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Browsing by Author "Koehler, Gage"
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Item Integrative "omic" analysis reveals distinctive cold responses in leaves and roots of strawberry, Fragaria × ananassa 'Korona'(Frontiers Media SA, 2015) Koehler, Gage; Rohloff, Jens; Wilson, Robert C.; Kopka, Joachim; Erban, Alexander; Winge, Per; Bones, Atle M.; Davik, Jahn; Alsheikh, Muath K.; Randall, Stephen K.; Department of Biology, School of ScienceTo assess underlying metabolic processes and regulatory mechanisms during cold exposure of strawberry, integrative "omic" approaches were applied to Fragaria × ananassa Duch. 'Korona.' Both root and leaf tissues were examined for responses to the cold acclimation processes. Levels of metabolites, proteins, and transcripts in tissues from plants grown at 18°C were compared to those following 1-10 days of cold (2°C) exposure. When leaves and roots were subjected to GC/TOF-MS-based metabolite profiling, about 160 compounds comprising mostly structurally annotated primary and secondary metabolites, were found. Overall, 'Korona' showed a modest increase of protective metabolites such as amino acids (aspartic acid, leucine, isoleucine, and valine), pentoses, phosphorylated and non-phosphorylated hexoses, and distinct compounds of the raffinose pathway (galactinol and raffinose). Distinctive responses were observed in roots and leaves. By 2DE proteomics a total of 845 spots were observed in leaves; 4.6% changed significantly in response to cold. Twenty-one proteins were identified, many of which were associated with general metabolism or photosynthesis. Transcript levels in leaves were determined by microarray, where dozens of cold associated transcripts were quantitatively characterized, and levels of several potential key contributors (e.g., the dehydrin COR47 and GADb) to cold tolerance were confirmed by qRT-PCR. Cold responses are placed within the existing knowledge base of low temperature-induced changes in plants, allowing an evaluation of the uniqueness or generality of Fragaria responses in photosynthetic tissues. Overall, the cold response characteristics of 'Korona' are consistent with a moderately cold tolerant plant.Item Overwintering Survival of Strawberry (Fragaria x ananassa): Proteins Associated with Low Temperature Stress Tolerance during Cold Acclimation in Cultivars(2011-12) Koehler, Gage; Staiger, Christopher J.; Randall, Stephen Karl, 1953-; Watson, John C., 1953-; Blazer-Yost, Bonnie; Hasegawa, Paul M.Winter survival is variable among commercially grown strawberry (Fragaria x ananassa) cultivars. The main objectives of this study were to evaluate the molecular basis that contribute to this difference in strawberry cultivars and to identify potential biomarkers that can be used to facilitate the development of new strawberry cultivars with improved overwintering hardiness. With these goals in mind, the freezing tolerance was examined for four cultivars, ‘Jonsok’, ‘Senga Sengana’, ‘Elsanta’, and ‘Frida’ (listed from most to least freezing tolerant based on survival from physiological freezing experiments) and the protein expression was investigated in the overwintering relevant crown structure of strawberry. Biomarker selection was based on comparing the protein profiles from the most cold-tolerant cultivar, ‘Jonsok’ with the least cold-tolerant cultivar ‘Frida’ in a comprehensive investigation using two label-free global proteomic methods, shotgun and two dimensional electrophoresis, with support from univariate and multivariate analysis. A total of 143 proteins from shotgun and 64 proteins from 2DE analysis were identified as significantly differentially expressed between ‘Jonsok’ and ‘Frida’ at one or more time points during the cold treatment (0, 2, and 42 days at 2 ºC). These proteins included molecular chaperones, antioxidants/detoxifying enzymes, metabolic enzymes, pathogenesis related proteins and flavonoid pathway proteins. The proteins that contributed to the greatest differences between ‘Jonsok’ and ‘Frida’ are candidates for biomarker development. The novel and significant aspects of this work include the first crown proteome 2DE map with general characteristics of the strawberry crown proteome, a list of potential biomarkers to facilitate the development of new strawberry cultivars with improved cold stress tolerance.