Christina Wells | Clemson University (original) (raw)
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Papers by Christina Wells
Http Dx Doi Org 10 1080 01904160903470497, Jan 8, 2010
The relationship between root age and root physiology is poorly understood, despite its importanc... more The relationship between root age and root physiology is poorly understood, despite its importance for nutrient absorption. In peaches, roots are white when they first appear and then become brown with age, which corresponds to a number of physiological changes. We related root ...
PLOS ONE, 2015
Low-cost, high throughput genotyping methods are crucial to marker discovery and marker-assisted ... more Low-cost, high throughput genotyping methods are crucial to marker discovery and marker-assisted breeding efforts, but have not been available for many 'specialty crops' such as fruit and nut trees. Here we apply the Genotyping-By-Sequencing (GBS) method developed for cereals to the discovery of single nucleotide polymorphisms (SNPs) in a peach F2 mapping population. Peach is a genetic and genomic model within the Rosaceae and will provide a template for the use of this method with other members of this family. Our F2 mapping population of 57 genotypes segregates for bloom time (BD) and chilling requirement (CR) and we have extensively phenotyped this population. The population derives from a selfed F1 progeny of a cross between 'Hakuho' (high CR) and 'UFGold' (low CR). We were able to successfully employ GBS and the TASSEL GBS pipeline without modification of the original methodology using the ApeKI restriction enzyme and multiplexing at an equivalent of 96 samples per Illumina HiSeq 2000 lane. We obtained hundreds of SNP markers which were then used to construct a genetic linkage map and identify quantitative trait loci (QTL) for BD and CR.
VI International Peach Symposium, 2006
The foliar nematode Aphelenchoides fragariae (Aphelenchida: Aphelenchidae) is an endo- and ectopa... more The foliar nematode Aphelenchoides fragariae (Aphelenchida: Aphelenchidae) is an endo- and ectoparasite that feeds on aerial parts of over 250 plant species from 47 families. It is a common and economically-damaging pest of nursery-grown crops including ferns, foliage and flowering plants, and herbaceous and woody perennials. We used Illumina HiSeq 2000 technology and the Trinity de novo assembler (trinityrnaseq.sourceforge.net/) to produce a transcriptome of A. fragariae from four growth conditions (fungal-fed, plant-fed, diet-changed, and desiccated). High throughput sequencing generated 43 million reads with average length of 100-bp. Assembly of the pooled read set generated 95,930 contigs, corresponding to 50,686 unigenes (mean length = 605 bp) with 45,244 alternate splice variants. Fifty-two percent of the unigenes (26,389) had homology to known genes or proteins in the NCBI non-redundant database, and 20,558 were assigned GO terms based on these homologies by Blast2Go software...
Journal of Plant Nutrition, 2010
The relationship between root age and root physiology is poorly understood, despite its importanc... more The relationship between root age and root physiology is poorly understood, despite its importance for nutrient absorption. In peaches, roots are white when they first appear and then become brown with age, which corresponds to a number of physiological changes. We related root ...
Douglas G. Bielenberg: A.
Germanium has been reported as a mineral element affecting plant cell metabolism. Many trials to ... more Germanium has been reported as a mineral element affecting plant cell metabolism. Many trials to supply germanium to fruit have been carried out since tests have confi rmed germanium's role as a medical substance. Supplying germanium to orchards by soil and foliar application was not effective because of loss from rainfall. Also, tree injection with germanium solution required the insertion of a tube to the tree xylem at each injection site. In order to increase germanium absorption by fruit, this study carried out the postharvest dipping of fruit into germanium solution. 'Niitaka' pear ( Pyrus pyrifolia ) fruit was treated with two types of germanium, GeO (inorganic type) and Ge-132 (organic type), in a concentration of 50 mg·L -1 just after harvest in early Oct. 2004. Flesh browning after peeling the fruit was delayed by germanium treatment, and polyphenoloxidase (PPO) activities were lowered. Postharvest potentials were maintained at high levels for fruit fi rmness, physiological disorders, and decayed fruit during cold storage at 0 to 1 °C for 2 months. Antioxidant and some phenolic compounds were higher than those of control fruit.
