background of growth and resistance
members: Ass .Prof. Ann-Christin
Associated to the project: Ass.
Prof. Sofia Berlin Kolm (SAMBA1&2),
Dr. Henrik Hallingbäck (SAMBA2),
Per Sjödin (SAMBA2), Dr.
Margareta Aili (SAMBA1), Dr. Luisa Ghelardini (SAMBA1),
Ingrid Eriksson (SAMBA1), Yvonne
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.
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
growth cessation in the phytotrone.
(printable): Genetic background, Linkage maps