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Steven H. Strauss - One of the best experts on this subject based on the ideXlab platform.
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Opportunities for Innovation in Genetic Transformation of Forest Trees
Frontiers in Plant Science, 2018Co-Authors: Michael Nagle, Annabelle Dejardin, Gilles Pilate, Steven H. StraussAbstract:The incorporation of DNA into plant genomes followed by regeneration of non-chimeric stable plants (transformation) remains a major challenge for most plant species. Forest Trees are particularly difficult as a result of their biochemistry, aging, desire for clonal fidelity, delayed reproduction, and high diversity. We review two complementary approaches to transformation that appear to hold promise for Forest Trees.
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Forestry's fertile crescent: the application of biotechnology to Forest Trees.
Plant biotechnology journal, 2003Co-Authors: Malcolm M. Campbell, Amy M. Brunner, Helen M. Jones, Steven H. StraussAbstract:Summary Relative to crop plants, the domestication of Forest Trees is still in its infancy. For example, the domestication of many crop plants was initiated some 10 000 years ago in the so-called ‘Fertile Crescent’ of the Middle East. By contrast, the domestication of Forest Trees for the purposes of producing more fibre began in earnest in the last half century. The application of biotechnology to Forest Trees offers a great potential to hasten the pace of tree improvement for desirable end uses. This review outlines some of the progress that has been made in the application of biotechnology to Forest Trees, and considers the prospects for biotechnologically based tree improvement in the future.
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Genetic engineering of reproductive sterility in Forest Trees
Molecular Breeding, 1995Co-Authors: Steven H. Strauss, Amy M. Brunner, William H. Rottmann, Lorraine A. SheppardAbstract:Containment of transgenes inserted into genetically engineered Forest Trees will probably be necessary before most commercial uses are possible. This is a consequence of (1) high rates of gene dispersal by pollen and seed, (2) proximity of engineered Trees in plantations to natural or feral stands of interfertile species, and (3) potentially undesirable ecological effects if certain transgenes become widely dispersed. In addition to gene containment, engineering of complete or male sterility may stimulate faster wood production, reduce production of allergenic pollen, and facilitate hybrid breeding. We review the regulatory and ecological rationale for engineering sterility, potentially useful floral genes, strategies for creating sterility-causing transgenes, and problems peculiar to engineering sterility in Forest Trees. Each of the two primary options — ablating floral tissues via floral promoter-cytotoxin fusions, and disrupting expression of essential floral genes by various methods of gene suppression — has advantages and disadvantages. Because promoters from structural and enzymatic floral-specific genes often work well in heterologous species, ablation methods based on these genes probably will not require cloning of homologs from angiosperm Trees. Methods that inhibit gene expression will require cloning of tree genes and may be more prone to epigenetic variability, but should allow assay of transgene efficacy in seedlings. Practical constraints include the requirement for vegetative propagation if complete sterility is engineered and the need for highly stable forms of sterility in long-lived Trees. The latter may require suppression of more than one floral gene or employment of more than one genetic mechanism for sterility.
Antoine Kremer - One of the best experts on this subject based on the ideXlab platform.
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long distance gene flow and adaptation of Forest Trees to rapid climate change
Ecology Letters, 2012Co-Authors: Antoine Kremer, Ophélie Ronce, Frédéric Guillaume, Gil Bohrer, Ran Nathan, Jon R. Bridle, Richard Gomulkiewicz, J J Robledoarnuncio, Etienne K. KleinAbstract:Forest Trees are the dominant species in many parts of the world and predicting how they might respond to climate change is a vital global concern. Trees are capable of long-distance gene flow, which can promote adaptive evolution in novel environments by increasing genetic variation for fitness. It is unclear, however, if this can compensate for maladaptive effects of gene flow and for the long-generation times of Trees. We critically review data on the extent of long-distance gene flow and summarise theory that allows us to predict evolutionary responses of Trees to climate change. Estimates of long-distance gene flow based both on direct observations and on genetic methods provide evidence that genes can move over spatial scales larger than habitat shifts predicted under climate change within one generation. Both theoretical and empirical data suggest that the positive effects of gene flow on adaptation may dominate in many instances. The balance of positive to negative consequences of gene flow may, however, differ for leading edge, core and rear sections of Forest distributions. We propose future experimental and theoretical research that would better integrate dispersal biology with evolutionary quantitative genetics and improve predictions of tree responses to climate change.