The Terravent TM soil injection device (Pinnacle Concepts, Ltd., Cornwall, UK) uses compressed ni... more The Terravent TM soil injection device (Pinnacle Concepts, Ltd., Cornwall, UK) uses compressed nitrogen gas to fracture compacted soil and permits the subsequent injection of liquid amendments. In the current study, we measured fine root growth and architecture in soil that had received one of four treatments: 1) Terravent injections, 2) Terravent injections followed by liquid amendment (MycorTree Injectable; PHC, Inc., Pittsburgh, PA, U.S.), 3) addition of amendment only, and 4) an untreated control. The experiment was conducted on ten red maples (Acer rubrum) growing on a moderately compacted urban clay soil next to a busy road on the Clemson University campus. Treatments were applied in April 2002. Seven weeks later, soil cores were pulled from locations adjacent to the injection sites, and fine roots (less than 2 mm [0.08 in] in diameter) from each core were washed free of soil. A variety of root parameters were measured, including length, surface area, diameter distribution, and mass. Terravent treatment had no effect on any root parameters measured. Application of MycorTree was associated with small, statistically significant reductions in root diameter, root mass density (mg root/cm 3 soil), and root surface area density (cm 2 root/cm 3 soil).
We investigated seasonal dynamics of mycorrhizal colonization in response to precipitation in a M... more We investigated seasonal dynamics of mycorrhizal colonization in response to precipitation in a Mojave Desert Larrea tridentata-Ambrosia dumosa shrub community as part of the overall Nevada Desert FACE (Free-Air CO2 Enrichment) Facility (NDFF) with the goal to understand carbon flow through desert ecosystems in the context of increased carbon availability associated with climate change. Arbuscular mycorrhizal (AM) fungal colonization of fine roots varied with season and with species in the co-dominant shrubs L. tridentata and A. dumosa at a site adjacent to the NDFF. We collected fine roots (<1.0 mm diameter) at monthly intervals throughout 2001 and from October 2002 to September 2003 to quantify percent colonization via the line intercept method in cleared roots stained with trypan blue to visualize fungi. Colonization was highest in fall, increased throughout spring, and decreased during summer drought periods. Increases in colonization during summer and fall reflected increases in precipitation. Although peak precipitation occurred in spring, mycorrhizal colonization was not correspondingly high, suggesting that fine root initiation and growth, early season shoot growth, and flowering may have reduced carbon availability to the fungus.
... March 2009 Performance of Mycorrhizal Products Marketed for Woody Landscape Plants1 P. Eric W... more ... March 2009 Performance of Mycorrhizal Products Marketed for Woody Landscape Plants1 P. Eric Wiseman2, Kristen H. Colvin3, and Christina E. Wells4 Department of Horticulture, Clemson University, Clemson, SC 29634 Abstract ... 65.9 g/L 1, 2, 3, 5 Santa Maria, CA and one ...
Page 1. 70 J. Environ. Hort. 27(2):70–79. June 2009 Arbuscular Mycorrhizal Inoculation Affects Ro... more Page 1. 70 J. Environ. Hort. 27(2):70–79. June 2009 Arbuscular Mycorrhizal Inoculation Affects Root Development of Acer and Magnolia Species1 P. Eric Wiseman2 and Christina E. Wells3 Department of Forestry, Virginia Tech ...
Machine Vision and Applications
An approach to automate the extraction and measurement of roots in minirhizotron images is presen... more An approach to automate the extraction and measurement of roots in minirhizotron images is presented. Two-dimensional matched filtering is followed by local entropy thresholding to produce binarized images from which roots are detected. After applying a root classifier to discriminate fine roots from unwanted background objects, a root labeling method is implemented to identify each root in the image. Once a root is detected, its length and diameter are measured using Dijkstra's algorithm for obtaining the central curve and the Kimura-Kikuchi-Yamasaki method for measuring the length of the digitized path. Experimental results from a collection of peach (Prunus persica) root images demonstrate the effectiveness of the approach.
Journal of nematology
Desiccation tolerance plays an important role in the overwinter survival of the foliar nematode A... more Desiccation tolerance plays an important role in the overwinter survival of the foliar nematode Aphelenchoides fragariae. Survival rates of A. fragariae were compared with those of the anhydrobiotic soil-dwelling nematode Aphelenchus avenae after desiccation (90% RH), cold (4°C) and osmotic (500 mM sucrose) stress treatments. A. fragariae formed aggregates during desiccation and showed higher survival rates than A. avenae under desiccation and osmotic stress. Analysis of transcripts with Illumina RNA-seq indicated that glutaredoxin and other antioxidant-related genes were up-regulated under desiccation stress. Quantitative RT-PCR demonstrated 2.8 fold and 1.3 fold up-regulation of a glutaredoxin gene under desiccated and osmotic stress, respectively, suggesting the participation of antioxidant mechanisms in desiccation tolerance of A. fragariae.
