Percorrer por autor "Fernandes, Gisela Mariana"
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- Caracterização morfológica e genética de cultivares de oliveiras centenárias e tradicionais para a obtenção de produtos diferenciadosPublication . Fernandes, Gisela Mariana; Baptista, Paula; Pereira, J.A.As oliveiras centenárias são uma marca da paisagem Transmontana e a obtenção de azeites diferenciados destas árvores poderá ser um nicho a explorar, com vantagens económicas, sociais e ambientais. Esta estratégia só será viável após a caracterização genética das cultivares de oliveiras centenárias existentes na região. O presente trabalho teve como objetivo caracterizar morfologicamente e geneticamente, através da análise por microssatélites, cultivares de oliveiras centenárias existentes na região Transmontana. Neste estudo foram ainda incluídas cultivares tradicionais frequentemente plantadas na região de forma a elucidar possíveis relações de filogenia entre estas e as centenárias. Os resultados da análise morfológica do fruto, endocarpo e folha das oliveiras amostradas (15 tradicionais e 17 centenárias) não permitiram uma diferenciação completa das duas populações. Os caracteres mais diferenciadores nas oliveiras tradicionais estavam relacionadas com a folha e a forma do fruto, enquanto que nas centenárias estavam relacionadas com o peso e diâmetro do fruto e endocarpo. As características do endocarpo foram as que permitiram uma maior diferenciação das duas populações. Os 12 loci utilizados na análise genética permitiram detetar 74 alelos nas 32 oliveiras e evidenciaram a existência de uma grande diversidade. A população de oliveiras centenárias apresentou uma maior diversidade genética e número de alelos privados, comparativamente com a população de oliveiras novas. Em ambas as populações foi registado um excesso de heterozigóticos. Apesar do baixo valor de FST observado (0,030), a análise do structure permitiu a diferenciação das duas populações de oliveiras e sugeriu a possibilidade de algumas das oliveiras novas terem origem das centenárias. Dos loci estudados, UDO-011 e DCA18 foram os que permitiram uma maior diferenciação das duas populações podendo ser bastante úteis na certificação de oliveiras centenárias. O teste de Mantel evidenciou uma correlação positiva e altamente significativa entre os caracteres morfológicos, em especial os relacionados com o fruto, e a análise molecular. Com base nos resultados obtidos é recomendável a conservação da população de oliveiras centenárias por apresentar uma grande diversidade genética.
- Characterization of the endophytic fungal communities associated to Coleostephus myconis: looking for potential repellent/attractant compounds towards Philaenus spumariusPublication . Cameirão, Cristina; Fernandes, Gisela Mariana; Martins, Fátima; Pereira, J.A.; Baptista, PaulaPhilaenus spumarius is a xylem feeding insect identified so far as the only vector involved in the first European outbreak of the phytobacterium Xylella fastidiosa, affecting and devastating olive groves in Italy. One approach to reduce X. fastidiosa transmission could rely in the vector control through the use of baits to attract and/or repel de insect. Fungal endophytes inhabiting plants provide a source of candidate repellent/attractant compounds. In this work, the endophytic fungi community associated to the weed Coleostephus myconis, was studied in order to identified potential fungi that can be used as attractants or repellents of P. spumarius. Coleostephus myconis is common in olive groves and preferentially used by P. spumarius for the nymph development. Fungi were isolated from the stems, leaves and inflorescences from plants with three levels of P. spumarius infestation (i.e. no infestation, moderate and high infestation). The fungal isolates obtained were identified by sequencing the ITS region of rDNA and the partial tef1. Overall, was obtained 138 taxa belonging to 37 different genera. The endophytic community composition differs between infested and non-infested plants, solely at stems level, where the P. spumarius foam nests are present. The fungal genera, Cytospora, Diaporthe and Penicillium, which are well-known with producers of volatiles compounds repellent activity against insect, were found only on non-infested plants. Botrytis was restricted to infested plants. The behavioral responses and preferences of P. spumarius for C. myconis plants colonized by these endophytes should be investigated in the future.
