Orientador: Douglas Silva Domingues / Banca: Danilo Centeno / Banca: Monalisa Sampaio Carneiro / Resumo: A aplicação energética dos subprodutos da cana-de-açúcar faz dessa cultura uma das líderes em investimentos do agronegócio internacional. Para suprir a demanda mundial e expandir o setor sucroenergético, estratégias de engenharia genética que possam gerar plantas transgênicas mais tolerantes a estreses bióticos e abióticos podem ser uma alternativa para ganhos de produtividade. Um dos mecanismos mais utilizados em plantas para minimizar os efeitos causados por estresses é o acúmulo de solutos. Entre eles, pode ser destacada a família de oligossacarídeos da rafinose (RFOs). Ela é formada a partir da adição sucessiva de radicais galactosil a uma molécula de sacarose, em reação catalisada pelas enzimas galactinol sintase (GolS), rafinose sintase e estaquiose sintase. A GolS é considerada o passo-chave de regulação da síntese de RFOs em plantas modelo. Embora a compreensão das etapas moleculares da produção de RFOs e sua modulação por estresses abióticos tenham potencial de contribuir na tolerância a estresses em plantas, esta estratégia é pouco compreendida em gramíneas, entre elas a cana-de-açúcar. Neste sentido, o presente trabalho pretende compreender aspectos moleculares relativos à produção de RFOs em cana-de-açúcar e sua relação com estresses abióticos e desenvolvimento. Para tanto, foram avaliados transcricionalmente genes relacionados a síntese de RFOs em cana sob estresse hídrico, bem como obteve-se plantas transgênicas com expressão constitutiva do gene CaGolS2, uma galactinol sintase de cafeeiro. Sob estresse hídrico, gene ScGolS1 teve seu nível transcricional reduzido em folhas e induzido em colmo. ScRFS1 nos dois tecidos tem o padrão transcricional diretamente relacionado ao aumento da severidade do estresse, e o mesmo é observado em ScSTS1. Foram também obtidos 10 eventos transgênicos de cana-de-açúcar com a região codificante do gene CaGolS2 de Coffea arabica, dos quais... / Abstract: Bioenergy application of sugarcane byproducts are making this crop one of the most important in the international agribusiness investments. To meet global demand and expand the sugarcane sector, genetic engineering strategies generating transgenic plants more tolerance to biotic and abiotic stresses is a promising to improve productivity. One of the most relevant mechanism related to stress tolerance in plants involves the accumulation of distinct solutes. The Raffinose Oligosaccharids Family synthesis starts from the successive addition of galactosyl radicals to a sucrose molecule, in a reaction catalyzed by galactinol synthase (GolS), raffinose synthase and stachyose synthase. GolS plays a key role in RFOs production in model plants. Although the stress-responsive action of RFOs may improve abiotic stress tolerance in plants, these mechanisms are almost completely unknown in grasses, like sugarcane. In this context, this study aims to understand molecular aspects of RFOs synthesis and its relation with abiotic stresses. We have evaluated the transcriptional level of genes related RFOs synthesis under water stress and we produced transgenic plants constitutively expressing a coffee galactinol synthase (CaGolS2). Under water stress, ScGolS1 was downregulated in leaves, but upregulated in stems. ScRFS1 and ScSTS1 were upregulated in both tissues, in a direct correlation between transcription level and stress. We produced 10 transgenic events containing the coding region of CaGolS2; in six events, the transgene were transcriptionally active. Transgenic plants presented differences in morphology and carbon assimilation when compared to non-transgenic controls. Overall, we inferred that the stress-responsive pattern of RFO synthesis genes might help carbon relocation during water stress. Raffinose and stachyose seems to have greater impact than galactinol in this process. Furthermore, CaGolS2 transgenic plants have promising traits for... / Mestre

Dry bean breeding programs have made significant advances in combating both abiotic and biotic stresses as well as improving plant architectural traits via selective breeding. Flooding can cause complete crop loss in dry bean. On the other hand, breeding for an upright architecture in dry bean has been a breeding target in several programs. However, the stem cell wall components underlying this change have yet to be studied. This research focused on analyzing the cell wall components that might be involved in dry bean architecture as well as pre-germination flooding tolerance in dry bean. For the plant architecture study, two significant genomic regions were identified on Pv07 and Pv08 associated with lignin accumulation in dry bean. For the pre-germination flooding study, one unpigmented seed coat genotype (Verano) and three pigmented seed coat genotypes (Indeterminate Jamaica Red, Durango, and Midnight) had germination rates similar to that of the tolerant check.