Http Dx Doi Org 10 1080 01904160903470497, Jan 8, 2010
The relationship between root age and root physiology is poorly understood, despite its importanc... more The relationship between root age and root physiology is poorly understood, despite its importance for nutrient absorption. In peaches, roots are white when they first appear and then become brown with age, which corresponds to a number of physiological changes. We related root ...
PLOS ONE, 2015
Low-cost, high throughput genotyping methods are crucial to marker discovery and marker-assisted ... more Low-cost, high throughput genotyping methods are crucial to marker discovery and marker-assisted breeding efforts, but have not been available for many &amp;amp;amp;amp;amp;#39;specialty crops&amp;amp;amp;amp;amp;#39; such as fruit and nut trees. Here we apply the Genotyping-By-Sequencing (GBS) method developed for cereals to the discovery of single nucleotide polymorphisms (SNPs) in a peach F2 mapping population. Peach is a genetic and genomic model within the Rosaceae and will provide a template for the use of this method with other members of this family. Our F2 mapping population of 57 genotypes segregates for bloom time (BD) and chilling requirement (CR) and we have extensively phenotyped this population. The population derives from a selfed F1 progeny of a cross between &amp;amp;amp;amp;amp;#39;Hakuho&amp;amp;amp;amp;amp;#39; (high CR) and &amp;amp;amp;amp;amp;#39;UFGold&amp;amp;amp;amp;amp;#39; (low CR). We were able to successfully employ GBS and the TASSEL GBS pipeline without modification of the original methodology using the ApeKI restriction enzyme and multiplexing at an equivalent of 96 samples per Illumina HiSeq 2000 lane. We obtained hundreds of SNP markers which were then used to construct a genetic linkage map and identify quantitative trait loci (QTL) for BD and CR.
VI International Peach Symposium, 2006
The foliar nematode Aphelenchoides fragariae (Aphelenchida: Aphelenchidae) is an endo- and ectopa... more The foliar nematode Aphelenchoides fragariae (Aphelenchida: Aphelenchidae) is an endo- and ectoparasite that feeds on aerial parts of over 250 plant species from 47 families. It is a common and economically-damaging pest of nursery-grown crops including ferns, foliage and flowering plants, and herbaceous and woody perennials. We used Illumina HiSeq 2000 technology and the Trinity de novo assembler (trinityrnaseq.sourceforge.net/) to produce a transcriptome of A. fragariae from four growth conditions (fungal-fed, plant-fed, diet-changed, and desiccated). High throughput sequencing generated 43 million reads with average length of 100-bp. Assembly of the pooled read set generated 95,930 contigs, corresponding to 50,686 unigenes (mean length = 605 bp) with 45,244 alternate splice variants. Fifty-two percent of the unigenes (26,389) had homology to known genes or proteins in the NCBI non-redundant database, and 20,558 were assigned GO terms based on these homologies by Blast2Go software...
Journal of Plant Nutrition, 2010
The relationship between root age and root physiology is poorly understood, despite its importanc... more The relationship between root age and root physiology is poorly understood, despite its importance for nutrient absorption. In peaches, roots are white when they first appear and then become brown with age, which corresponds to a number of physiological changes. We related root ...
Douglas G. Bielenberg: A.
Germanium has been reported as a mineral element affecting plant cell metabolism. Many trials to ... more Germanium has been reported as a mineral element affecting plant cell metabolism. Many trials to supply germanium to fruit have been carried out since tests have confi rmed germanium's role as a medical substance. Supplying germanium to orchards by soil and foliar application was not effective because of loss from rainfall. Also, tree injection with germanium solution required the insertion of a tube to the tree xylem at each injection site. In order to increase germanium absorption by fruit, this study carried out the postharvest dipping of fruit into germanium solution. 'Niitaka' pear ( Pyrus pyrifolia ) fruit was treated with two types of germanium, GeO (inorganic type) and Ge-132 (organic type), in a concentration of 50 mg·L -1 just after harvest in early Oct. 2004. Flesh browning after peeling the fruit was delayed by germanium treatment, and polyphenoloxidase (PPO) activities were lowered. Postharvest potentials were maintained at high levels for fruit fi rmness, physiological disorders, and decayed fruit during cold storage at 0 to 1 °C for 2 months. Antioxidant and some phenolic compounds were higher than those of control fruit.
