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Full-Text Articles in Physical Sciences and Mathematics
Evaluation Of Blight Resistance In Chestnut F2 Half-Sibling And Full-Sibling Families Via Small Stem Assay, Kevin Gentner
Evaluation Of Blight Resistance In Chestnut F2 Half-Sibling And Full-Sibling Families Via Small Stem Assay, Kevin Gentner
Honors Theses
In 1904, Cryphonectria parasitica, the causal agent for chestnut blight, was imported into North America on chestnut nursery stock from China. Fifty-five years later, nearly all full-grown wild American chestnut trees (Castanea dentata) were dead. A century of work has been put into restoring the American chestnut to its rightful place among the forest canopy. Since the 1980s, The American Chestnut Foundation has pursued backcross breeding to introgress blight resistance into C. dentata from the resistant Chinese species (C. mollissima), and has used progeny testing to make predictions about parental resistance in B3F2 chestnuts. We performed a small stem assay …
Conservation And Collection Of Castanea Dentata Germplasm In The South, Trent Deason
Conservation And Collection Of Castanea Dentata Germplasm In The South, Trent Deason
Honors Theses
The American chestnut, Castanea dentata, has been devastated by the exotic invasive pathogens Cryphonectria parasitica and Phytophthora cinnamomi to which it has no resistance. The American Chestnut Foundation (TACF) has developed an interspecific backcross breeding program to introgress disease resistance from Asian chestnut species, primarily Castanea mollissima, into C. dentata hybrid populations. The genetic base of this program can be expanded by utilizing vegetative propagation through grafting in order to collect and conserve American chestnut individuals not amenable to traditional breeding. As the majority of the surviving American chestnuts are confined to the understory, they are shaded out by the …
Implementing Early Screening Methods To Detect Resistance To Phytophthora Cinnamomi In Backcross Chinese-American Chestnut Hybrids, Kirsten Hein
Honors Theses
Phytophthora root rot (PRR), caused by the oomycete Phytophthora cinnamomi Rands., is one of the two greatest obstacles to survival of American chestnut (Castanea dentata Borkh.). The other is chestnut blight, caused by the ascomycete Cryphonectria parasitica (Murr.) Barr. Developing early and reliable PRR screening methods can facilitate the efficient introgression of PRR resistance from Chinese chestnut (C. mollissima Blume.) into the populations of potentially chestnut blight resistant trees currently under development by The American Chestnut Foundation (TACF). This study tests the efficacy of a method for early identification of PRR-resistant hybrid chestnuts in a greenhouse/nursery setting. The chestnut blight …
Measuring Phytophthora Resistance Phenotypes In Segregating Testcross Families Of Hybrid American Chestnut Trees, Anna C. Robinson
Measuring Phytophthora Resistance Phenotypes In Segregating Testcross Families Of Hybrid American Chestnut Trees, Anna C. Robinson
Honors Theses
Phytophthora root rot (PRR), caused by the oomycete Phytophthora cinnamomi Rands, is a formidable obstacle to the restoration of Castanea dentata Marsh. commonly known as the American chestnut. Genetic resistance to PRR has been observed in Asian species of chestnut including C. mollissima Blume, and in interspecific hybrids between C. mollissima and C. dentata. We hypothesized that root rot resistance alleles would segregate in a 1:1 ratio within progeny of crosses between PRR resistant F1 hybrids and PRR-susceptible American chestnut trees (first-backcrosses), and that PRR resistance could be successfully passed down to all families of first-backcross hybrids. To test these …
Not Extinct: A Year In The Life Of The American Chesnut, Kristen Julina Stanfill
Not Extinct: A Year In The Life Of The American Chesnut, Kristen Julina Stanfill
Honors Theses
After the widespread infection of the American chestnut tree (Castanea dentata) due to the fungus Cryphonectria parasitica the species was nearly brought to extinction and now merely exists as stump sprouts. Since the fungus infects the bark of the tree but not the root systems new shoots are able to emerge and grow before once again being girdled by the fungus. Cryphonectria parasitica is believed to have been brought to America on Asian species of chestnut which possess resistance to the blight caused by the fungus. It is the plan of the American Chestnut Foundation (TACF) to integrate the genes …
The Effect Of Phosphite On Mycorrhiza Formation In American Chestnut (Castanea Dentata), Matthew T. Perkins
The Effect Of Phosphite On Mycorrhiza Formation In American Chestnut (Castanea Dentata), Matthew T. Perkins
Honors Theses
One of the primary hindrances to Castanea dentata restoration in the Southeast is the root rot disease caused by the fungus-like microorganism Phytophthora cinnamomi. Root rot can be combated by the application of mono- and di-potassium salts of phosphorous acid, which are marketed as phosphite fungicides. Despite its value in preventing infection by P. cinnamomi it is also thought that phosphite may impede root colonization by beneficial, ectomycorrhizal fungi. I hypothesized that plants given a routine application of phosphite will display fewer mycorrhizas in the root tips than those plants that were not treated with potassium phosphite. Therefore I attempted …
Conversion Of Virulent Cryphonectria Parasitica From The Lula Lake Land Trust To Hypovirulent Strains, Pearl Hwang
Conversion Of Virulent Cryphonectria Parasitica From The Lula Lake Land Trust To Hypovirulent Strains, Pearl Hwang
Honors Theses
For almost a century, the fungus, Cryphonectria parasitica has existed in the United States as a wound parasite to American chestnut (Castanea dentata) trees. However, hypovirulence, evidence of spontaneous healing in Italy and Michigan, has given the American chestnut trees hope to one day be restored into its natural range. Viruses were the cause of such spontaneous healings. My hypothesis was that a viruscontaining hypovirulent strain of C. parasitica (in a brown background) would share alleles that control anastomoses with the local virulent strains, so a virus that causes hypovirulence could be transmitted into local virulent strains in vitro. Fifty …