During evolution, plants have developed a numerous sophisticated mechanisms how to cope with the adverse effects of the environment. They also synthetize defence compounds, including stress proteins – dehydrins. Production of dehydrins occurs in connection with drought, low temperatures, frost or high salinity of the soil, i.e. with phenomena that directly or indirectly cause water stress to the plant. Simply put – dehydrins protect plant cells from the effects of dehydration in difficult times.
Dehydrin research is a common practice for economically important agricultural crops; for forest trees however, it is still a rather marginal issue. Researchers from the Department of Genetics and Physiology of Forest Trees of the Faculty of Forestry and Wood Sciences set out to investigate these proteins in spruce. Norway spruce (Picea abies) is a great example of a species that is evolutionarily well adapted to the conditions in which it lives. Although it is known for its susceptibility to drought, spruce has effectively adapted to the environment by creating three so-called ecotypes. Ecotypes are groups of populations within a species that share a similar set of morphological and genetic traits and adaptations. They arise depending on the ecological conditions of the habitat and the altitude. At first glance they differ mainly in the shape of the crown. It is the low-elevation form, whose individuals grow up to 500 m above sea level, the high-elevation form, growing above the border of 1100 m above sea level, and the medium-elevation form, which fills the areas between them.
The aim of the research was to evaluate whether the spruce ecotypes differ in their ability to cope with drought through the production of dehydrins. This was evaluated during fifteen months on the field trial that corresponded to a Norway spruce clone bank, established in 1970s, where all ecotypes were present. It is remarkable that although all individuals were exposed to the same environmental conditions of the stand, they retained the characteristics of their ecotype. And what about the dehydrins? Some groups of dehydrins were produced by all ecotypes without distinction. Individuals were probably able to adapt to the new environment and therefore increased production of some stress proteins was not necessary. Another group of dehydrins manifested itself equally in the low- and medium-elevation ecotype, but differed significantly in the high-elevation one. Such a difference could be explained by the fact that the production of this group of dehydrins is less influenced by the environment and is rather coded genetically, i.e. by affiliation with a given ecotype.
At present, however, climate change shuffles cards of the evolution. It leads to a simple but fundamental conclusion of the research – not every spruce is the same. We don't have to go far for the consequences of this statement. The existing coping mechanisms and local adaptation are no longer sufficient for spruce which causes, among others, the unprecedented spread of the bark beetle, which attacks drought-weakened trees. Nevertheless, the knowledge of the invisible chemical weapons of the spruce takes us one step closer to understanding this coniferous tree and shows us how to protect it efficiently in difficult times.
RNDr. Jaroslav Čepl, Ph.D.
Jaroslav Čepl graduated from evolutionary biology at the Faculty of Science of the Charles University. At present, he works at the Department of Genetics and Physiology of Forest Trees, where he is engaged both in pedagogical and research activities. His research is currently focused on the use of physiological parameters in forest tree breeding. In 2017, he received the award of the Minister of Agriculture for his publication Genetic variability and heritability of chlorophyll a fluorescence parameters in Scots pine (Pinus sylvestris L.).
Prepared by: Dagmar Zádrapová