Browsing by Author "Lopez-Bautista, Juan"
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Item Identification and Characterization of Arabidopsis Toxicos En Levadura 12: a Gene Involved in Chitin-Elicitor-Triggered Immunity and Salt Tolerance(University of Alabama Libraries, 2022) Kong, Feng; Ramonell, Katrina; University of Alabama TuscaloosaPlants have evolved complex systems to respond to changes in environmental conditions. Understanding the underlying signal transduction events in the plant response is crucial for greater insight into plant-environment interactions and to establish transgenic strategies to improve stress tolerance in crops. The aim of this dissertation was to identify and characterize the Arabidopsis Toxicos en Levadura 12 (ATL12) gene and explore the role of ATL12 in defense against powdery mildew and in salt stress tolerance. ATL12 encodes a conserved C3HC4 RING-type protein that has E3 ubiquitin ligase activity. Subcellular co-localization assays indicate that ATL12 localizes to the plasma membrane. Compared to Columbia wild-type, mutants in atl12 are more susceptible to fungal infection, whereas overexpression of ATL12 increased resistance to the fungus. Mutants of atl12 display a decreased seed germination rate, a reduction in root length growth, and a higher survival rate under high salt conditions. QRT-PCR studies showed that ATL12 is highly induced by chitin at early time points and its expression is linked to the activation of the MAPK cascade, pointing to the possible role of ATL12 in the early hypersensitive response and the local plant response to fungal pathogens. Additionally, the expression of respiratory burst oxidase homolog protein D/F was also found to decrease in the atl12 mutant, while the expression of ATL12 was not affected in atrbohd and atrbohf mutants. Together these data suggest that chitin-induced ATL12 expression is also linked to NADPH oxidase AtRBOHD/F-driven ROS production. ATL12 is also salt-inducible, and its expression is up-regulated at late stages in response to NaCl stress. Over-expression of ATL12 increases the expression of the salt stress-associated genes SOS1 and SOS2, and the ABA-dependent genes RD29B and RAB18. Further the expression of ATL12 was up-regulated after treatment with salicylic acid and jasmonic acid, indicating a possible role for ATL12 in plant hormone-mediated defense responses. In summary, these results indicate that ATL12 is involved in crosstalk between the SA-, JA-, chitin-induced MAPK, and NADPH oxidase-mediated defense responses against fungal pathogens and that it modulates salt stress responses through an ABA-dependent pathway and intensifying the ROS response in Arabidopsis thaliana.Item Site-Specific Variability in the Chemical Diversity of the Antarctic Red Alga Plocamium cartilagineum(MDPI, 2013) Young, Ryan M.; von Salm, Jacqueline L.; Amsler, Margaret O.; Lopez-Bautista, Juan; Amsler, Charles D.; McClintock, James B.; Baker, Bill J.; University of South Florida; University of Alabama Birmingham; University of Alabama TuscaloosaPlocamium cartilagineum is a common red alga on the benthos of Antarctica and can be a dominant understory species along the western Antarctic Peninsula. Algae from this region have been studied chemically, and like "P. cartilagineum" from other worldwide locations where it is common, it is rich in halogenated monoterpenes, some of which have been implicated as feeding deterrents toward sympatric algal predators. Secondary metabolites are highly variable in this alga, both qualitatively and quantitatively, leading us to probe individual plants to track the possible link of variability to genetic or other factors. Using cox1 and rbcL gene sequencing, we find that the Antarctic alga divides into two closely related phylogroups, but not species, each of which is further divided into one of five chemogroups. The chemogroups themselves, defined on the basis of Bray-Curtis similarity profiling of GC/QqQ chromatographic analyses, are largely site specific within a 10 km(2) area. Thus, on the limited geographical range of this analysis, P. cartilagineum displays only modest genetic radiation, but its secondary metabolome was found to have experienced more extensive radiation. Such metabogenomic divergence demonstrated on the larger geographical scale of the Antarctic Peninsula, or perhaps even continent-wide, may contribute to the discovery of cryptic speciation.Item Unicellular Eukaryotic Community Response to Temperature and Salinity Variation in Mesocosm Experiments(Frontiers, 2018) Stefanidou, Natassa; Genitsaris, Savvas; Lopez-Bautista, Juan; Sommer, Ulrich; Moustaka-Gouni, Maria; Aristotle University of Thessaloniki; University of Alabama Tuscaloosa; Helmholtz Association; GEOMAR Helmholtz Center for Ocean Research KielClimate change has profound impacts on marine biodiversity and biodiversity changes in turn might affect the community sensitivity to impacts of abiotic changes. We used mesocosm experiments and Next Generation Sequencing to study the response of the natural Baltic and Mediterranean unicellular eukaryotic plankton communities (control and +6 degrees C heat shock) to subsequent salinity changes (-5 psu, +5 psu). The impact on Operational Taxonomic Unit (OTU) richness, taxonomic and functional composition and rRNA:rDNA ratios were examined. Our results showed that heat shock leads to lower OTU richness (21% fewer OTUs in the Baltic and 14% fewer in the Mediterranean) and a shift in composition toward pico- and nanophytoplankton and heterotrophic related OTUs. Heat shock also leads to increased rRNA:rDNA ratios for pico- and micrograzers. Less than 18% of shared OTUs were found among the different salinities indicating the crucial role of salinity in shaping communities. The response of rRNA:rDNA ratios varied highly after salinity changes. In both experiments the diversity decrease brought about by heat shock influenced the sensitivity to salinity changes. The heat shock either decreased or increased the sensitivity of the remaining community, depending on whether it removed the more salinity-sensitive or the salinity-tolerant taxa.