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William A Powell - One of the best experts on this subject based on the ideXlab platform.
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chestnut american Castanea dentata marsh borkh
Methods of Molecular Biology, 2015Co-Authors: Charles A Maynard, Linda D Mcguigan, Allison D Oakes, Bo Zhang, Andrew E Newhouse, Lilibeth C Northern, Allison M Chartrand, Logan R Will, Kathleen M Baier, William A PowellAbstract:: The key to successful transformation of American chestnut is having the correct combination of explant tissue, selectable markers, a very robust DNA delivery system, and a reliable regeneration system. The most important components of this transformation protocol for American chestnut are the following: starting out with rapidly dividing somatic embryos, treating the embryos gently throughout the Agrobacterium inoculation and cocultivation steps, doing the cocultivation step in desiccation plates, and finally transferring the embryos into temporary-immersion bioreactors for selection. None of these departures from standard Agrobacterium transformation protocols is sufficient by itself to achieve transgenic American chestnut, but each component makes a difference, resulting in a highly robust protocol. The average transformation efficiency that can be expected using the described protocol is approximately 170 stable embryogenic transformation events per gram of somatic embryo tissue, a considerable improvement over the 20 transformation events per gram we reported in 2006 (Maynard et al. American chestnut (Castanea dentata (Marsh.) Borkh.) Agrobacterium protocols, 2nd ed., 2006). We have regenerated nearly 100 of these events, containing 23 different gene constructs, into whole plants. As of the fall of 2013, we had a total of 1,275 transgenic chestnut trees planted at eight locations in New York State and one in Virginia. Based on a combination of field-trial inoculations, greenhouse small-stem inoculations, and detached-leaf assays, we have identified three transgenes that produce stronger resistance to chestnut blight than non-transgenic American chestnut. Depending on the transgene and the event, this resistance can be either intermediate between American chestnut and Chinese chestnut, approximately equal to or even higher than the resistance naturally found in Chinese chestnut.
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Application of airlift bioreactors to accelerate genetic transformation in American chestnut
Plant Cell Tissue and Organ Culture (PCTOC), 2014Co-Authors: Lisheng Kong, William A Powell, Campbell J Nairn, Kathleen Baier, Christine T. Holtz, Haley Houke, Scott A MerkleAbstract:Airlift bioreactors (ALBs) were constructed and tested for their potential to enhance chestnut embryogenic tissue proliferation for genetic transformation and mass propagation. Multiple genotypes of American chestnut ( Castanea dentata ) and backcross hybrids of American chestnut and Chinese chestnut ( C. dentata × Castanea mollissima ) were cultured in ALBs. Medium for tissue proliferation in ALBs was woody plant medium supplemented with 3 g l^−1 sucrose, 0.5 g l^−1 l -glutamine and 2 mg l^−1 2,4-dichlorophenoxyacetic acid. Optimum culture conditions for 1-l ALBs included 2 % (w/v) tissue inoculation density for culture initiation, 200 ml min^−1 airflow rate, and weekly feeding with fresh medium (80–85 %, v/v). Compared with flasks, ALBs generated higher yields of tissue mass and larger fractions of small cell clumps (
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a threshold level of oxalate oxidase transgene expression reduces cryphonectria parasitica induced necrosis in a transgenic american chestnut Castanea dentata leaf bioassay
Transgenic Research, 2013Co-Authors: Bo Zhang, Charles A Maynard, Allison D Oakes, Andrew E Newhouse, Kathleen M Baier, William A PowellAbstract:American chestnut (Castanea dentata) was transformed with a wheat oxalate oxidase (oxo) gene in an effort to degrade the oxalic acid (OA) secreted by the fungus Cryphonectria parasitica, thus decreasing its virulence. Expression of OxO was examined under two promoters: a strong constitutive promoter, CaMV 35S, and a predominantly vascular promoter, VspB. Oxo gene transcription was quantified by RT-qPCR. Relative expression of OxO varied approximately 200 fold among events produced with the 35S-OxO. The lowest 35S-OxO event expressed approximately 3,000 fold higher than the highest VspB-OxO event. This was potentially due to the tissue-specific nature of the VspB-controlled expression, the strength of the CaMV 35S constitutive promoter, or position effects. Leaf assays measuring necrotic lesion length were conducted to better understand the relationship between OxO expression level and the blight fungus in planta. A threshold response was observed between the OxO expression level and the C. parasitica lesion length. Five events of the 35S-OxO line showed significantly reduced lesion length compared to the blight-susceptible American chestnut. More importantly, the lesion length in these five events was reduced to the same level as the blight-resistant Chinese chestnut, C. mollissima. This is the first report on enhanced pathogen resistance in transgenic American chestnut.