Orientador: Carmen Regina Marcati / Coorientador: Magali Ribeiro da Silva / Resumo: Em ambientes tropicais, a disponibilidade hídrica é um dos principais fatores que interferem na atividade cambial das espécies vegetais. Estudos recentes, em campo, indicam também o comprimento do dia e a temperatura como sinalizadores importantes da atividade cambial nestas espécies. Este estudo experimental visa contribuir para o entendimento da influência dos fatores abióticos, água, comprimento do dia e temperatura, na atividade cambial em plantas com um ano de idade de Cordiera concolor (Cham.) Kuntze (Rubiaceae). A espécie, sempre-verde e arbustiva, é nativa, comum no cerrado paulista, e possui camadas de crescimento demarcadas por faixas marginais de parênquima axial. Realizamos dois experimentos (n=45 plantas cada um), sob regime hídrico controlado e sob comprimento do dia e temperatura naturais, um no início da primavera, quando o fotoperíodo aumenta de 11 para 12 horas e a temperatura média é de 19,9ºC e outro no final do verão, quando o fotoperíodo diminui de 12 horas para 11 horas e a temperatura média é de 23,9ºC, ambos durante cinco semanas. Cada experimento continha os mesmos três tratamentos hídricos, com 15 plantas cada, obtidos a partir de uma curva de retenção hídrica de solo de cerrado sensu stricto: saturação hídrica (21% de umidade), capacidade de campo (8% de umidade) e deficiência hídrica (3% de umidade). Ao final de cada semana, sorteamos três plantas de cada tratamento e coletamos a região mais desenvolvida do eixo caulinar. Obtivemos secções transve... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In tropics, the water availability is one of the main factors interfering in the cambial activity of plants. Recent studies, in the field, also indicate that day length and temperature are important signals of the cambial activity in tropical plants. This experimental study aims to contribute for understanding the role of these abiotic factors (water, day length and temperature) on cambial activity in 1-year-old plants of Cordiera concolor (Cham.) Kuntze (Rubiaceae). This species, evergreen and shrubby, is native and common in Cerrado of São Paulo, and have growth layers demarcated by axial parenchyma marginal bands. We conducted two experiments (n = 45 plants, each), under controlled water regimes and under natural day length and temperature, one in early spring, when the day length increases from 11 hours to 12 hours and mean temperature is 19,9ºC and another in late summer, when day length decreases from 12 hours to 11 hours and mean temperature is 23,9ºC, both for five weeks. Each experiment contained the same three water treatments, obtained from a water retention curve of cerrado soil, with 15 plants each: waterlogging (21% moisture), field capacity (8% moisture) and water deficit (3% moisture). At the end of each week, we randomly selected three plants of each treatment and collected the most developed region of the main stem. We obtained transverse and tangential and radial sections for cambial activity analyses. We identified cambial activity by mitotic figures and the presence of recently formed periclinal cell walls. We used fifteen sequential radial rows in the cambial zone to count the newly formed periclinal cell walls. We analyzed the data using generalized linear models (GLM) which allowed us to observe that in early spring, regardless of the amount of water, the cambial activity is increased by day length. In late summer, the amount... (Complete abstract click electronic access below) / Doutor

