scholarly journals Effects of Temporal Dynamics, Nut Weight and Nut Size on Growth of American Chestnut, Chinese Chestnut and Backcross Generations in a Commercial Nursery

Forests ◽  
2015 ◽  
Vol 6 (12) ◽  
pp. 1537-1556 ◽  
Author(s):  
Cornelia Pinchot ◽  
Stacy Clark ◽  
Scott Schlarbaum ◽  
Arnold Saxton ◽  
Shi-Jean Sung ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
American Chestnut ◽  
Chinese Chestnut

scholarly journals Comparison of the transcriptomes of American chestnut (Castanea dentata) and Chinese chestnut (Castanea mollissima) in response to the chestnut blight infection

2009 ◽  
Vol 9 (1) ◽  
pp. 51 ◽  
Author(s):  
Abdelali Barakat ◽  
Denis S DiLoreto ◽  
Yi Zhang ◽  
Chris Smith ◽  
Kathleen Baier ◽  
...  
Keyword(s):  
Castanea Dentata ◽  
American Chestnut ◽  
Chestnut Blight ◽  
Chinese Chestnut ◽  
Castanea Mollissima

scholarly journals Resistance toPhytophthora cinnamomiin American Chestnut (Castanea dentata) Backcross Populations that Descended from Two Chinese Chestnut (Castanea mollissima) Sources of Resistance

Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1631-1641 ◽  
Author(s):  
Jared W. Westbrook ◽  
Joseph B. James ◽  
Paul H. Sisco ◽  
John Frampton ◽  
Sunny Lucas ◽  
...  
Keyword(s):  
Phytophthora Cinnamomi ◽  
Seedling Survival ◽  
Cryphonectria Parasitica ◽  
Castanea Dentata ◽  
American Chestnut ◽  
Chestnut Blight ◽  
Sources Of Resistance ◽  
Backcross Population ◽  
Chinese Chestnut ◽  
Root Health

Restoration of American chestnut (Castanea dentata) depends on combining resistance to both the chestnut blight fungus (Cryphonectria parasitica) and Phytophthora cinnamomi, which causes Phytophthora root rot, in a diverse population of C. dentata. Over a 14-year period (2004 to 2017), survival and root health of American chestnut backcross seedlings after inoculation with P. cinnamomi were compared among 28 BC3, 66 BC4, and 389 BC3F3families that descended from two BC1trees (Clapper and Graves) with different Chinese chestnut grandparents. The 5% most resistant Graves BC3F3families survived P. cinnamomi infection at rates of 75 to 100% but had mean root health scores that were intermediate between resistant Chinese chestnut and susceptible American chestnut families. Within Graves BC3F3families, seedling survival was greater than survival of Graves BC3and BC4families and was not genetically correlated with chestnut blight canker severity. Only low to intermediate resistance to P. cinnamomi was detected among backcross descendants from the Clapper tree. Results suggest that major-effect resistance alleles were inherited by descendants from the Graves tree, that intercrossing backcross trees enhances progeny resistance to P. cinnamomi, and that alleles for resistance to P. cinnamomi and C. parasitica are not linked. To combine resistance to both C. parasitica and P. cinnamomi, a diverse Graves backcross population will be screened for resistance to P. cinnamomi, survivors bred with trees selected for resistance to C. parasitica, and progeny selected for resistance to both pathogens will be intercrossed.

scholarly journals The Chinese chestnut genome: a reference for species restoration

2019 ◽  
Author(s):  
Margaret Staton ◽  
Charles Addo-Quaye ◽  
Nathaniel Cannon ◽  
Yongshuai Sun ◽  
Tetyana Zhebentyayeva ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Resistance Genes ◽  
Tree Species ◽  
Related Species ◽  
Forest Health ◽  
American Chestnut ◽  
Sources Of Resistance ◽  
Chinese Chestnut ◽  
Exotic Pests ◽  
Species Restoration