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Chestnut resistance to the blight disease: insights from transcriptome analysis
BMC Plant Biology, 2012Co-Authors: Abdelali Barakat, Fred Hebard, Kathleen Baier, Meg E Staton, Chun-huai Cheng, Joseph Park, Norzawani Buang M. Yassin, Stephen P. Ficklin, William A PowellAbstract:Background A century ago, Chestnut Blight Disease (CBD) devastated the American chestnut. Backcross breeding has been underway to introgress resistance from Chinese chestnut into surviving American chestnut genotypes. Development of genomic resources for the family Fagaceae, has focused in this project on Castanea mollissima Blume (Chinese chestnut) and Castanea dentata (Marsh.) Borkh (American chestnut) to aid in the backcross breeding effort and in the eventual identification of blight resistance genes through genomic sequencing and map based cloning. A previous study reported partial characterization of the transcriptomes from these two species. Here, further analyses of a larger dataset and assemblies including both 454 and capillary sequences were performed and defense related genes with differential transcript abundance (GDTA) in canker versus healthy stem tissues were identified.
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assessing ectomycorrhizal associations and transgene expression in transgenic Castanea dentata
BMC Proceedings, 2011Co-Authors: Katherine M Damico, Charles A Maynard, Thomas R Horton, William A PowellAbstract:Background American chestnut (Castanea dentata) once dominated the forests of the eastern United States until the introduction of a Chinese fungal pathogen Cryphonectria parasitica(causal agent of the chestnut blight) decimated the species. This tree was important not only ecologically, but also played a significant role economically. Restoration programs are implementing a variety of techniques, including genetic transformation, to develop a blight resistant tree that can be reintroduced into the native chestnut range (S.A. Merkle, 2007, Tree Genetics and Genomics, 3, 111-18). Specific genes involved in plant defense responses are being introduced into American chestnut via Agrobacterium-mediated transformation, with the hope that one gene or a combination of genes will aid in chestnut defense against blight (L.D. Polin, 2006, Plant Cell, Tissue, and Organ Culture, 84, 69-79). One gene of particular interest to the transgenic project is oxalate oxidase, a defense related gene from wheat that has also been shown to enhance the defense response of other plants when introduced through genetic transformation (H. Liang, 2001, Plant Molecular Biology, 45, 619-29). American chestnut transformation with a binary vector containing oxalate oxidase has produced a number of transgenic events, many of which have already been regenerated plants (unpublished data). Before releasing any transgenic plant it is necessary to assess any non-target impacts the introduced genes may have on associated microbial communities. C. parasiticais a fungal pathogen, so we are particularly interested in studying the effects of any transgene on the symbiotic relationship between the host plant and mycorrhizaeforming fungi. Prior studies have examined the potential impact of transgenic plants on ectomycorrhizal fungi (K. L. Oliver, 2008, Applied and Environmental Microbiology, 74, 5340-48).
Douglass F Jacobs - One of the best experts on this subject based on the ideXlab platform.
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the photosynthetic response of northern red oak quercus rubra l and american chestnut Castanea dentata marsh borkh under varying light intensity and weed competition
2015Co-Authors: Pedro Vitor P Pereira, Jennifer M Lesko, Douglass F JacobsAbstract:Although widely distributed across Indiana and the United States Midwest, conifer plantations consist largely of non-native species that are of no value to the state’s forest products industry. This project’s goal is to develop science-based protocols and specific silvicultural prescriptions for successfully converting conifer plantations to higher value native hardwoods. Quantifying photosynthesis rate in a plant is an important tool to help us discern the best methods for implementing conifer conversion. Seedlings from two different native species, northern red oak (Quercus rubra L.) and American chestnut (Castanea dentata (Marsh.) Borkh), were distributed among three different silvicultural cutting treatments (control, thinning and clear cut). Inside each one, two distinct categories of herbaceous control treatments (weed control and no weed control) were installed. Using an AccuPAR LP-80 sensor, canopy PAR (photosynthetically active radiation) interception was measured. Photosynthetic capacity was assessed with a LICOR 6400-XT analyzer to evaluate efficiency in resource use (water, light, gas exchange) and productivity. Among the treatments, clear cut presented maximum PAR intensity, followed by thinning and control, respectively. Both American chestnut and northern red oak seedlings demonstrated the highest photosynthesis rate (Amax) under high light conditions (clear cut), though photosynthesis of chestnut was greater than that of northern red oak. No significant differences were found between species in the weeding treatment for photosynthesis. Results of this study will provide valuable silvicultural prescriptions to Non-Industrial Private Forest (NIPF) landowners, forestry professionals, as well as state and federal agencies in Indiana and other Midwestern states.
