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International audience; Complete Populus genome sequences are available for the nucleus (P. trichocarpa; section Tacamahaca) and for chloroplasts (seven species), but not for mitochondria. Here, we provide the complete genome sequences of the chloroplast and the mitochondrion for the clones P. tremula W52 and P. tremula x P. alba 717-1B4 (section Populus). The organization of the chloroplast genomes of both Populus clones is described. A phylogenetic tree constructed from all available complete chloroplast DNA sequences of Populus was not congruent with the assignment of the related species to different Populus sections. In total, 3,024 variable nucleotide positions were identified among all compared Populus chloroplast DNA sequences. The 5-prime part of the LSC from trnH to atpA showed the highest frequency of variations. The variable positions included 163 positions with SNPs allowing for differentiating the two clones with P. tremula chloroplast genomes (W52, 717-1B4) from the other seven Populus individuals. These potential P. tremula-specific SNPs were displayed as a whole-plastome barcode on the P. tremula W52 chloroplast DNA sequence. Three of these SNPs and one InDel in the trnH-psbA linker were successfully validated by Sanger sequencing in an extended set of Populus individuals. The complete mitochondrial genome sequence of P. tremula is the first in the family of Salicaceae. The mitochondrial genomes of the two clones are 783,442 bp (W52) and 783,513 bp (717-1B4) in size, structurally very similar and organized as single circles. DNA sequence regions with high similarity to the W52 chloroplast sequence account for about 2% of the W52 mitochondrial genome. The mean SNP frequency was found to be nearly six fold higher in the chloroplast than in the mitochondrial genome when comparing 717-1B4 with W52. The availability of the genomic information of all three DNA-containing cell organelles will allow a holistic approach in poplar molecular breeding in the future.

This book provides up-to-date information on the environmental impact of transgenic trees on genetically modified tree (GMT) communication strategy. It is useful to public/private organisations as well as to private and public research bodies and universities worldwide since it reports on the global status of GMT research and policy. A high number of genetically modified trees (GMTs) with altered or novel characteristics have been produced in the last 15 years. However, their very low public acceptance is a basic problem in their commercialization. Breeders anticipate economic and ecological benefits, like reduced product costs and less pressure on native forests, while opponents fear risks, such as unintended spread of GMTs. But what is true? To answer this question, the COST Action FP0905 focused on key aspects related to GMTs: (a) biological characterization; (b) assessment of possible environmental impacts; (c) socio-economic implications and public acceptance/concerns; (d) providing science-based information to communicate with the public.

International audience

Problems, such as the impact on biodiversity and the potential escapes of the trans-genes into wild populations can be amplified in the case of long-lived forest species. Therefore, studies of possible environmental impacts of transgenic forest plants (poplar) in the forest environment are important. Few studies have been published considering the alteration of the transgenic host plant genome for the possibility that transgenes can also cause pleiotropic, often undesirable alterations in plant metabolism and physiology. Other studies carried out so far, concerned the use of transgenesis to obtain poplar mutants for genomic studies or poplar breeding just for an economic purpose. The screening of the transgenic plants carrying the cry gene is in course, and the evaluation of the copy number as well as expression of the inserted gene is under evaluation. The final aim is to unravel possible pleiotropic metabolic effects in the transgenic trees following cry gene expression in P. alba and P. tremula x P. tremuloides transgenic lines.

The problems related to global changes, mainly caused by human activities, are the origin of much concern for the health of the environment. Oil and carbon combustion, the use of chlorofluorocarbons, and deforestation are some of the principal factors responsible for CO2 production and for air temperature increase. The scenario is factors leading to global changes affecting precipitation patterns, nitrogen concentration in the atmosphere, UV-B radiation increaseand temperature increase. Forest trees constitute a relevant economic and ecological resource that is under severe treat by environmental changes. The principal aim is to investigate the response to CO2 from three different genotypes of Fagus sylvatica by gene expression and ecophysiological analyses. Shoots of F. sylvatica (Montieri (GR), Italy) and F. sylvatica "purpurea tree" were grafted on F. sylvatica rootstocks. Plants were grown under controlled conditions in a climate chamber using the same temperature and light parameters, while CO2 concentrations were approx. 380-400 ppm (ambient) in the control room and 1000 ppm (high) in the experimental room. A PAM fluorescence system (PAM-2000, Heinz Walz GmbH, Effeltrich, Germany) with a 6 mm diameter standard fibre optic was used for the measurements of the in vivo photosynthesis. Under ambient conditions photosynthesis (expressed as electron transport rate) was higher in the Italian compared to the German genotype. After 4 d under high CO2 treatment, electron transport rate showed increased values compared to the plants growing under ambient CO2. Photosynthesis of plants (Italy) adapted to high CO2 decreased immediately after been exposed for 2 h to ambient CO2. No down-regulation of photosynthesis could be observed in leaves at high CO2 level. Microarrays analyses have already been done and preliminary results will be discussed.

