http://repositorio.ufc.br/handle/riufc/336 2026-04-08T09:19:17Z http://repositorio.ufc.br/handle/riufc/85601 Título: Papel funcional da família de enzimas glicolato oxidase (GOX) e catalase (CAT) em feijão-caupi (Vigna unguiculata [L.] Walp.) na resposta ao Cowpea Severe Mosaic Virus Autor(es): Bezerra, Victor Breno Faustino Abstract: With the increase in food shortages and nutritional deficiencies, the choice of alternative crops with relevant characteristics is important. Vigna unguiculata L. is therefore a crop of great interest. However, cowpeas are still susceptible to some pathogens, such as the CowPea Severe Mosaic Virus (CPSMV). Under adverse conditions, such as infection by pathogens, one of the initial mechanisms for the stress response involves the production of reactive oxygen species. One of these molecules is hydrogen peroxide, which has its highest production rate related to Glycolate Oxidase (GOX), an enzyme in the photorespiration process, but like all reactive species, its production and consumption must be finely balanced, so there is the peroxisomal enzyme Catalase (CAT), responsible for this control during a stress phenomenon. The aim of this study was therefore to analyse the expression of GOX and CAT gene copies, at transcript and activity level, in response to CPSMV. To this end, the plant specimens were inoculated with CPSMV at three time points (16 hours, 48 hours and 144 hours). Analyses of catalase enzyme activity showed differences between the cultivars only in the initial hours (16h), in the control conditions of inoculated Pitiúba and Mock, possibly related to the initial response to the pathogen. In addition, analyses using DAB (3,3'-Diaminobenzidine) staining, MDA (Malonaldehyde) and peroxide content were used to determine the degree of oxidative stress, again with differences only between Pitiúba Mock and inoculated at 16 and 48 hours. In addition, the expression data showed differences mainly in the VuGOX1 gene in the Macaíbo cultivar, whose expression was induced during infection compared to the Mock. While VuGOX2 was the gene with the highest abundance at transcript level, showing differences between the cultivars at times of 16 and 144h, with reduced expression in inoculated Pitiúba compared to Mock 144h. Analysis of cis-elements showed regions that corroborate points raised in the discussion, mainly related to the pathogen response route and the synthesis of salicylic acid (SA). Thus, it is hoped that the results found will help breeding programmes and understanding of the resistance phenomenon. Tipo: Dissertação 2025-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85557 Título: Plasticidade de cajueiros à baixa disponibilidade hídrica no solo: mecanismos fisiológicos, metabólicos e epigenéticos Autor(es): Costa, Igor Rafael Sousa Abstract: The cashew tree (Anacardium occidentale L.) is a highly relevant species for the Brazilian semi-arid region, which it develops under environmental conditions characterized by a combination of abiotic stresses, such as high irradiance, salinity, water deficit, and high temperatures. Adaptation to this environment involves physiological and molecular mechanisms that regulate acclimation to environmental stress. This thesis investigated the processes that support tolerance and the ability to adjust to water deficit in the cashew tree, integrating different biological levels to identify functional patterns associated with adaptation. In the first chapter, physiological, biochemical, metabolic, and molecular responses were evaluated in two contrasting cashew genotypes subjected to successive cycles of water deficit followed by rehydration. The BRS 226 genotype showed greater osmotic stability during stress, more efficient photosynthetic recovery, and greater functional adjustment capacity after repeated drought exposures. The regulation of the redox state and the progressive activation of the antioxidant system indicated physiological adjustment to recurrent stress, accompanied by extensive metabolic reorganization, with modulation of compounds associated with energy metabolism and cellular adaptation. In contrast, the CCP 09 genotype showed more restricted physiological and metabolic responses, with less recovery capacity after successive stress cycles. The differential modulation of the expression of genes associated with the stress response and the activation of markers re ated to DNA methylation during recovery suggest the participation of epigenetic mechanisms in the physiological reorganization induced by drought cycles. Taken together, the results indicate that the differential tolerance between genotypes is associated with the coordination between physiological, metabolic, and molecular adjustments in response to recurrent water stress. The second chapter investigated the epigenetic dynamics associated with a single water deficit event followed by recovery in cashew seedlings, using enzymatic sequencing of DNA methylation. Although the overall methylation profile remained relatively stable across water conditions, extensive local alterations were detected throughout the genome, indicating epigenetic reorganization associated with the plant's physiological state. These modifications were related to distinct regulatory and metabolic processes between stress and recovery phases, suggesting that DNA methylation participates in the functional modulation of the water response. The observed epigenetic variations accompanied changes in photosynthetic performance and the expression of marker genes, highlighting an association between epigenetic modulation and physiological adjustments to water deficit. In an integrated manner, the results demonstrate that the cashew tree's response to water deficit involves coordination between physiological, metabolic, and epigenetic processes that contribute to functional adjustments of metabolism and the photosynthetic apparatus during stress and recovery. These findings broaden the understanding of the regulatory mechanisms associated with the water response in tropical