ITQB: GPS - PhD Theses
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- Towards rice multibiofortificationPublication . Faustino, Maria Vicente; Oliveira, Margarida; van der Straeten, Dominique"Ensuring a sufficient, nutri ous and accessible food supply remains a significant challenge, in par cular in low and middle income countries. Although widely cul vated crops, such as rice, provide enough calories, they lack sufficient levels of essen al micronutrients, nega vely impac ng health, compromising social and economic progress. Biofor fica on through metabolic engineering of staple crops offers a cost-effec ve solu on to deliver essen al minerals and vitamins to popula ons with limited access to diverse diets.(...)"
- The role of soil microbiota and environmental cues on the regulation of maize developmentPublication . Custódio, Valéria Santos; Oliveira, Margarida; Broadley, Martin; Castrillo, Gabriel"As a result of climate change, the amount of greenhouse gases in the atmosphere is changing, temperatures are rising, precipitation patterns are changing, and extreme weather events are occurring more frequently. These changes accounted for 25% of average yield losses for low-latitude maize. Several strategies have been developed to tackle the reduction of productivity, such as altering planting and harvesting time, sowing crops with a short life cycle, applying crop rotation and irrigation techniques, and introducing variation in cropping systems. Besides these strategies, a knowledge-driven approach to manage the soil microbiota rather than merely applying microorganisms has been described as promising to sustainably increase crop yield. Taking this into consideration, we have designed a holistic approach that combines the characterization of a collection of agricultural soils, soil bacterial composition, plant microbiota, and nutrition availability to understand how plant mechanisms and microbiota coordinate to ensure the adaptative growth of leaves in the model plant Zea mays (maize).(...)"
- Histologic and molecular characterization of root phellem development and suberization from Arabidopsis thaliana to Quercus suberPublication . Leal, Ana Rita Mendes; Oliveira, Maria Margarida; Beeckman, Tom"Adaptation of land plants to the terrestrial environment required the development of several specialized structures and chemicals, namely organs for anchorage and absorption of water and mineral (roots), efficient conducting systems (xylem and phloem), as well as effective support tissues (parenchyma and collenchyma). Moreover, transition from aquatic to terrestrial environment led to an increased water potential between plant body and the environment, driving the development of protective and specialized diffusion barriers that could mitigate uncontrolled water movements and water loss.(...)"
- Jatropha curcas drought response -Publication . Sapeta, H.; Oliveira, Margarida"Humans depend on plants for food, health and ultimately for their survival. However, the increasing human population has been gradually reducing the land available for agriculture and further competing for resources such as water. Furthermore, drought is a major environmental factor threatening food security. Indeed, drought is predicted to increase in the near future due to three major trends: (1) global climate change – with higher temperatures and increased frequency and severity of drought episodes; (2) increasing competition for limited water supplies; and, (3) plant inability to cope with fast environmental changes. To address the drought problem at crop level, several aspects must be improved at the level of agronomy (e.g. tillage and irrigation practices) and plant biology (e.g. varieties improved through modern breeding technologies). In this context, a better understanding of the drought response of tolerant plants can help planning improved and more targeted breeding strategies."
- Os CPK17Publication . Pina, Maria Cecília Marques dos Santos Mousinho Almadanim da Câmara; Oliveira, Maria Margarida; Negrão, Sónia; Abreu, Isabel"Rice is essential to feed the human population and is a key component in many food security programs. To meet the increasing food demand without further sacrificing natural areas, crop yields must be increased, which can be achieved by reducing losses due to biotic and abiotic stress conditions that compromise the production potential. Throughout evolution, plants have adapted to a diversity of new habitats, developing fascinating complex mechanisms to overcome adverse environmental conditions. The goal of this thesis was to explore rice natural genetic diversity potentially useful to integrate into breeding programs, and to identify and further characterize a selected candidate gene with impact on abiotic stress tolerance.(...)"
- Insights into the epigenetic regulation of the rice genome: the role of DNA methylation and histone modifications in salt stress responsesPublication . Ferreira, Liliana de Jesus Duarte; Santos, Ana Paula; Oliveira, MargaridaPlants exhibit complex and integrated strategies to respond to stressful events involving particular signalling pathways, transcription factors and a number of specific stress-responsive genes. In addition, the regulation of genome accessibility is ensured by an efficient network of chromatin organization and epigenetic mechanisms which imply a heritable influence on gene activity that is not associated with changes in the DNA sequence. However, the functional role of these factors in plant response to stressful conditions is still largely unknown and so far direct connections between epigenome regulation and phenotypic plasticity are still poorly explained.(...)