AbstractForest tree species are increasingly subject to severe mortalities from exotic pests, diseases, and invasive organisms, accelerated by climate change. Forest health issues are threatening multiple species and ecosystem sustainability globally. While sources of resistance may be available in related species, or among surviving trees, introgression of resistance genes into threatened tree species in reasonable time frames requires genome-wide breeding tools. Asian species of chestnut (Castaneaspp.) are being employed as donors of disease resistance genes to restore native chestnut species in North America and Europe. To aid in the restoration of threatened chestnut species, we present the assembly of a reference genome with chromosome-scale sequences for Chinese chestnut (C. mollissima), the disease-resistance donor for American chestnut restoration. We also demonstrate the value of the genome as a platform for research and species restoration, including new insights into the evolution of blight resistance in Asian chestnut species, the locations in the genome of ecologically important signatures of selection differentiating American chestnut from Chinese chestnut, the identification of candidate genes for disease resistance, and preliminary comparisons of genome organization with related species.

Influence of species and hybrid status on induction of somatic embryogenesis in Castanea

2017 ◽  
Vol 47 (3) ◽  
pp. 382-388 ◽  
Author(s):  
C.T. Holtz ◽  
A.R. Tull ◽  
S.A. Merkle
Keyword(s):  
Somatic Embryogenesis ◽  
Field Tests ◽  
Castanea Sativa ◽  
American Chestnut ◽  
Embryogenic Tissue ◽  
Culture Initiation ◽  
Chinese Chestnut ◽  
European Chestnut ◽  
Castanea Sativa Mill ◽  
And Control

The American chestnut (AC; Castanea dentata (Marsh.) Borkh.) once dominated the forests of eastern North America prior to the introduction of chestnut blight in the late 19th century. A somatic embryogenesis (SE) system developed for American chestnut is potentially applicable for clonally propagating blight-resistant trees produced by The American Chestnut Foundation’s hybrid backcross breeding program. In this program, AC trees are hybridized with blight-resistant Chinese chestnut (CC; Castanea mollissima Blume) trees, followed by multiple generations of backcrossing to AC trees. It is possible, however, that the proportion of CC parental contribution in the hybrid backcross material could affect the success of SE using the AC protocol. Over three years of culture initiations, we tested the effects of the relative parental contributions of AC and CC on the success of SE induction using our standard AC culture initiation protocol and, subsequently, a published protocol for SE in European chestnut (Castanea sativa Mill.). With our standard AC protocol, open-pollinated AC and open- and control-pollinated hybrid backcross BC3F3 seed explants, as well as open-pollinated BC2 seed explants, successfully produced embryogenic tissue, while CC, F1, and BC1 explants did not. The European chestnut protocol produced Chinese chestnut embryogenic tissue and, subsequently, somatic embryos. The first BC3F3 somatic seedlings are currently growing in field tests.

scholarly journals Dissecting Resistance to Phytophthora cinnamomi in Interspecific Hybrid Chestnut Crosses Using Sequence-Based Genotyping and QTL Mapping

2019 ◽  
Vol 109 (9) ◽  
pp. 1594-1604 ◽  
Author(s):  
Tetyana N. Zhebentyayeva ◽  
Paul H. Sisco ◽  
Laura L. Georgi ◽  
Steven N. Jeffers ◽  
M. Taylor Perkins ◽  
...  
Keyword(s):  
Plant Species ◽  
Phytophthora Cinnamomi ◽  
The United States ◽  
Climatic Conditions ◽  
American Chestnut ◽  
Medium Effect ◽  
Linkage Maps ◽  
Natural Ecosystems ◽  
Chinese Chestnut ◽  
Stem Lesions

