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Genetic background of growth and resistance

Project members: Ass .Prof. Ann-Christin Rönnberg-Wästljung

Associated to the project: Ass. Prof. Sofia Berlin Kolm (SAMBA1&2), Dr. Henrik Hallingbäck (SAMBA2), Dr. Per Sjödin (SAMBA2), Dr. Margareta Aili (SAMBA1), Dr. Luisa Ghelardini (SAMBA1), Ingrid Eriksson (SAMBA1), Yvonne Tillman (SAMBA1)

To study the genetic background of different traits in Salix we use several approaches. We have developed four mapping populations with many hundreds of individuals based on crossings within species (Salix viminalis) and between two species (S. viminalis x S. schwerinii, and S. purpurea x S. viminalis). For these populations we have constructed genetic linkage maps that we use in quantitative trait loci (QTL) mapping where we connect the trait variation with the genetic variation and the linkage maps. In this way we could identify regions in the Salix genome that with high probability contain candidate genes that regulate the traits. In addition we have, together with researchers at Rothamsted Research in England and Lantmännen SW Seed AB, developed an association mapping population of S. viminalis based on existing clonal material and collections from natural populations. This population is used in genome wide association studies (GWAS) to find associations between a trait and candidate genes. We have used a genotype-by-sequencing (GBS) technique to develop ~20 000 so-called SNP markers and in addition we also use SNP markers in candidate genes identified in earlier QTL studies and from the literature. We study growth traits, phenology traits as bud burst and growth cessation, resource allocation for water and nutrients as well as resistance. The phenotypic variation is studied in different types of experiments in laboratory, greenhouse and field trials.

measurements

Since Salix and Populus are closely related we have been able to use DNA sequence information from Populus to develop SNP markers for the linkage maps in Salix. We have placed markers evenly spread across all chromosomes in the genome and also added markers in candidate genes for resistance and drought tolerance. In specific regions of the genome, which we have identified as important with QTL analysis, we have made the maps much denser with many new SNP markers. The new markers make it easier to locate candidate genes in the sequenced genome of Populus or in the sequence data we have from S. viminalis (see below). To verify that we have found the correct candidate genes we make detailed studies on gene expression.

We have also, with different techniques, sequenced the whole genome of an individual of S. viminalis as well as transcriptomes and are working with the assembly of the sequence data. The genome and transcriptome information will be of great importance in our search for important genes in different traits.
Measurements of growth cessation in the phytotrone.

Download (printable): pdfGenetic background, pdf Linkage maps

 

Updated 2017-02-23 |Berit Samils