KLIFF - Climate impact and adaptation research in Lower Saxony (Klimafolgenforschung in Nierdersachsen)
Duration of the project: 2009 - 2013
Contact: Prof. Dr. Andrea Polle, Email: apolle(at)gwdg.de
Current climate projections for Lower Saxony predict increasing air temperatures and a rise in the frequency and duration of summer droughts. European beech (Fagus sylvatica L.) is the most important tree species of the potential natural vegetation in Lower Saxony. It is unknown whether beech trees under the growth conditions of Lower Saxony are negatively affected by climate.
The main goal of subproject P4 "Molecular and physiological adaptation and acclimation to drought" was to investigate how European beech responds to drought at the cellular level and how this translates into the performance of this important species under dry conditions. This subproject, thereby, contributes to the central aims of the KLIFF project (www.kliff-niedersachsen.de). In particular, we studied the responses of European beech to drought stress in three locations of Lower Saxony differing in annual precipitation (500-800 mm year-1), using both field and experimental approaches.
Our objectives were to answer the following questions:
- Which genes are affected by drought stress and what is their relation to wood formation?
- What role do phenotype and genetic variability play within the beech's response to drought stress?
It is known that changes in wood (e.g. the reduction of vessel diameter within the xylem) are very important for the adaption to drought stress. Only little is known about the molecular basis of this adaptation mechanism. We conducted field experiments with beech trees grown on two soil types (loam and sand) in three sites along precipitation gradient: Unterlüss 800 mm, Göhrde 630 mm, Calvörde 550 mm. Wood sampling was carried out during the project in April, June, August and October. The samples were analysed for the expression of genes involved in drought stress adaptation, e.g. regarding the stress hormone abscisic acid. Furthermore, in cooperation with the department for plant biochemistry at the University of Goettingen (AG Feussner), we determined phytohormones in the developing wood. The sites differed severely across the seasons. Using RNA sequencing and multivariate data analyses, groups of genes affecting wood formation under stress were identified. These genes might be further developed as a marker for forest genetic analysis.
We used beech saplings collected along a moisture gradient to investigate whether gene expression indicated preformed adaptation phenomena to drought. Sampling was conducted in cooperation with AG Leuschner and AG Finkeldey. The results showed that saplings from humid locations showed a strong response in their gene expression to drought stress, whereas saplings from dry sites showed only little reaction under the same conditions. This difference in gene regulation reinforces that genetic adaption already takes place (Carsjens et al. 2014). The selected genes are therefore important candidates for the beech's adaption to drought stress. It is advisable to involve those candidate genes in further forest genetic analysis as we could show a correlation between drought tolerance and gene expression.
Carsjens C, Nguyen NQ, Guzy J, Knutzen F, Meier IC, Müller M, Finkeldey R, Leuschner C, Polle A (2014) Intra-specific variations in expression of stress-related genes in beech progenies are stronger than drought-induced responses. Tree Physiology 34(12): 1348-1361, doi: 10.1093/treephys/tpu093
Polle A, Janz D, Teichmann T, Lipka V (2013) Poplar genetic engineering: promoting desirable wood characteristics and pest resistance. Applied Microbiology and Biotechnology 97(13): 5669-5679, doi: 10.1007/s00253-013-4940-8.
Beniwal RS, Hooda MS, Polle A. (2011) Amelioration of planting stress by soil amendment with a hydrogel-mycorrhiza mixture for early establishment of beech (Fagus syvatica L.) seedlings. Annals of Forest Science 68(4): 803-810, doi: 10.1007/s13595-011-0077-z
Nguyen Ngoc Q (2016) Anatomical, physiological and molecular responses of European beech (Fagus sylvatica L.) to drought. PhD Dissertation, Georg-August-University Göttingen.
Rattay JC (2012) Anatomie der Holzbildung in einem Trockenstressgradienten. Bachelor Thesis, Georg-August-University Göttingen.
Guzy J (2013) Genexpression der Buche unter Trockenstress. Bachelor Thesis, Georg-August-University Göttingen.
Nguyen Ngoc Q, Carsjens C, Lohaus G, Janz D, Iven T, Feussner I, Polle A (2015) Wood formation in the real world. 35th New Phytologist symposium. The genomes of forest trees: New Frontier of Forest Biology-Arnold Arboretum of Harvard University, Boston, MA, USA (16-17 June 2015)
Nguyen Ngoc Q, Carsjens C, Janz D, Lohaus G, Polle A (2013) European beech (Fagus sylvatica L.) along a precipitation gradient: effects on anatomical, physiological and molecular features of wood. KLIFF conference - Climate impact and adaption research in Lower Saxony, Göttingen, Germany (1-2 Sep 2013)
Polle A (2010) Physiological and molecular adaptation of trees to drought. KLIFF Int. Workshop "Adaptation of perennial plants to episodic drought: impact on ecosystem", Göttingen, Germany (6-8 Oct 2010)
Pena R (2010) Ectomycorrhizas of beech - functional diversity for nitrogen uptake under drought; effect of a direct competitor (Cornus sp.). KLIFF Int. Workshop "Adaptation of perennial plants to episodic drought: impact on ecosystem", Göttingen, Germany (6-8 Oct 2010)
Polle A (2010) The transcriptome of cell wall changes under stress. 4th Joint New Zealand - German Symposium on Plant Cell Walls, Hamburg, Germany (12 Oct 2010)
Polle A (2010) Elevated atmospheric CO2: friend or foe for biological wood production? First Summer School - C1-Chemistry for resource and energy management, Hamburg, Germany (21 July 2010)
Ministry for Science and Culture of Lower Saxony (Germany) funded the program "Klimafolgenforschung in Niedersachsen" (KLIFF). Ngoc Quynh Nguyen was funded by a PhD scholarship awarded by the Ministry of Education and Training of Viet Nam.