perennial species and provide a basis for the development of genetic improvement strategies and adaptive management under scenarios of greater climate variability. Tipo: Tese 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85389 Título: Atividade antimicrobiana do óleo essencial de Croton pluriglandulosus Carn. (Euphorbiaceae) contra microrganismos de interesse clínico Autor(es): Carvalho, Rayara Joice Paulino Abstract: Fungal and bacterial infections remain significant causes of morbidity and mortality, exacerbated by increasing resistance to conventional antimicrobials. Yeasts of the genus Candida cause infections in both immunocompetent and immunocompromised individuals, while associated pathogenic bacteria are the primary cause of urinary, respiratory, and systemic infections, often resistant to multiple classes of antimicrobials. In this context, plant-derived essential oils stand out as promising therapeutic alternatives due to their antifungal and antibacterial properties. Their antimicrobial activity is mainly related to the destabilization of the plasma membrane and interference in essential metabolic processes, contributing to the fight against microbial resistance. This study aims to evaluate the antimicrobial activity and mechanisms of action of the essential oil (EO) extracted from the leaves of Croton pluriglandulosus Carn.-Torres & Riina (CpEO) on human pathogenic microorganisms in planktonic lifestyles and biofilms. The results demonstrated that the essential oil of Croton pluriglandulosus has 26 different metabolites, with elemicin (25.77%), bicyclogermacrene (9.37%), caryophyllene (8.99%), 1,3,5-trimethoxybenzene (6.86%), and hedicariol (6.21%) being the major compounds. The oil, at a concentration of 50 μg mL−1 , was able to inhibit the planktonic growth of C. krusei (89.3%) and C. parapsilosis (80.70%). Furthermore, biofilm formation was initiated in 85.5% of C. krusei and 77.9% of C. parapsilosis. There was no reduction in the biomass of the pre-formed biofilm. The prevention data were not excessive for the species C. albicans and all tested bacterial species (B. subtilis, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus e Salmonella enterica). Fluorescence microscopy analyses showed that the oil ages, causing cell membrane damage, cell death, and inducing the production of reactive oxygen species (ROS). Electron microscopy images showed high-resolution morphological damage to the cells upon contact with the oil. Furthermore, the oil did not cause hemolysis in human erythrocytes at the concentrated level. The data obtained offer a future alternative for obtaining drugs and active compounds to be used by the clinical sector for microbiological control purposes. Tipo: Dissertação 2023-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85351 Título: Abordagem ômica integrada na investigação da aclimatação ao estresse salino induzida pela ativação do retículo endoplasmático em feijão-caupi (Vigna unguiculata [L.] Walp) Autor(es): Cavalcante, Francisco Lucas Pacheco Abstract: Salinity represents one of the main limiting factors for agricultural productivity, affecting ionic homeostasis, redox balance, metabolism, and plant growth. Although the endoplasmic reticulum (ER) is recognized as an important hub for integrating cellular signals under stress conditions, the mechanisms by which its activation can modulate salt tolerance in cowpea (Vigna unguiculata [L.] Walp.) remain incompletely understood. This thesis investigated whether the controlled stimulation of adaptive endoplasmic reticulum signaling, through transient activation of the unfolded protein response (UPR) induced by tunicamycin (TM), could function as a priming mechanism, increasing the efficiency of acclimation to salinity. Foliar application of TM was selected to induce systemic ER signaling without directly altering ion uptake by roots, allowing the controlled activation of adaptive pathways prior to salt exposure. An integrative and temporal approach was employed, combining physiological analyses, Na+ and K+ quantification, hydrogen peroxide (H2O2) determination, qPCR-based gene expression analysis of unfolded protein response (UPR) markers and ion transporters, as well as metabolomic, lipidomic, and quantitative proteomic analyses in leaves. The results demonstrated that TM priming significantly attenuated the deleterious effects of NaCl, promoting improved photosynthetic performance and enhanced plant growth. A reduction in Na+ accumulation in the shoot, greater K+ retention, and increased ionic sequestration in roots were observed, indicating improved ionic homeostasis. TM application induced a rapid and transient ER stress response, characterized by an initial increase in H2O2 and early expression of UPR-related genes, with a return to basal levels within 24 hours. Under salinity, plants previously treated with TM exhibited lower H2O2 accumulation, earlier and more efficient activation of pathways associated with ER signaling and sodium transport, as well as reduced expression of chaperones and Na+ transporters. Proteomic analysis revealed that salinity promoted broad metabolic repression, including reductions in enzymes of the Calvin cycle and glycolysis (GAPDH, triose phosphate isomerase) and in ribosomal proteins, whereas TM priming attenuated this suppression and promoted selective reinforcement of the translational machinery and proteins associated with stress adaptation. Metabolomic and lipidomic profiles indicated enhanced osmotic adjustment and membrane remodeling, reinforcing cellular stability under stress conditions. It is concluded that transient ER activation acts as a physiological preconditioning mechanism, coordinating redox regulation, proteostasis, ionic homeostasis, and metabolic reprogramming. These findings expand the understanding of the ER as a regulatory hub in plant adaptation to salt stress and highlight promising molecular targets for breeding strategies aimed at increasing cowpea resilience in salinized environments. Tipo: Tese 2026-01-01T00:00:00Z