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leaf physiology and biomass allocation of backcross hybrid american chestnut Castanea dentata seedlings in response to light and water availability
Tree Physiology, 2014Co-Authors: Caleb E Brown, Michael V Mickelbart, Douglass F JacobsAbstract:Partial canopy cover promotes regeneration of many temperate forest trees, but the consequences of shading on seedling drought resistance are unclear. Reintroduction of blight-resistant American chestnut (Castanea dentata (Marsh.) Borkh.) into eastern North American forests will often occur on water-limited sites and under partial canopy cover. We measured leaf predawn water potential (Ψpd), leaf gas exchange, and growth and biomass allocation of backcross hybrid American chestnut seedlings from three orchard sources grown under different light intensities (76, 26 and 8% full photosynthetically active radiation (PAR)) and subjected to well-watered or mid-season water-stressed conditions. Seedlings in the water-stress treatment were returned to well-watered conditions after wilting to examine recovery. Seedlings growing under medium- and high-light conditions wilted at lower leaf Ψpd than low-light seedlings. Recovery of net photosynthesis (Anet) and stomatal conductance (gs) was greater in low and medium light than in high light. Seed source did not affect the response to water stress or light level in most cases. Between 26 and 8% full PAR, light became limiting to the extent that the effects of water stress had no impact on some growth and morphological traits. We conclude that positive and negative aspects of shading on seedling drought tolerance and recovery are not mutually exclusive. Partial shade may help American chestnut tolerate drought during early establishment through effects on physiological conditioning.
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Exploration of a rare population of Chinese chestnut in North America: stand dynamics, health and genetic relationships.
Aob Plants, 2014Co-Authors: Amy C. Miller, Keith Woeste, Sandra L. Anagnostakis, Douglass F JacobsAbstract:With the transport of plants around the globe, exotic species can readily spread disease to their native relatives; however, they can also provide genetic resistance to those relatives through hybrid breeding programmes. American chestnut (Castanea dentata) was an abundant tree species in North America until its decimation by intro- duced chestnut blight. To restore chestnut in North America, efforts are ongoing to test putative blight-resistant hy- brids of Castanea dentata and Chinese chestnut (Castanea mollissima), but little is known about the ecology of C. mollissima. In a forest in northeastern USA in which C. mollissima has become established, we explored questions of stand dynamics, health and genetic relationships ofC. mollissimaoffspring to an adjacent parent orchard.We found that C. mollissima was adapted and randomly distributed among native species in this relatively young forest. The gen- etics of the C. mollissimapopulation compared with its parents indicated little effect of selection pressure as each of the parent trees contributedat least one offspring. The easewith which this exoticspecies proliferated callstoquestionwhy C.mollissimaisrareelsewhereinforestsofNorthAmerica.Itislikelythatatimewindowoflowanimalpredationallowed seedlings to establish, and the shallow soil at this site limited the maximum forest canopy height, permitting the char- acteristicallyshort-staturedC. mollissimato avoid suppression. Our results indicate that because C. mollissima exhibited pioneerspeciescharacteristics,hybridsbetweenC.mollissimaandC.dentatahavethepotentialtobesuccessfulpioneer species of future forests in North America, and we challenge the paradigm that exotic tree species are wholly detrimen- taltonativebiodiversity.Wecontendthatexotictreespeciesshouldbeassessednotonlybytheirlevelofthreattonative species, but also by their potential positive impacts on ecosystems via hybrid breeding programmes.
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decomposition rates of american chestnut Castanea dentata wood and implications for coarse woody debris pools
Canadian Journal of Forest Research, 2014Co-Authors: Harmony J Dalgleish, Arjan M G De Bruijn, Eric J Gustafson, Daniel M Kashian, Brian R Sturtevant, Douglass F JacobsAbstract:Observations of the rapid growth and slow decomposition of American chestnut (Castanea dentata (Marsh.) Borkh.) suggest that its reintroduction could enhance terrestrial carbon (C) sequestration. A suite of decomposition models was fit with decomposition data from coarse woody debris (CWD) sampled in Wisconsin and Virginia, U.S. The optimal (two-component exponential) model was integrated with generic growth curves and documented longevity and typical stem density to evaluate how CWD and biomass pools relate to decomposition. CWD decomposed faster in Wisconsin (4.3% ± 0.3% per year) than in Virginia (0.7% ± 0.01% per year), and downed dead wood decomposed faster (8.1% ± 1.9% per year) than standing dead wood (0.7% ± 0.0% per year). We predicted considerably smaller CWD pools in Wisconsin (maximum 41 ± 23 Mg C·ha-1) than in Virginia (maximum 98 ± 23 Mg C·ha-1); the predicted biomass pool was larger in the faster growing Wisconsin trees (maximum 542 ± 58 Mg C·ha-1) compared with slower growing trees in Virginia (maximum 385 ± 51 Mg C·ha-1). Sensitivity analysis indicated that accurate estimates of decomposition rates are more urgent in fertile locations where growth and decomposition are rapid. We conclude that the American chestnut wood is intermediate in resistance to decomposition. Due to the interrelatedness of growth and decomposition rates, CWD pool sizes likely do not depend on species alone but on how the growth and decomposition of individual species vary in response to site productivity.
