time is a trait of considerable adaptive and agricultural value. Molecular and developmental geneticists have defined many of the genes that potentially govern the different flowering time pathways in the model plant Arabidopsis thaliana, mainly through mutational analyses. However, it is still not known what roles the different pathways and the genes within the pathways have in governing flowering time variation in natural populations of A. thaliana or other species, with rare exceptions.

We use a variety of methods to identify genes that control variation in flowering time in several plant species, e.g., A. thaliana, Brassica spp. and Capsella bursa-pastoris. Methods include QTL and association mapping, analysis of gene expression and population genetic analysis of sequence variation.

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Evolution of plant genomes

Previous studies have revealed that plant genome size is highly variable, with frequent polyploidisation in many plant families. Yet the significance of this variation is not clear. More data is needed on the rate of duplication and fate of the resulting duplicates. We use comparative mapping to study the structural evolution of plant genomes, and analyze sequence variation in paralogous genes resulting from various duplication events.

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Evolution of gene expression

Historically, genetic systems have mainly been viewed as protein coding entities. Consequently, the vast majority of the available information on genetic variation is coming from protein-coding regions. However, every gene is embedded among regulatory sequences, that in conjunction with proteins encoded elsewhere, regulate the timing and location of gene expression. Thus, regulatory sequences are important for gene function. Both theoretical and empirical studies also suggest that transcriptional regulation is likely to be an important contributor to intraspecific phenotypic variation and adaptation.

In plants, there is a lack of data on natural variation in gene expression, and even less is known about the functional importance of the existing gene expression variation. We use microarrays to assess global patterns of gene expression variation within and between plant species. To study the functional importance of gene expression we also study expression variation for specific genes involved in control of flowering time and cold acclimation.

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