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Long distance gene flow and adaptation of Forest Trees to rapid climate change
Ecology Letters, 2012Co-Authors: Antoine Kremer, Ophélie Ronce, Juan J. Robledo- Arnuncio, Frédéric Guillaume, Gil Bohrer, Ran Nathan, Jon R. Bridle, Richard Gomulkiewicz, Etienne K. Klein, Kermit RitlandAbstract:Long distance gene flow and adaptation of Forest Trees to rapid climate change
Kristen Frole - One of the best experts on this subject based on the ideXlab platform.
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leaf structural diversity is related to hydraulic capacity in tropical rain Forest Trees
Ecology, 2006Co-Authors: Lawren Sack, Kristen FroleAbstract:The hydraulic resistance of the leaf (Rl) is a major bottleneck in the whole plant water transport pathway and may thus be linked with the enormous variation in leaf structure and function among tropical rain Forest Trees. A previous study found that Rl varied by an order of magnitude across 10 tree species of Panamanian tropical lowland rain Forest. Here, correlations were tested between Rl and 24 traits relating to leaf venation and mesophyll structure, and to gross leaf form. Across species, Rl was related to both venation architecture and mesophyll structure. Rl was positively related to the theoretical axial resistivity of the midrib, determined from xylem conduit numbers and dimensions, and Rl was negatively related to venation density in nine of 10 species. Rl was also negatively related to both palisade mesophyll thickness and to the ratio of palisade to spongy mesophyll. By contrast, numerous leaf traits were independent of Rl, including area, shape, thickness, and density, demonstrating that lea...
Christian Korner - One of the best experts on this subject based on the ideXlab platform.
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water savings in mature deciduous Forest Trees under elevated co2
Global Change Biology, 2007Co-Authors: Sebastian Leuzinger, Christian KornerAbstract:Stomatal conductance of plants exposed to elevated CO2 is often reduced. Whether this leads to water savings in tall Forest-Trees under future CO2 concentrations is largely unknown but could have significant implications for climate and hydrology. We used three different sets of measurements (sap flow, soil moisture and canopy temperature) to quantify potential water savings under elevated CO2 in a ca. 35 m tall, ca. 100 years old mixed deciduous Forest. Part of the Forest canopy was exposed to 540 ppm CO2 during daylight hours using free air CO2 enrichment (FACE) and the Swiss Canopy Crane (SCC). Across species and a wide range of weather conditions, sap flow was reduced by 14% in Trees subjected to elevated CO2, yielding ca. 10% reduction in evapotranspiration. This signal is likely to diminish as atmospheric feedback through reduced moistening of the air comes into play at landscape scale. Vapour pressure deficit (VPD)-sap flow response curves show that the CO2 effect is greatest at low VPD, and that sap flow saturation tends to occur at lower VPD in CO2-treated Trees. Matching stomatal response data, the CO2 effect was largely produced by Carpinus and Fagus, with Quercus contributing little. In line with these findings, soil moisture at 10 cm depth decreased at a slower rate under high-CO2 Trees than under control Trees during rainless periods, with a reversal of this trend during prolonged drought when CO2-treated Trees take advantage from initial water savings. High-resolution thermal images taken at different heights above the Forest canopy did detect reduced water loss through altered energy balance only at > 5 m distance (0.44 K leaf warming of CO2-treated Fagus Trees). Short discontinuations of CO2 supply during morning hours had no measurable canopy temperature effects, most likely because the stomatal effects were small compared with the aerodynamic constraints in these dense, broad-leaved canopies. Hence, on a seasonal basis, these data suggest a >10% reduction in water consumption in this type of Forest when the atmosphere reaches 540% ppm CO2.
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carbon flux and growth in mature deciduous Forest Trees exposed to elevated co2
Science, 2005Co-Authors: Christian Korner, Roman Asshoff, Olivier Bignucolo, Stephan Hattenschwiler, Sonja G Keel, Susanna Pelaezriedl, Steeve Pepin, Rolf T W Siegwolf, Gerhard ZotzAbstract:Whether rising atmospheric carbon dioxide (CO 2 ) concentrations will cause Forests to grow faster and store more carbon is an open question. Using free air CO 2 release in combination with a canopy crane, we found an immediate and sustained enhancement of carbon flux through 35-meter-tall temperate Forest Trees when exposed to elevated CO 2 . However, there was no overall stimulation in stem growth and leaf litter production after 4 years. Photosynthetic capacity was not reduced, leaf chemistry changes were minor, and tree species differed in their responses. Although growing vigorously, these Trees did not accrete more biomass carbon in stems in response to elevated CO 2 , thus challenging projections of growth responses derived from tests with smaller Trees.