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inter and intra specific competitiveness of plantation grown american chestnut Castanea dentata
Forest Ecology and Management, 2013Co-Authors: Martinmichel Gauthier, Kate E Zellers, Douglass F JacobsAbstract:Abstract The introduction of the fungal pathogen Cryphonectria parasitica (Murr.) Barr. decimated American chestnut ( Castanea dentata (Marsh.) Borkh.) throughout its native range in North America. A blight-resistant backcross hybrid form of American chestnut has been developed, and these backcross trees are likely to be incorporated into restoration programs in the near future. To help guide future afforestation efforts, this study examined juvenile (five growing seasons) morphological and physiological competitive aspects of American chestnut grown in a plantation setting with northern red oak ( Quercus rubra L.) and black cherry ( Prunus serotina Ehrh.) in Indiana, USA. Species were grown in seven possible species combinations including both monospecific and polyspecific combinations at three densities (1 × 1 m, 2 × 2 m, and 3 × 3 m). Despite an initial advantage in height, American chestnut exhibited the lowest relative height growth in the 2 × 2 and 3 × 3 m spacings, resulting in less total height compared to the other two species 5 years after planting. Relative height growth, as well as final absolute heights, were comparable among species in the 1 × 1 m spacing. Black cherry exhibited 2–3 times greater relative ground-line diameter (GLD) growth compared to oak and chestnut at all spacings. Linear regressions showed that growth was generally proportional to net photosynthesis ( A ) for all species. Increases in A likely resulted from increases in leaf nitrogen concentration. Chestnut exhibited lower A than cherry and oak in years 2 and 3, but no differences occurred in year 4. Additionally, chestnut had significantly higher predawn leaf water potential (leaf Ψ pd ) in year 4, reflecting greater drought stress in cherry and oak. While black cherry grew most aggressively, northern red oak and American chestnut performed acceptably, with high survival rates and moderate growth, especially in the 1 × 1 m spacing. American chestnut had the poorest stem form overall, but fared better in the 1 × 1 m spacing where the crown competition factor (CCF) was highest. Hence, an intermediate spacing between 1 × 1 and 2 × 2 m could optimize chestnut’s growth and stem form. Mixture effects may be attributed mainly to individual species growth characteristics rather than inter-specific interactions during this juvenile developmental stage.
Charles A Maynard - One of the best experts on this subject based on the ideXlab platform.
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chestnut american Castanea dentata marsh borkh
Methods of Molecular Biology, 2015Co-Authors: Charles A Maynard, Linda D Mcguigan, Allison D Oakes, Bo Zhang, Andrew E Newhouse, Lilibeth C Northern, Allison M Chartrand, Logan R Will, Kathleen M Baier, William A PowellAbstract:: The key to successful transformation of American chestnut is having the correct combination of explant tissue, selectable markers, a very robust DNA delivery system, and a reliable regeneration system. The most important components of this transformation protocol for American chestnut are the following: starting out with rapidly dividing somatic embryos, treating the embryos gently throughout the Agrobacterium inoculation and cocultivation steps, doing the cocultivation step in desiccation plates, and finally transferring the embryos into temporary-immersion bioreactors for selection. None of these departures from standard Agrobacterium transformation protocols is sufficient by itself to achieve transgenic American chestnut, but each component makes a difference, resulting in a highly robust protocol. The average transformation efficiency that can be expected using the described protocol is approximately 170 stable embryogenic transformation events per gram of somatic embryo tissue, a considerable improvement over the 20 transformation events per gram we reported in 2006 (Maynard et al. American chestnut (Castanea dentata (Marsh.) Borkh.) Agrobacterium protocols, 2nd ed., 2006). We have regenerated nearly 100 of these events, containing 23 different gene constructs, into whole plants. As of the fall of 2013, we had a total of 1,275 transgenic chestnut trees planted at eight locations in New York State and one in Virginia. Based on a combination of field-trial inoculations, greenhouse small-stem inoculations, and detached-leaf assays, we have identified three transgenes that produce stronger resistance to chestnut blight than non-transgenic American chestnut. Depending on the transgene and the event, this resistance can be either intermediate between American chestnut and Chinese chestnut, approximately equal to or even higher than the resistance naturally found in Chinese chestnut.
