Browsing by Author "Shuman, Joel L."

Now showing 1 - 4 of 4
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    Actigard May Reduce Disease in Strawberry
    Shuman, Joel L. (Virginia Cooperative Extension, 2005-09-01)
    Discusses the results of a two year study conducted to evaluate Actigard for its ability to control anthracnose on strawberry in greenhouse at Virginia Tech and field studies at Kentland Farm in Whitethorne, VA beginning in 2002.
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    Identification Of Candidate Genes For Self-Compatibility In A Diploid Population Of Potato Derived From Parents Used In Genome Sequencing
    Arnold, Brenda Elaine (Virginia Tech, 2013-10-03)
    Gametophytic self-incompatibility limits the ability to derive inbred lines of potato through self-pollination and is prevalent in diploid potato. Within a population of F1 hybrids between two genotypes used in potato genome sequencing, we observed fruit set on many greenhouse-grown plants. Subsequently, after controlled self-pollinations, we confirmed fruit set in 32 of 103 F1 plants. Our goal was to identify genes responsible for self-compatibility in this population and to advance selfed progeny to develop highly homozygous inbred lines. The F1 population was genotyped using a single nucleotide polymorphism (SNP) array. Polymorphic and robust SNPs were analyzed by Fisher\'s Exact Test to identify allelic states segregating with the self-compatible phenotype. Filtering 1966 SNPs to retain only those with p-values less than 0.0001 yielded 95 highly significant SNPs, with all SNPs on anchored scaffolds located on chromosome 12. Candidate genes encoding for multiple notable proteins including an S-protein homologue were identified near highly significant SNPs on the Potato Genome Browser. Seeds obtained after self-pollination of self-compatible individuals were used to advance the population for three generations. SNP chip genotyping of the S3 generation revealed entirely different SNPs segregating for self-compatibility on nine different chromosomes. Comparison of the allelic state of SNPs in the F1 and S3 generations revealed a heterozygosity reduction by 80%, with fixation of many SNPs including those surrounding the S-protein homologue. We conclude that the genes responsible for segregation of self-compatibility in the S3 generation are different from those in the F1 generation.
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    Improved regeneration and Agrobacterium-mediated transformation of wild strawberry (Fragaria vesca L.)
    Wadl, Phillip A. (Virginia Tech, 2005-12-14)
    The Rosaceae contains many important commercially grown fruit crops. No comprehensive genomics platform is currently under development for fruit crops, giving functional genomics studies with wild strawberry (Fragaria vesca L.) the potential of identifying genes important in fruit crops. Fragaria vesca has a small genome size compared to the cultivated strawberry, Fragaria à ananassa Duch. (164 vs. 600 Mbp per 1C nucleus). This feature, in addition to a short life cycle (12-16 weeks) and small plant size make F. vesca a good candidate for a model plant for genetic and molecular studies. The specific objective of this work was to develop an efficient high-throughput Agrobacterium-mediated transformation protocol to generate an insertional mutant population to support the justification of F. vesca as a model organism for rosaceous crops. The transformation techniques described by Alsheikh et al. (2002) and Oosumi et al. (2005) were modified and applied to a range of germplasm obtained from the USDA National Germplasm Repository. We found that the modifications made to the Alsheikh protocol were unsuccessful when applied to our germplasm. With the Oosumi et al. (2005) protocol, transformation efficiencies ranging from 11 to 100% were obtained for two accessions when explants were exposed to varying durations on TDZ containing medium during shoot regeneration. The transformation efficiency was given as the mean number of GFP+ plants obtained per primary explant cultured. Multiplex PCR, for amplification of the hptII and GFP genes, was performed on a random sample of GFP+ plants to verify insertion of the T-DNA. The statistical power of our experiment was insufficient to detect treatment effect but based on our findings the transformation efficiencies were high enough to justify PI 551572 for use in the high throughput transformations that are required to generate a population of insertional mutants large enough for gene discovery in F. vesca.
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    Quantitative characterization of hemozoin in Plasmodium berghei and vivax
    Pisciotta, John M.; Scholl, Peter F.; Shuman, Joel L.; Shualev, Vladimir; Sullivan, David J. (Elsevier, 2017-04-01)
    The incidence and global distribution of chloroquine resistant (CR) Plasmodium vivax infection has increased since emerging in 1989. The mechanism of resistance in CR P. vivax has not been defined. The resistance likely relates to the formation and disposition of hemozoin as chloroquine's primary mechanism of action involves disruption of hemozoin formation. CR P. berghei strains, like CR P. vivax strains, are confined to reticulocyte host cells and reportedly they do not accumulate appreciable intraerythrocytic hemozoin. Reports comparing hemozoin production between P. vivax strains and CR to chloroquine sensitive (CS) P. berghei are absent. Here we compare in vivo patterns of hemozoin formation and distribution in blood, spleen and liver tissue of male Swiss mice infected with CS or CR P. berghei not treated with chloroquine and CR P. berghei also treated with chloroquine. Light microscopy, laser desorption mass spectrometry and a colorimetric hemozoin assay detect trace hemozoin in the blood of CR P. berghei infected mice but significant hemozoin accumulation in liver and spleen tissue. Field emission in lens scanning electron microscopy reveals CR P. berghei hemozoin crystals are morphologically smaller but similar to those formed by CS parasites. CR P. berghei produces approximately five-fold less total hemozoin than CS strain. Lipid analysis of CS and CR P. berghei sucrose gradient purified bloodstage hemozoin indicates a similar lipid environment around the isolated hemozoin, predominately monopalmitic glycerol and monostearic glycerol. In contrast to CR and CS P. berghei, colorimetric hemozoin analysis of P. vivax strains indicates similar amounts of hemozoin are produced despite differing chloroquine sensitivities. These results suggest CR P. berghei forms significant hemozoin which accumulates in liver and spleen tissues and that the P. vivax chloroquine resistance mechanism differs from P. berghei.