The Terravent TM soil injection device (Pinnacle Concepts, Ltd., Cornwall, UK) uses compressed ni... more The Terravent TM soil injection device (Pinnacle Concepts, Ltd., Cornwall, UK) uses compressed nitrogen gas to fracture compacted soil and permits the subsequent injection of liquid amendments. In the current study, we measured fine root growth and architecture in soil that had received one of four treatments: 1) Terravent injections, 2) Terravent injections followed by liquid amendment (MycorTree Injectable; PHC, Inc., Pittsburgh, PA, U.S.), 3) addition of amendment only, and 4) an untreated control. The experiment was conducted on ten red maples (Acer rubrum) growing on a moderately compacted urban clay soil next to a busy road on the Clemson University campus. Treatments were applied in April 2002. Seven weeks later, soil cores were pulled from locations adjacent to the injection sites, and fine roots (less than 2 mm [0.08 in] in diameter) from each core were washed free of soil. A variety of root parameters were measured, including length, surface area, diameter distribution, and mass. Terravent treatment had no effect on any root parameters measured. Application of MycorTree was associated with small, statistically significant reductions in root diameter, root mass density (mg root/cm 3 soil), and root surface area density (cm 2 root/cm 3 soil).
We investigated seasonal dynamics of mycorrhizal colonization in response to precipitation in a M... more We investigated seasonal dynamics of mycorrhizal colonization in response to precipitation in a Mojave Desert Larrea tridentata-Ambrosia dumosa shrub community as part of the overall Nevada Desert FACE (Free-Air CO2 Enrichment) Facility (NDFF) with the goal to understand carbon flow through desert ecosystems in the context of increased carbon availability associated with climate change. Arbuscular mycorrhizal (AM) fungal colonization of fine roots varied with season and with species in the co-dominant shrubs L. tridentata and A. dumosa at a site adjacent to the NDFF. We collected fine roots (<1.0 mm diameter) at monthly intervals throughout 2001 and from October 2002 to September 2003 to quantify percent colonization via the line intercept method in cleared roots stained with trypan blue to visualize fungi. Colonization was highest in fall, increased throughout spring, and decreased during summer drought periods. Increases in colonization during summer and fall reflected increases in precipitation. Although peak precipitation occurred in spring, mycorrhizal colonization was not correspondingly high, suggesting that fine root initiation and growth, early season shoot growth, and flowering may have reduced carbon availability to the fungus.
... March 2009 Performance of Mycorrhizal Products Marketed for Woody Landscape Plants1 P. Eric W... more ... March 2009 Performance of Mycorrhizal Products Marketed for Woody Landscape Plants1 P. Eric Wiseman2, Kristen H. Colvin3, and Christina E. Wells4 Department of Horticulture, Clemson University, Clemson, SC 29634 Abstract ... 65.9 g/L 1, 2, 3, 5 Santa Maria, CA and one ...
Page 1. 70 J. Environ. Hort. 27(2):70–79. June 2009 Arbuscular Mycorrhizal Inoculation Affects Ro... more Page 1. 70 J. Environ. Hort. 27(2):70–79. June 2009 Arbuscular Mycorrhizal Inoculation Affects Root Development of Acer and Magnolia Species1 P. Eric Wiseman2 and Christina E. Wells3 Department of Forestry, Virginia Tech ...
Machine Vision and Applications
An approach to automate the extraction and measurement of roots in minirhizotron images is presen... more An approach to automate the extraction and measurement of roots in minirhizotron images is presented. Two-dimensional matched filtering is followed by local entropy thresholding to produce binarized images from which roots are detected. After applying a root classifier to discriminate fine roots from unwanted background objects, a root labeling method is implemented to identify each root in the image. Once a root is detected, its length and diameter are measured using Dijkstra's algorithm for obtaining the central curve and the Kimura-Kikuchi-Yamasaki method for measuring the length of the digitized path. Experimental results from a collection of peach (Prunus persica) root images demonstrate the effectiveness of the approach.
Journal of nematology
Desiccation tolerance plays an important role in the overwinter survival of the foliar nematode A... more Desiccation tolerance plays an important role in the overwinter survival of the foliar nematode Aphelenchoides fragariae. Survival rates of A. fragariae were compared with those of the anhydrobiotic soil-dwelling nematode Aphelenchus avenae after desiccation (90% RH), cold (4°C) and osmotic (500 mM sucrose) stress treatments. A. fragariae formed aggregates during desiccation and showed higher survival rates than A. avenae under desiccation and osmotic stress. Analysis of transcripts with Illumina RNA-seq indicated that glutaredoxin and other antioxidant-related genes were up-regulated under desiccation stress. Quantitative RT-PCR demonstrated 2.8 fold and 1.3 fold up-regulation of a glutaredoxin gene under desiccated and osmotic stress, respectively, suggesting the participation of antioxidant mechanisms in desiccation tolerance of A. fragariae.