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the forest health initiative american chestnut Castanea dentata as a model for forest tree restoration biological research program
Acta Horticulturae, 2014Co-Authors: Dana C Nelson, Charles A Maynard, Andrew E Newhouse, Kathleen M Baier, Scott A Merkle, W A Powell, Campbell J Nairn, Lisheng Kong, John E Carlson, Charles AddoquayeAbstract:The Forest Health Initiative (FHI) was developed and implemented to test the hypothesis that a coordinated effort in biotechnology research could lead to resistant trees capable of restoring a species in a relevant time frame. As a test case, the American chestnut (Castanea dentata) was chosen for study as it is an iconic forest tree species in the eastern United States and southeastern Canada that has been nearly extirpated by chestnut blight which is caused by an introduced fungal pathogen (Cryphonectria parasitica). In addition, the species has attracted research investments over many decades, leading to some promising possibilities for effecting restoration. The FHI, now completing its third year, has integrated genomics-based candidate gene discovery with robust clonal propagation and gene transformation systems capable of producing hundreds of independent events for dozens of genes per year. A promising early leaf assay for blight reaction has been developed that will be instrumental in screening the large amount of material in production through these systems. Regulatory permits for testing some of the earliest transgene events have been obtained as small-scale field testing is beginning. High density genetic maps and various mapping populations are being analyzed to gain additional insights into the specific genes found in quantitative trait loci (QTLs) for resistances to blight and Phytophthora root rot (caused by P. cinnamomi, also known as ink disease). Nearly complete genome sequences of three of the blight resistance QTLs have been determined. These sequences are greatly assisting these analyses, as have comparisons with peach and other completed plant genomes, demonstrating the power of comparative genomics. These results show great promise for meeting the challenge proposed by the FHI hypothesis for American chestnut. In addition, other forest tree species under threat should benefit from similarly designed initiatives.
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a threshold level of oxalate oxidase transgene expression reduces cryphonectria parasitica induced necrosis in a transgenic american chestnut Castanea dentata leaf bioassay
Transgenic Research, 2013Co-Authors: Bo Zhang, Charles A Maynard, Allison D Oakes, Andrew E Newhouse, Kathleen M Baier, William A PowellAbstract:American chestnut (Castanea dentata) was transformed with a wheat oxalate oxidase (oxo) gene in an effort to degrade the oxalic acid (OA) secreted by the fungus Cryphonectria parasitica, thus decreasing its virulence. Expression of OxO was examined under two promoters: a strong constitutive promoter, CaMV 35S, and a predominantly vascular promoter, VspB. Oxo gene transcription was quantified by RT-qPCR. Relative expression of OxO varied approximately 200 fold among events produced with the 35S-OxO. The lowest 35S-OxO event expressed approximately 3,000 fold higher than the highest VspB-OxO event. This was potentially due to the tissue-specific nature of the VspB-controlled expression, the strength of the CaMV 35S constitutive promoter, or position effects. Leaf assays measuring necrotic lesion length were conducted to better understand the relationship between OxO expression level and the blight fungus in planta. A threshold response was observed between the OxO expression level and the C. parasitica lesion length. Five events of the 35S-OxO line showed significantly reduced lesion length compared to the blight-susceptible American chestnut. More importantly, the lesion length in these five events was reduced to the same level as the blight-resistant Chinese chestnut, C. mollissima. This is the first report on enhanced pathogen resistance in transgenic American chestnut.
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assessing ectomycorrhizal associations and transgene expression in transgenic Castanea dentata
BMC Proceedings, 2011Co-Authors: Katherine M Damico, Charles A Maynard, Thomas R Horton, William A PowellAbstract:Background American chestnut (Castanea dentata) once dominated the forests of the eastern United States until the introduction of a Chinese fungal pathogen Cryphonectria parasitica(causal agent of the chestnut blight) decimated the species. This tree was important not only ecologically, but also played a significant role economically. Restoration programs are implementing a variety of techniques, including genetic transformation, to develop a blight resistant tree that can be reintroduced into the native chestnut range (S.A. Merkle, 2007, Tree Genetics and Genomics, 3, 111-18). Specific genes involved in plant defense responses are being introduced into American chestnut via Agrobacterium-mediated transformation, with the hope that one gene or a combination of genes will aid in chestnut defense against blight (L.D. Polin, 2006, Plant Cell, Tissue, and Organ Culture, 84, 69-79). One gene of particular interest to the transgenic project is oxalate oxidase, a defense related gene from wheat that has also been shown to enhance the defense response of other plants when introduced through genetic transformation (H. Liang, 2001, Plant Molecular Biology, 45, 619-29). American chestnut transformation with a binary vector containing oxalate oxidase has produced a number of transgenic events, many of which have already been regenerated plants (unpublished data). Before releasing any transgenic plant it is necessary to assess any non-target impacts the introduced genes may have on associated microbial communities. C. parasiticais a fungal pathogen, so we are particularly interested in studying the effects of any transgene on the symbiotic relationship between the host plant and mycorrhizaeforming fungi. Prior studies have examined the potential impact of transgenic plants on ectomycorrhizal fungi (K. L. Oliver, 2008, Applied and Environmental Microbiology, 74, 5340-48).