- Regulation of the rice gene OsRMC under salt stress: identification and functional characterization of novel transcription factorsPublication . Serra, Tânia Sofia Lobato Paulo; Saibo, Nelson; Oliveira, MargaridaRice (Oryza sativa L.) is cultivated worldwide and is the staple food for more than one-half of the world population. Abiotic stress conditions, such as high salinity, drought and low temperature have a strong negative effect on rice production. High salinity severely affects rice growth and reduces grain yield, as it induces late flowering and lowers pollen viability. To cope with saline environments, plants rely on the perception and transduction of stress signals through specific response pathways, which activate several adaptation mechanisms.(...)
- Proteomic and Transcriptomic Approaches to Abiotic Stress Tolerance in Rice (Oryza sativaL.)Publication . Resende, Ana Paula Martins Farinha; Oliveira, M. Margarida; Pagés, MontserratCereals are the most important food source, and rice (Oryza sativa L.) alois the staple crop for more than half of the world’s population. Environmenstresses limit plant growth and productivity, and in the case of rice, drouhas become the most serious constraint to yield potential in all agro-climazones. The challenge for the next generations is thus to achievesustainable rice production with less arable land, reduced inputs agrochemicals (fertilizers and pesticides) and above all, with limited wasupply, given the increasing scarcity of water resources at global level(...)
- Insights into the role of almond CBF transcription factors in the environmental control of cold acclimation and dormancy breakPublication . Barros, Pedro Miguel; Oliveira, M. Margarida; Saibo, Nelson J.Cold is an important environmental factor that may influence plant survival and productivity. It also plays a crucial role in the seasonal development of perennial plants by regulating the extent of (winter) dormancy and that of vegetative and reproductive growth periods. This aspect is particularly relevant in fruit trees, since it may directly impact fruit production. The Prunus genus includes economically relevant species, and the almond (Prunus dulcis Mill.) stands out for its high range of genetic variability, thus being an interesting model to study specific traits of agricultural interest. Considering that low temperature signalling pathways are still poorly understood in Prunus spp., this study aimed to identify and elucidate, in almonds, the function of members of the C-repeat Binding Factor (CBF) family of transcription factors (TFs) which are known to be relevant in the response to cold. Therefore, two CBF genes (PrdCBF1 and - 2) and their corresponding regulatory regions were cloned and sequenced in this species. Southern-blot analysis and further comparisons to the recently available peach genome revealed that the almond CBF family is composed of at least five members, located in close proximity in chromosome 5. In addition, a mapping analysis suggested an association between PrdCBFs and PrdDehydrin1 (PrdDHN1, a putative CBF target gene, involved in cold acclimation) to recently reported QTLs controlling chilling requirements and blooming time. However, further analyses are necessary to confirm this association.(...)
- Novel transcription factors regulating the expression of the rice gene OsDREB1BPublication . Figueiredo, Duarte Dionísio; Oliveira, M. Margarida; Saibo, Nelson J.Environmental stresses are responsible for major losses in crop production worldwide. Due to an increasing world population, there is a higher demand for food, feed and fuel, which requires the development of new plant varieties with an increased yield, particularly under adverse environmental conditions. Transcription Factors (TFs) are promising candidates for plant improvement, since a single TF can modulate the expression of several genes. The AP2/ERF family of transcriptional regulators and, namely, the TFs belonging to the DREB1/CBF sub-family were described as major regulators of plant responses to abiotic stresses. Nevertheless, the transcriptional regulation of the genes coding for these TFs is still poorly understood. We focused our research on the rice gene OsDREB1B, whose gene expression had been previously described as responsive to abiotic stress, namely cold. Using semi-quantitative RT-PCR, we confirmed the cold-induction of this gene, but also observed that its response is different depending on the severity of the stress. Moreover, we observed that this gene is highly induced in response to drought stress in roots, and also in response to mechanical stress. Using the Yeast One-Hybrid system and the promoter of OsDREB1B as bait, we have screened a rice cold-induced cDNA expression library. Thereby we identified eight TFs as binding to OsDREB1B promoter: seven Zinc Finger TFs, of which three C2H2-type and four Zn Finger-Homeodomain (ZF-HD) TFs, as well as one bHLH TF, predicted as a putative Phytochrome Interacting Factor (PIF).(...)