The soilborne oomycete Phytophthora cinnamomi—which causes root rot, trunk cankers, and stem lesions on an estimated 5,000 plant species worldwide—is a lethal pathogen of American chestnut (Castanea dentata) as well as many other woody plant species. P. cinnamomi is particularly damaging to chestnut and chinquapin trees (Castanea spp.) in the southern portion of its native range in the United States due to relatively mild climatic conditions that are conductive to disease development. Introduction of resistant genotypes is the most practical solution for disease management in forests because treatment with fungicides and eradication of the pathogen are neither practical nor economically feasible in natural ecosystems. Using backcross families derived from crosses of American chestnuts with two resistant Chinese chestnut cultivars Mahogany and Nanking, we constructed linkage maps and identified quantitative trait loci (QTLs) for resistance to P. cinnamomi that had been introgressed from these Chinese chestnut cultivars. In total, 957 plants representing five cohorts of three hybrid crosses were genotyped by sequencing and phenotyped by standardized inoculation and visual examination over a 6-year period from 2011 to 2016. Eight parental linkage maps comprising 7,715 markers were constructed, and 17 QTLs were identified on four linkage groups (LGs): LG_A, LG_C, LG_E, and LG_K. The most consistent QTLs were detected on LG_E in seedlings from crosses with both ‘Mahogany’ and ‘Nanking’ and LG_K in seedlings from ‘Mahogany’ crosses. Two consistent large and medium effect QTLs located ∼10 cM apart were present in the middle and at the lower end of LG_E; other QTLs were considered to have small effects. These results imply that the genetic architecture of resistance to P. cinnamomi in Chinese chestnut × American chestnut hybrid progeny may resemble the P. sojae–soybean pathosystem, with a few dominant QTLs along with quantitatively inherited partial resistance conferred by multiple small-effect QTLs.

Nut cold hardiness as a factor influencing the restoration of American chestnut in northern latitudes and high elevations

2012 ◽  
Vol 42 (5) ◽  
pp. 849-857 ◽  
Author(s):  
Thomas M. Saielli ◽  
Paul G. Schaberg ◽  
Gary J. Hawley ◽  
Joshua M. Halman ◽  
Kendra M. Gurney
Keyword(s):  
Cold Tolerance ◽  
Cold Hardiness ◽  
Forest Tree ◽  
Cryphonectria Parasitica ◽  
Preliminary Evidence ◽  
American Chestnut ◽  
Red Oak ◽  
Freezing Damage ◽  
Chinese Chestnut ◽  
Cold Tolerant

American chestnut ( Castanea dentata (Marsh.) Borkh.) was functionally removed as a forest tree by chestnut blight (caused by the fungal pathogen Cryphonectria parasitica (Murr.) Barr). Hybrid-backcross breeding between blight-resistant Chinese chestnut ( Castanea mollissima Blume) and American chestnut is used to support species restoration. However, preliminary evidence suggests that backcross material may not have the cold hardiness needed for restoration in the northern portions of the species’ range. The cold tolerance of nuts is of concern because reproductive tissues are particularly sensitive to freezing damage. We assessed nut cold tolerance for 16 American chestnut, four Chinese chestnut, and four red oak ( Quercus rubra L.) (a native competitor) sources to better assess genetic variation in nut hardiness. We found that Chinese chestnut nuts were less cold tolerant than American chestnut and red oak nuts and that American chestnut sources from the south were less cold tolerant than sources from the north, with significant differences among sources within all regions. We also assessed how sources varied among temperature zones (sources separated by average winter temperature lows at source locations). Sources from the cold temperature zone were more cold tolerant and less variable in hardiness than sources from warm and moderate zones.

Effects of Monetary Incentives on Task Switching

2012 ◽  
Vol 59 (4) ◽  
pp. 216-226 ◽  
Author(s):  
Thomas Kleinsorge ◽  
Gerhard Rinkenauer
Keyword(s):  
Task Switching ◽  
Temporal Dynamics ◽  
Reward Processing ◽  
General Level ◽  
Monetary Incentives ◽  
Switch Costs ◽  
Expectancy Effect ◽  
Reward Expectancy ◽  
Trial Basis

In two experiments, effects of incentives on task switching were investigated. Incentives were provided as a monetary bonus. In both experiments, the availability of a bonus varied on a trial-to-trial basis. The main difference between the experiments relates to the association of incentives to individual tasks. In Experiment 1, the association of incentives to individual tasks was fixed. Under these conditions, the effect of incentives was largely due to reward expectancy. Switch costs were reduced to statistical insignificance. This was true even with the task that was not associated with a bonus. In Experiment 2, there was a variable association of incentives to individual tasks. Under these conditions, the reward expectancy effect was bound to conditions with a well-established bonus-task association. In conditions in which the bonus-task association was not established in advance, enhanced performance of the bonus task was accompanied by performance decrements with the task that was not associated with a bonus. Reward expectancy affected mainly the general level of performance. The outcome of this study may also inform recently suggested neurobiological accounts about the temporal dynamics of reward processing.

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