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the effects of oxalic acid on transgenic Castanea dentata callus tissue expressing oxalate oxidase
Plant Science, 2007Co-Authors: Andreanna J Welch, Charles A Maynard, Arthur J Stipanovic, William A PowellAbstract:The American chestnut, Castanea dentata (Marsh.) Borkh, has been decimated by chestnut blight which is caused by an exotic, oxalate producing pathogen, Cryphonectria parasitica (Murrill.) Barr. Many pathogenic and saprophytic fungi produce oxalate to facilitate in colonization of plant tissue, and therefore, discovering ways to protect plants from the detrimental effects of oxalate could be very beneficial. Germin-like oxalate oxidases have been found to degrade oxalate into hydrogen peroxide and carbon dioxide. Hydrogen peroxide plays several important roles in plant defense, including lignification of the plant cell wall. In this study, American chestnut wildtype callus tissue and callus tissue transformed with an oxalate oxidase gene were cultured on media containing various concentrations of oxalic acid. Thermogravimetric analysis (TGA) was employed to test the cellulose, hemicellulose, and lignin content of the calli. In the presence of oxalic acid, wildtype tissues demonstrated a significant decrease in lignin content and increase in cellulose content, while transformed tissues did not. Transforming American chestnut with an oxalate oxidase gene may prove to be useful in preventing changes in the cell wall composition caused by the oxalate produced during C. parasitica infection and could possibly enhance resistance.
Stacy L Clark - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the first test plantings using BC3F3 seedlings on National Forests in the Southern Region
2020Co-Authors: Stacy L Clark, Scott E SchlarbaumAbstract:Background An exotic pathogen, Cryphonectria parasitica (Murr. Barr), popularly known as the chestnut blight, decimated the American chestnut (Castanea dentata Marsh. Borkh.) tree throughout eastern North America in the first half of the 20 century. American chestnut was a keystone species in the eastern hardwood forests, comprising 25 to 50 percent of total tree density. The species’ demise likely had drastic and sometimes negative consequences to forest structure and function, such as reductions in hard mast availability, increased light to the forest floor, and changes in soil chemistry. The species was perhaps the most widely used tree for utilitarian purposes in eastern North American. The tree was highly valued for tanning of leather, lumber, food, and fodder for cattle.
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Effects of simulated prescribed fire on American chestnut and northern red oak regeneration
2020Co-Authors: Ethan P Belair, Michael R Saunders, Stacy L ClarkAbstract:American chestnut (Castanea dentata [Marsh.] Borkh.) was a dominant species in the forests of eastern North America prior to the importation of chestnut blight (Cryphonectria parasitica [Murr.] Barr) in the early 1900s and ink disease (Phytophthora cinnamomi Rands) in the 1800s (Anagnostakis 2012). Historical accounts and phylogeny (Manos et al. 2001) suggest chestnut may have certain disturbance adaptations similar to oak (Quercus spp.), including the ability to prolifically sprout following topkill (Paillet 2002). However, the response of chestnut to fire has only been observed in mature individuals, not in seedlings which would be used during restoration attempts. The objective of this study was to compare American chestnut's response to prescribed fire to that of the closely related red oak (Q. rubra L.). We hypothesized that available light and initial stem diameter would positively affect the vigor of sprouts produced (Dey 1991, Johnson et al. 2002).
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eight year blight cryphonectria parasitica resistance of backcross generation american chestnuts Castanea dentata planted in the southeastern united states
Forest Ecology and Management, 2019Co-Authors: Stacy L Clark, Scott E Schlarbaum, Arnold M Saxton, Richard E BairdAbstract:Abstract The loss of American chestnut (Castanea dentata) in eastern North America to chestnut blight, a disease caused by the fungal pathogen (Cryphonectria parasitica), has devastated ecological and utilitarian processes and functions. A backcross breeding approach has been developed to confer disease resistance to hybrid seedlings, and forest reintroduction trials will provide important information on performance and durability of resistance in real-world forest conditions. Three plantings were established in 2009 in mesic, even-aged regeneration harvests (site index averaged 23 m for Quercus rubra) and were examined for eight-year blight resistance. These plantings are the first forest field trials to test blight resistance of the most advanced breeding generation currently available, the third generation of the third backcross (BC3F3), against less advanced breeding generations (BC1F3, BC2F3), disease-resistant Chinese chestnut (C. mollissima), and disease-susceptible American chestnut. We also examined if C. parasitica infection was related to tree size and growth. The pathogen infected 36 percent of trees across locations by year 8, but 31 percent of trees died prior to detection of infection. Non-pathogen related mortality was probably due to factors that are typical of hardwood plantings, including repeated deer browsing and native and non-native pest damage. The BC3F3 generation exhibited resistance more similar to the Chinese chestnut than the American chestnut, but exhibited significantly lower resistance than Chinese chestnut at the location with the highest blight incidence; genetic family differences among BC3F3 progeny were significant at this location. Interactions between planting location and breeding generation affected resistance rankings, suggesting additional or longer-term testing is needed to determine resistance of a particular breeding line across a variety of sites. Probability of disease incidence was positively related to ground-line diameter (GLD), but this relationship depended on location and breeding type. At two locations, American chestnut had 50 percent probability of C. parasitica infection when GLD was approximately 70 mm, and the BC3F3 had 50 percent probability when GLD was between 93 and 126 mm. The Chinese chestnut maintained low probability of disease incidence (