Gene expression and ecophysiology analyses of different Fagus sylvatica genotypes under high level of CO2

Preliminary results of different cry transgenic poplar lines.

Problems, such as the impact on biodiversity and the potential escapes of the trans-genes into wild populations can be amplified in the case of long-lived forest species. Thus, studies of possible environmental impacts of transgenic forest plants (poplar) in the forest environment are important. Although a number of studies have been carried out so far considering the use of transgenesis for genomic studies, only little is known about biosafety issues of transgenic trees foreseen for breeding purposes. As a model transgenic tree system, we have produced Populus alba and P. tremula transgenic lines carrying the cry gene from Bacillus thuringiensis. These transgenic are under screening to unravel possible pleiotropic metabolic effects in the transgenic trees following cry gene expression. It is also not known how the use of cry-transgenic poplars affects composition and activities of soil microbial communities which affect soil health. In addition to foreign DNA, proteins from crytransgenic poplars can be released into the soil via plant residues and their persistence can constitute not only a selective pressure towards the target organisms, but also a possible threat for non-target ones with unpredictable consequences on the food chain sustained by these organisms. The work is carried out on an integrated and multidisciplinary approach (physiology, soil microbiology and biochemistry, genomic, proteomic, and microscopy), involving different scientific groups with different and specific expertise, to assess the mentioned biosafety issues important for forest trees. The screening of the transgenic plants is in course, and the evaluation of the number copy of the inserted gene as well as expression of the inserted gene is under evaluation.

Risks analyses in cry transgenic popla

The problems related to global changes mainly caused by human activities, are the origin of much concern for the health of the environment. Oil and carbon combustion, the use of chlorofluorocarbons, and deforestation are some of the principal factors responsible for enhanced CO2 production, as well as for air temperature increases. This scenario could determine global changes affecting precipitation patterns, nitrogen concentration in the atmosphere, UV radiation increase, and temperature range. Forest trees constitute a relevant economic and ecological resource that is under severe treat by environmental changes. The principal aim is to investigate the response to CO2 from two different F. sylvatica genotypes by gene expression and ecophysiology analyses. Scions of Fagus sylvatica (Montieri (GR), Italy) and F. sylvatica "purpurea tree" (Grosshansdorf, Germany) were grafted on F. sylvatica rootstocks. Plants were grown under controlled conditions in climate chambers. Air temperature was 25°C during light period and 20°C at night, and humidity 60%. Fluorescent lamps (18 36W) provided a photosynthetic active photon flux density (PPFD) of 250 ?mol m-2 s-1 at plant top level. CO2 concentrations were about 450 ppm (ambient) and 1000 ppm (high) for control and high CO2 chamber, respectively. A PAM fluorescence system (PAM-2000, Heinz Walz GmbH, Effeltrich, Germany) with a 6 mm diameter standard fibre optic was used for the measurements of the in vivo photosynthesis. Light response curves were recorded up to a light intensity of 420 ?mol m-2 s-1. At each step the leaf was illumined for 3 minutes. Under ambient CO2 concentrations, electron transport rate (ETR) was higher in the Italian compared to the German genotype. After 4 days at high CO2 level, the ETR increased compared to plants growing in the control chamber. Photosynthesis of Italian genotype adapted to 1000 ppm of CO2 decreased immediately after been exposed for 2 hours to 450 ppm CO2. No down-regulation of photosynthesis could be observed in leaves at 1000 ppm CO2 level. Microarray analyses are in course and preliminary results will be discussed.