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non structural carbon compounds in temperate Forest Trees
Plant Cell and Environment, 2003Co-Authors: Gunter Hoch, Andreas Richter, Christian KornerAbstract:The current carbon supply status of temperate Forest Trees was assessed by analysing the seasonal variation of nonstructural carbohydrate (NSC) concentrations in leaves, branch wood and stem sapwood of 10 tree species (six deciduous broad-leafed, one deciduous conifer and three evergreen conifer Trees) in a temperate Forest that is approximately 100 years old. In addition, all woody tissue was analysed for lipids (acylglycerols). The major NSC fractions were starch, sucrose, glucose and fructose, with other carbohydrates (e.g. raffinose and stachyose) and sugar alcohols (cyclitols and sorbitol) playing only a minor quantitative role. The radial distribution of NSC within entire stem cores, assessed here for the first time in a direct interspecific comparison, revealed large differences in the size of the active sapwood fraction among the species, reflecting the specific wood anatomy (ring-porous versus diffuse-porous xylem). The mean minimum NSC concentrations in branch wood during the growing season was 55% of maximum, and even high NSC concentrations were maintained during times of extensive fruit production in masting Fagus sylvestris . The NSC in stem sapwood varied very little throughout the season (cross species mean never below 67% of maximum), and the small reductions observed were not significant for any of the investigated species. Although some species contained substantial quantities of lipids in woody tissues (‘fat Trees’; Tilia , Pinus , Picea , Larix ), the lipid pools did not vary significantly across the growing season in any species. On average, the carbon stores of deciduous Trees would permit to replace the whole leave canopy four times. These data imply that there is not a lot of leeway for a further stimulation of growth by ongoing atmospheric CO 2 enrichment. The classical view that deciduous Trees rely more on C-reserves than evergreen Trees, seems unwarranted or has lost its justification due to the greater than 30% increase in atmospheric CO 2 concentrations over the last 150 years.
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A simple method for testing leaf responses of tall tropical Forest Trees to elevated CO_2
Oecologia, 1996Co-Authors: Christian Korner, Mirjam WürthAbstract:The effects of atmospheric CO_2 enrichment on mature Trees in their natural environment are largely unknown. Here we present a new, and inexpensive technique which can be used in situ to address some key physiological questions related to the CO_2 problem. Small, light-weight cups mounted on the lower side of rigid leaves at the top of tall tropical Forest Trees were supplied with CO_2-enriched air derived from a low-technology air mixing device utilizing Forest floor CO_2 evolution. We present the scientific rationale for such field experiments, technical details, an assessment of potential cup artifacts and first results illustrating effects of elevated CO_2 on stomata and carbohydrate accumulation in the canopies of mature Trees.
Caryn N. Oates - One of the best experts on this subject based on the ideXlab platform.
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The Road to Resistance in Forest Trees.
Frontiers in plant science, 2019Co-Authors: Sanushka Naidoo, Bernard Slippers, Jonathan M. Plett, Donovin Coles, Caryn N. OatesAbstract:In recent years, Forests have been exposed to an unprecedented rise in pests and pathogens. This, coupled with the added challenge of climate change, renders Forest plantation stock vulnerable to attack and severely limits productivity. Genotypes resistant to such biotic challenges are desired in plantation Forestry to reduce losses. Conventional breeding has been a main avenue to obtain resistant genotypes. More recently, genetic engineering has become a viable approach to develop resistance against pests and pathogens in Forest Trees. Tree genomic resources have contributed to advancements in both these approaches. Genome-wide association studies and genomic selection in tree populations have accelerated breeding tools whilst integration of various levels of omics information facilitates the selection of candidate genes for genetic engineering. Furthermore, tree associations with non-pathogenic endophytic and subterranean microbes play a critical role in plant health and may be engineered in Forest Trees to improve resistance in the future. We look at recent studies in Forest Trees describing defence mechanisms using such approaches and propose the way forward to developing superior genotypes with enhanced resistance against biotic stress.