A dissertation submitted to the Faculty of Education in fulfillment of the requirements of the Degree of Doctor Of Education in the Department of Educational Psychology at the University of Zululand, 2018 / Teaching is regarded by many as one of the most stressful occupations, as evidenced by reports of academic results consistently poor in rural schools and teachers leaving the profession each day. Stress in general has always been a concern in many schools. The aim of this study was to investigate the effect of teacher stress on learner academic performance in rural secondary schools. This study used both quantitative and qualitative research approaches in which questionnaires and interviews were used for data collection processes. Simple random sampling and purposive sampling procedures were used to select participants from rural secondary schools in Vhembe District with a matric pass rate of less than sixty percent over a period of five years. Quantitative data was analyzed using IBM Statistical package for Social Sciences (SPSS) Version 24 (IBM SPSS statistics), and Atlas.ti Version 6 programme for qualitative data. Results showed that teachers in secondary schools in the rural areas experience high levels of stress which has adverse effects on learner academic performance. These results guided me in developing the Three Pillars Teacher Stress Coping Model to assist teachers in rural areas to alleviate the stress they experience as they promote teaching and learning. The study contributed to the literature on the effect of the experience of stress by teachers on learner academic performance in rural secondary schools. / National Research Foundation Of South Africa (Grant Number CPT160513164973 and 105246

An increased understanding of species-specific behavioral needs has lead zoos to focus on providing more naturalistic and stimulating environments. Scientific assessments of how changes in habitat affect animal behavior are necessary in improving overall animal welfare. This study examined the move of three orangutans housed at the Oregon Zoo into a new and innovative exhibit. Post-occupancy evaluation (POE), which offers systematic information regarding the success or failure of the built environment (Maple & Finlay, 1987), was utilized to effectively evaluate the results of the move. The collection of behavioral data and adrenal activity monitoring through collection of non-invasive saliva, urine and hair provided a comprehensive methodology for comparing changes in behavior and physiological functioning. Behavioral results showed that following the move to the new enclosure animals spent less time inactive, more time at higher elevations and utilized exhibit structures at a greater frequency. Hormonal results suggest that detection of cortisol in orangutan hair could be a useful tool for monitoring chronic stress.

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Environmental stress conditions can drastically affect plant growth and productivity. In contrast to soil moisture or salinity that can gradually change over a period of days or weeks, changes in light intensity or temperature can occur very rapidly, sometimes over the course of minutes or seconds. So, in our study we have taken an metabolomics approach to identify the rapid response of plants to light stress. In the first part we have focused on the ultrafast (0-90 sec) metabolic response of local tissues to light stress and in the second part we analyzed the metabolic response associated with rapid systemic signaling (0-12 min). Analysis of the rapid response of Arabidopsis to light stress has revealed 111 metabolites that significantly alter in their level during the first 90 sec of light stress exposure. We further show that the levels of free and total glutathione accumulate rapidly during light stress in Arabidopsis and that the accumulation of total glutathione during light stress is dependent on an increase in nitric oxide (NO) levels. We further suggest that the increase in precursors for glutathione biosynthesis could be linked to alterations in photorespiration, and that phosphoenolpyruvate could represent a major energy and carbon source for rapid metabolic responses. Taken together, our analysis could be used as an initial road map for the identification of different pathways that could be used to augment the rapid response of plants to abiotic stress. In addition, it highlights the important role of glutathione in initial stage of light stress response. Light-induced rapid systemic signaling and systemic acquired acclimation (SAA) are thought to play an important role in the response of plants to different abiotic stresses. Although molecular and metabolic responses to light stress have been extensively studied in local leaves, and to a lesser degree in systemic leaves, very little is known about the metabolic responses that occur in the different tissues that connect the local to the systemic leaves. These could be important in defining the specificity of the systemic response as well as in supporting the propagation of different systemic signals, such as the reactive oxygen species (ROS) wave. Here we report that local application of light stress to one rosette leaf resulted in a metabolic response that encompassed local, systemic and transport tissues (tissues that connect the local and systemic tissues), demonstrating a high degree of physical and metabolic continuity between different tissues throughout the plant. We further show that the response of many of the systemically altered metabolites could be associated with the function of the ROS wave, and that the level of eight different metabolites is altered in a similar way in all tissues tested (local, systemic, and transport tissues). These compounds could define a core metabolic signature for light stress that propagates from the local to the systemic leaves. Taken together, our findings suggest that metabolic changes occurring in cells that connect the local and systemic tissues could play an important role in mediating rapid systemic signaling and systemic acquired acclimation to light stress.