A determining factor for the success of saplings maturing
into healthy trees is their hardiness. Indeed, one of the
major tasks for nursery growers consists of hardening plants,
or preparing them for the harsh and often varying conditions
they will face in natural environments. Hardiness, and particularly
cold hardiness for European purposes, is important for forestry
officials coordinating reforestation efforts across the continent.
A successfully completed research project funded under FP5
attempted to identify the genetic root of tree hardiness to
support reforestation rates and the vitality of economically
and ecologically important forest tree species.
The FP5 project COLDTREE investigated the molecular processes underlying winter hardiness in an effort to develop state-of-the-art tools assessing the condition of young trees. With the newly developed tools, researchers hoped to evaluate the probability of a seedling surviving winter conditions.
research is helping to identify trees' natural
defences against the cold.
© Hilkka Pellikka
The project consortium used cDNA microarray technology to analyse
gene expression patterns in sample trees. Experts combined gene
expression technology with physiological and morphological screening
for a multidisciplinary approach to the molecular events involved
at the onset and release of dormancy and hardiness.
Once researchers were able to single out those genes with a
strong predictive value, the genes were selected to be used
in trees for nursery management and as an aid in improving forestation
COLDTREE participants tested their model through two seasons using both field-grown and controlled growth pine and beech trees. They were able to produce a series of physiologically well-defined samples spanning the whole period of dormancy and cold hardiness development.
During controlled growth, tree sample groups were studied separately for decreasing temperature environments and decreasing day-length environments to allow an independent study of genes involved in these intertwined but discrete processes. Cold and warm shocks were applied, though they were shown to hardly influence tree dormancy.
Through their innovative interdisciplinary model, experts were able to determine that dormancy development in beech is more pronounced than that of pine. They compiled a cDNA library from beech buds to be used as a base for a small beech array in future studies.
The consortium also carried out work on the development of an
easy-to-use diagnostic test using dehydrin genes as a model.
Dehydrins code for proteins present throughout the plant kingdom
allowing the test to be used beyond forestry. The proteins generated
by dehydrins play important roles in dormancy and defence against
dehydration and other abiotic stresses making them important
subjects of study for researchers protecting plants from today's