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leaf physiology and morphology of Castanea dentata marsh borkh Castanea mollissima blume and three backcross breeding generations planted in the southern appalachians usa
New Forests, 2014Co-Authors: Geoff G Wang, Stacy L Clark, Benjamin O Knapp, Lauren S Pile, Scott E SchlarbaumAbstract:Backcross breeding programs have been used to transfer disease resistance and other traits from one forest tree species to another in order to meet restoration objectives. Evaluating the field performance of such material is critical for determining the success of breeding programs. In eastern North America, The American Chestnut Foundation has a backcross breeding program that uses Chinese chestnut (Castanea mollissima Blume) to introduce resistance of the fungal pathogen chestnut blight [Cryphonectria parasitica (Murr.) Barr.] to the native American chestnut [Castanea dentata (Marsh.) Borkh.]. We compared physiological and morphological characteristics among seedlings of American chestnut, Chinese chestnut, and BC1F3, BC2F3, and BC3F3 hybrid chestnuts during their fourth growing season after field-planting. American chestnut and the BC3F3 breeding generation displayed photosynthetic light-response curves that were similar to each other but different from Chinese chestnut. Rates of photosynthesis were higher for American chestnut and the BC3F3 breeding generation when compared to Chinese chestnut for light levels ≥800 μmol m−2 s−1 photosynthetic photon flux density and for maximum photosynthetic capacity. Leaf morphology variables were not different between American chestnut and any of the breeding generations, but leaf area (on a per leaf basis) of Chinese chestnut was lower than that of any other chestnut type. Our results suggest that backcross breeding can be used to transfer desirable traits for restoration of native species threatened by non-native pathogens.
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lessons from the field the first tests of restoration american chestnut Castanea dentata seedlings planted in the southern region
In: Butnor John R. ed. 2012. Proceedings of the 16th biennial southern silvicultural research conference. e-Gen. Tech. Rep. SRS-156. Asheville NC: U.S, 2012Co-Authors: Stacy L Clark, Scott E Schlarbaum, Fred Hebard, John Saxton, John Blanton, David M Casey, Barbara S Crane, Russ Macfarlane, Jason A RodrigueAbstract:An exotic fungus, the chestnut blight (Cryphonectria parasitica Murr. Barr), decimated the American chestnut tree (Castanea dentata Marsh. Borkh.) throughout eastern North America in the first half of the 20th century. The United States Department of Agriculture, Forest Service (FS), The University of Tennessee, and The American Chestnut Foundation (TACF) are collaborating on chestnut restoration research on National Forest System lands. In autumn 2007 and 2008, TACF used a back-cross breeding technique (Hebard 2001) to produce chestnuts, referred to as the BC3F3 generation, that are predicted to be American chestnut in character with blight resistance from Chinese chestnut (Castanea mollissima Blume).
Scott E Schlarbaum - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the first test plantings using BC3F3 seedlings on National Forests in the Southern Region
2020Co-Authors: Stacy L Clark, Scott E SchlarbaumAbstract:Background An exotic pathogen, Cryphonectria parasitica (Murr. Barr), popularly known as the chestnut blight, decimated the American chestnut (Castanea dentata Marsh. Borkh.) tree throughout eastern North America in the first half of the 20 century. American chestnut was a keystone species in the eastern hardwood forests, comprising 25 to 50 percent of total tree density. The species’ demise likely had drastic and sometimes negative consequences to forest structure and function, such as reductions in hard mast availability, increased light to the forest floor, and changes in soil chemistry. The species was perhaps the most widely used tree for utilitarian purposes in eastern North American. The tree was highly valued for tanning of leather, lumber, food, and fodder for cattle.
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The importance of site quality to backcross chestnut establishment success
2020Co-Authors: Cornelia C. Pinchot, Scott E Schlarbaum, Alejandro A. Royo, Matthew P. Peters, Sandra L. AnagnostakisAbstract:Short-term studies show that American chestnut (Castanea dentata) grows faster on mesic compared to xeric sites. Long-term impacts of site quality and corresponding moisture and nutrient availability on backcross chestnut establishment success and resistance to the chestnut blight fungus, Cryphonectria parasitica, however, have not been evaluated. We report here the first year results from a study designed to evaluate the effects of three site quality treatments—mesic, xeric, and intermediate—on the establishment success and blight resistance of chestnut seedlings planted on the Allegheny Plateau in northwestern Pennsylvania. We hypothesized that long-term chestnut growth and competitive ability will be greatest on sites intermediate in resource availability, and severity of blight will be lowest on mesic sites.
