ITQB: PCB - PhD Theses
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- Sustainable production of high-value molecules using engineered plant cultured cellsPublication . Rebelo, Bárbara Almeida; Abranches, Rita; Ventura, Rita"Plant cell suspension cultures offer a promising and sustainable platform for the production of high-value compounds. In this thesis, the main objective was to explore their versatility beyond recombinant protein production, focusing on the biosynthesis of secondary metabolites, particularly the commercially valuable carotenoids. Among them, ketocarotenoids such as canthaxanthin and astaxanthin are especially valued for their antioxidant properties and strong pigmentation. However, their production remains costly due to limited natural sources and complex chemical synthesis. To address this challenge, Nicotiana tabacum BY-2 cells were used as a model system to establish the workflow for both metabolic engineering and transcriptomic and phenotypic characterization.(...)"
- Dissecting grapevine graft incompatibility with particular reference to its early detection and underlying causesPublication . Tedesco, Sara; Fevereiro, Pedro; Kragler, Friedrich"Grafting is an ancient agricultural method widely practice already in Greek and Roman times and consists in the joining of two different plant parts, the scion (shoot) and the rootstock (roots), in a way in which they will develop and functioning as a single plant. Over time, grafting evolved from a way of propagating plants to using them to improve their characteristics. For instance, Vitis vinifera are grafted since the middle of the 19th century onto American grapevine rootstocks to exploit their resistance to the Phylloxera, which would otherwise be lethal for European vines. One important aspect of grafting is graft incompatibility which refers to the early or later failure of the graft union which delays rootstock breeding selection and causes losses to farmers and nurseries.(...)"
- High-value molecules from Cynara cardunculus L.Publication . Folgado, André; Abranches, Rita"Cynara cardunculus L. also known as cardoon or thistle flower is a plant endemic to the Mediterranean basin region. In some countries, the flower of cardoon is harvested and used as milk clotting agent in traditional cheese manufacturing. This process occurs due to the activity of aspartic proteases (APs) present in the flower, known as cardosins and cyprosins. Despite this economic importance, the use of cardoon for industrial cheese manufacturing is still hampered by variability in cardoon populations which leads to unpredictability in the milk clotting process thus affecting control over the final product. "
- Chromatin dynamics in Arbidopsis development: a live cell imaging approachPublication . Rosa, Stefanie; Abranches, RitaThe proper development of multicellular organisms demands the distinct specification of a variety of specialized cell types. While this is one of the oldest statements of developmental genetics, how different patterns of gene expression are established in genetically identical cells and maintained during somatic cell divisions is still an active topic of research. Chromatin structure is now recognized to regulate gene activity playing a crucial role in cell differentiation and development. Chromatin is not simply a packaging tool but a dynamic entity that reflects the regulatory cues necessary to program appropriate cellular pathways. There are several ways by which chromatin structure can be remodelled. These mechanisms include DNA-methylation, post-translational modifications of histone proteins, histone variants and, nuclear localization. While the dynamic nature of chromatin structure has been previously described its biological function and repercussions on development are only now beginning to be revealed. In this work we used in vivo microscopy techniques to assess how different aspects of chromatin organization play a role on various aspects of development.(...)
- Genetics of berry colour and anthocyanin content variation in grapevine (Vitis vinifera L.subsp. vinifera)Publication . Cardoso, Silvana Coelho; Fevereiro, Pedro; Dias, José Eduardo EirasAnthocyanin content of grape berry skin determines the colour of grapes and wine. This trait has been widely studied due to its importance for grape and wine marketing and also due to the antioxidant properties of anthocyanins. In this thesis the variation of this trait was investigated within and between cultivars. DNA sequence variation and differential gene expression were studied among clones of the cultivars Aragonez and Negra Mole. Grape colour phenotyping was explored using different phenotyping approaches. Association mapping was performed for a sample of 149 cultivars and association mapping methodologies considering structure and relatedness in the sample were discussed. It was observed that no DNA sequence variation was present in the studied genomic regions between different clones of the same cultivar. Differential expression between Aragonez clones with contrasting values of skin total anthocyanin concentration was found to be very subtle not showing any significant results after correction for multiple testing and with two fold-change. However, relaxing statistical stringency and focusing on functional groups of interest (flavonoid metabolism and transcription factors) a list of 24 genes of interest was identified. This included two genes involved in the flavonoid metabolism, coding enzymes related with the glucosylation of flavonoids and transcription factors of the following families: Myb, Myc, zinc fingers, WRKY, DOF, GRAS, homeobox domain, YABBY, basic-leucine zipper, pathogenesisrelated and plant homeodomain finger.(...)