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Großhansdorf, Germany

Luttschwager D.,Leibniz Center for Agricultural Landscape Research | Ewald D.,Thunen Institute of Forest Genetics | Atanet Alia L.,Leibniz Center for Agricultural Landscape Research
Acta Physiologiae Plantarum | Year: 2015

The establishment of short-rotation poplar plantations for the sustainable production of raw material and energy is often limited by low precipitation and poor soil conditions. Breeding research must therefore focus on combining performance with drought tolerance. Eight poplar clones were generated by tissue culture. Three times during seasonal development, photosynthesis and transpiration were measured in fully developed leaves under controlled conditions in a climate chamber. Light response curves were modelled based on these data. The efficiency of water use was analysed for all clones under well-watered conditions, and partly significant differences were observed with regard to intrinsic water use efficiency (WUE). Moreover, at the end of the season, the plants were considerably different in their biometrics, particularly in the shoot–root relationship, which might substantially influence drought resistance. A general ranking of the performance of the clones is difficult because certain physiological parameters turn over during the course of the season. However, certain “strategies” that could be divided into “generalist” and “specialist” stand out for individual clones. The aspen clone Großdubrau 1 (“specialist”) showed the maximum height, the greatest seasonal differences in WUE and the most weakly developed root system. By contrast, the poplar clone Max 2 (“generalist”) had the lowest height increase but a well-developed root system and lower volatility in WUE. Thus, drought tolerance under stress conditions may exhibit a degree of predictability. Therefore, a dry stress experiment is planned to test the two contrasting clones. © 2015, Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.

Schroeder H.,Thunen Institute of Forest Genetics | Fladung M.,Thunen Institute of Forest Genetics
IForest | Year: 2015

About 30 species within the genus Populus are classified in six sections. Several species belonging to different sections are cross-compatible, resulting in a high number of naturally occurring interspecific hybrids. Additionally, an even higher number of hybrids has been produced in huge breeding programs during the last 100 years. Hence, determination of poplar species used for the production of “multi-species-hybrids” is often difficult, and a challenge for the development of molecular markers aimed at species identification. Moreover, 14 of the 30 poplar species known are often used for the production of artificial hybrids and clones. In this study, over 20 regions of the chloroplast genome of poplars were analyzed by the use of 23 primer combinations already established for “barcoding” purposes, and 17 new primer combinations previously designed, with the aim of testing their suitability to differentiate 14 poplar species. Only about half of the established barcoding primer combinations yielded PCR amplification products, while new primer combinations had a much higher amplification success. Species-specific SNPs or Indels were detected in 11 out of the 14 poplar species analyzed. In order to set up a low-cost and fast method for species identification, we developed PCR-RFLPs applicable to seven of the species-specific SNPs. Overall, a high variability was found in the chloroplast intergenic spacers, as much as four primer combinations were needed to differentiate 11 species. Based on our results, the use of multi-locus combinations is recommended in barcoding analyses. © SISEF.

Ahuja M.R.,Thunen Institute of Forest Genetics | Fladung M.,Thunen Institute of Forest Genetics
Tree Genetics and Genomes | Year: 2014

Transgene integration and inheritance have been investigated in a number of crop plants and few tree species. Transgene integration is predominantly a random process, whether mediated by Agrobacterium or particle bombardment. Depending on the genomic position of the integrated transgene and structure of the integration site as well as copy number of the transgene in the genome, its expression may be stable or variable. Therefore, integration patterns would affect the mode of transgene inheritance in plants, regardless of the method of gene transfer. So far, both Mendelian and non-Mendelian inheritance of transgenes has been reported across several generations (T1-T3) of crop plants. In few tree species (apple, poplar, plum, and American chestnut), mostly Mendelian inheritance of the transgenes has been observed in the T1 or BC1 generations. However, detailed studies in the transgenic papaya trees showed Mendelian segregation of the transgene in the T1 generation but non-Mendelian inheritance in the T2 generation. Variation in transgene inheritance was also detected in transgenic apple and plum trees. Long generation cycles in many economically important tree species preclude investigation of inheritance of transgenes in the tree progeny. Production of early flowering trees, either by genetic modification or by environmental modulation, would facilitate the study of transgene inheritance across generations of transgenic trees. In order to overcome problems of randomness of transgene integration, targeted transgene insertions by homologous or site-specific recombination or by designer recombinases or nucleases offer prospects for stable integration of transgenes in predetermined locations in the plant genome. And perhaps, that might provide a platform for stable expression and Mendelian inheritance of transgenes in plants. © 2014 Springer-Verlag Berlin Heidelberg.

Blanc-Jolivet C.,Thunen Institute of Forest Genetics | Degen B.,Thunen Institute of Forest Genetics
Tree Genetics and Genomes | Year: 2014

Conservation of forest genetic resources has drawn much attention in the last decades, as it prevents negative effects of genetic erosion on adaptability potential of material used for afforestation. According to the German Act on Forest Reproductive Material, seed harvesting must occur in certified stands. Seed lots must stem from a minimum number of seed-trees, although the effect of this limit on genetic diversity has not been addressed. In this study, we aimed at understanding the effect of seed harvesting strategies on genetic diversity. We used the simulation model Eco-Gene and real molecular data to disentangle the effects of number of seed-trees and harvesting method in three wild cherry (Prunus avium) stands. Our results outline the importance of harvesting genetically different or distant seed-trees in maintaining genetic diversity. Besides optimal sampling strategy, we also recommend minimum harvesting of 25 seed-trees to reach 90 % of genetic diversity available within the stand. The outcomes of these results for the practice are also discussed. © 2014 Springer-Verlag Berlin Heidelberg.

Ewald D.,Thunen Institute of Forest Genetics | Naujoks G.,Thunen Institute of Forest Genetics
Dendrobiology | Year: 2015

Over the last 15 years, shoot material from wavy grain sycamore maples (Acer pseudoplatanus L.) was collected from crowns of trees which were harvested and the stems then sold for very high values. Starting with grafts from this material, cutting propagation was tested and a tissue culture method was elaborated. However, the question of whether the wavy grain structure is expressed after vegetative propagation still remained unsolved. Recently, one of the oldest cuttings (11 years) and two grafts (17 years) were cut to look for structures of wavy grain expression. Veneer was produced from the log of the cutting- derived tree. Staining experiments were carried out using veneer sheets to improve the appearance of the structures. Based on these experiments, and in using morphological comparisons with veneer from adult wavy grain sycamore, we present the first evidence for the appearance of undulating fibre structures and the beginnings of wavy grain formation even in material at around ten years of age. A hypothesis related to the formation of wavy grain in deciduous trees is discussed. © 2015, Polska Akademia Nauk. All rights reserved.

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