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eight year blight cryphonectria parasitica resistance of backcross generation american chestnuts Castanea dentata planted in the southeastern united states
Forest Ecology and Management, 2019Co-Authors: Stacy L Clark, Scott E Schlarbaum, Arnold M Saxton, Richard E BairdAbstract:Abstract The loss of American chestnut (Castanea dentata) in eastern North America to chestnut blight, a disease caused by the fungal pathogen (Cryphonectria parasitica), has devastated ecological and utilitarian processes and functions. A backcross breeding approach has been developed to confer disease resistance to hybrid seedlings, and forest reintroduction trials will provide important information on performance and durability of resistance in real-world forest conditions. Three plantings were established in 2009 in mesic, even-aged regeneration harvests (site index averaged 23 m for Quercus rubra) and were examined for eight-year blight resistance. These plantings are the first forest field trials to test blight resistance of the most advanced breeding generation currently available, the third generation of the third backcross (BC3F3), against less advanced breeding generations (BC1F3, BC2F3), disease-resistant Chinese chestnut (C. mollissima), and disease-susceptible American chestnut. We also examined if C. parasitica infection was related to tree size and growth. The pathogen infected 36 percent of trees across locations by year 8, but 31 percent of trees died prior to detection of infection. Non-pathogen related mortality was probably due to factors that are typical of hardwood plantings, including repeated deer browsing and native and non-native pest damage. The BC3F3 generation exhibited resistance more similar to the Chinese chestnut than the American chestnut, but exhibited significantly lower resistance than Chinese chestnut at the location with the highest blight incidence; genetic family differences among BC3F3 progeny were significant at this location. Interactions between planting location and breeding generation affected resistance rankings, suggesting additional or longer-term testing is needed to determine resistance of a particular breeding line across a variety of sites. Probability of disease incidence was positively related to ground-line diameter (GLD), but this relationship depended on location and breeding type. At two locations, American chestnut had 50 percent probability of C. parasitica infection when GLD was approximately 70 mm, and the BC3F3 had 50 percent probability when GLD was between 93 and 126 mm. The Chinese chestnut maintained low probability of disease incidence (
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leaf physiology and morphology of Castanea dentata marsh borkh Castanea mollissima blume and three backcross breeding generations planted in the southern appalachians usa
New Forests, 2014Co-Authors: Geoff G Wang, Stacy L Clark, Benjamin O Knapp, Lauren S Pile, Scott E SchlarbaumAbstract:Backcross breeding programs have been used to transfer disease resistance and other traits from one forest tree species to another in order to meet restoration objectives. Evaluating the field performance of such material is critical for determining the success of breeding programs. In eastern North America, The American Chestnut Foundation has a backcross breeding program that uses Chinese chestnut (Castanea mollissima Blume) to introduce resistance of the fungal pathogen chestnut blight [Cryphonectria parasitica (Murr.) Barr.] to the native American chestnut [Castanea dentata (Marsh.) Borkh.]. We compared physiological and morphological characteristics among seedlings of American chestnut, Chinese chestnut, and BC1F3, BC2F3, and BC3F3 hybrid chestnuts during their fourth growing season after field-planting. American chestnut and the BC3F3 breeding generation displayed photosynthetic light-response curves that were similar to each other but different from Chinese chestnut. Rates of photosynthesis were higher for American chestnut and the BC3F3 breeding generation when compared to Chinese chestnut for light levels ≥800 μmol m−2 s−1 photosynthetic photon flux density and for maximum photosynthetic capacity. Leaf morphology variables were not different between American chestnut and any of the breeding generations, but leaf area (on a per leaf basis) of Chinese chestnut was lower than that of any other chestnut type. Our results suggest that backcross breeding can be used to transfer desirable traits for restoration of native species threatened by non-native pathogens.
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lessons from the field the first tests of restoration american chestnut Castanea dentata seedlings planted in the southern region
In: Butnor John R. ed. 2012. Proceedings of the 16th biennial southern silvicultural research conference. e-Gen. Tech. Rep. SRS-156. Asheville NC: U.S, 2012Co-Authors: Stacy L Clark, Scott E Schlarbaum, Fred Hebard, John Saxton, John Blanton, David M Casey, Barbara S Crane, Russ Macfarlane, Jason A RodrigueAbstract:An exotic fungus, the chestnut blight (Cryphonectria parasitica Murr. Barr), decimated the American chestnut tree (Castanea dentata Marsh. Borkh.) throughout eastern North America in the first half of the 20th century. The United States Department of Agriculture, Forest Service (FS), The University of Tennessee, and The American Chestnut Foundation (TACF) are collaborating on chestnut restoration research on National Forest System lands. In autumn 2007 and 2008, TACF used a back-cross breeding technique (Hebard 2001) to produce chestnuts, referred to as the BC3F3 generation, that are predicted to be American chestnut in character with blight resistance from Chinese chestnut (Castanea mollissima Blume).