- Estrutura e diversidade genética de oliveiras centenárias da região TransmontanaPublication . Fernandes, Gisela Mariana; Pereira, J.A.; Henriques, Dora; Pinto, M. Alice; Baptista, PaulaAs oliveiras são componentes importantes da paisagem Transmontana, região onde ainda é possível encontrar árvores centenárias. Estas, podem ser uma fonte de produtos diferenciados azeitonas de mesa e azeites estratégia que interessa valorizar. Contudo, o desconhecimento sobre a sua diversidade e estrutura populacional na região poderá inviabilizar esta estratégia, por não ser possível definir medidas de gestão e conservação adequadas para a sua proteção. Neste sentido, no presente trabalho pretendeu-se caracterizar geneticamente, através da análise por microssatélites, 17 exemplares de oliveiras centenárias da região de Trás-os-Montes e elucidar possíveis relações de filogenia com 15 exemplares de cultivares conhecidas na região.
- Exploitation of Coleostephus myconis-associated endophytic fungi repel or attract Xylella fastidiosa vectorPublication . Cameirão, Cristina; Fernandes, Gisela Mariana; Martins, Fátima; Pinto, Maria Beatriz; Pereira, J.A.; Baptista, PaulaXylella fastIdiosa is a bacterium transmitted by insectvectors that cause high losses in a variety ofagriculturally important crops. In Europe, an outbreak ofthe disease was recently detected in olive trees, being Philaenus spumarius só far identífied as the only vector involved in this outbreak. Thus, vector contrai by using bait plants and/or insect repellents that emit volatile compounds produced by microorganisms that colonize host plants [endophyte] may help to reduce the dissemination ofthe disease. In this work the endophytic fungal community of Coleostephus myconis, a ground cover plant present in the olive graves and commonly infested by P. spumarius, was studied. Fungi were isolated from stems, leaves and inflorescences ofplants with three leveis of P. spumarius infestation, collected in an olive grove located in Mirandela. The fungal isolates obtained were identified by sequencing the ITS region of rDNA the partial tefl. A total of 121 species/genera were identified, bemg Alternaria, Chalastospora and Valsa the most abundant genera. The diversity and abundance of endophytic fungi was higher in the leaf and inflorescences than in the stem. The composition and diversity of endophytic fungal community was different between infested and non-infested plants, especially at the levei of their leaves. Endophyte community similarity between the different plant organs was low, especially between stem and inflorescences. Altogether, the results show that P. spumaríus affects the composition and structure ofendophytic fungal community associated to C. myconis, especially in their leaves. The effect of this change in the fungal community in attractiveness/ repulsion of P. spumarius should be studied in the future.
- The effect of Philaenus spumarius feeding on the endophytic fungi community of Coleostephus myconis and its possible applicability in the insect biocontrolPublication . Cameirão, Cristina; Fernandes, Gisela Mariana; Martins, Fátima; Pereira, J.A.; Baptista, PaulaPhilaenus spumarius was recently confirmed as the European vector for the ongoing Xylella fastidiosa outbreak in the olive orchards of Southern Italy. In the northeast region of Portugal, P. spumarius is widespread and common in olive groves. In these groves was observed that their nymphs feed preferentially on the weed Coleostephus myconis, displaying in the same time period and area different levels of infestation. This work aims to assess the correlation between the fungal endophytic communities inhabiting C. myconis with the feeding preference of P. spumarius. Fungi were isolated from stems, leaves and inflorescences of plants with three levels of P. spumarius infestation (no infestation, moderate and high infestation), collected in an olive grove located in Mirandela. The fungal isolates were further identified by sequencing the ITS region of rDNA and the partial tef1. A total of 138 OTUs belonging to 37 genera were isolated, being Alternaria, Valsa, Cladosporium and Chalastospora the most abundant genera. An increase in overall endophytic fungal abundance and richness was observed across infestation levels, in particular of isolates belonging to Chalastospora and Cladosporium. In contrast, Biscogniauxia, Chaetomium and Stemphylium, decreased across the levels of infestation. Differences in fungal composition between non-infested and infested plants were particularly observed in stems, where the P. spumarius foam nests are present. Some genera were exclusively found either in non-infested or in infested plants. Our survey provides fungal candidates to further evaluate their role in the repellency/attraction of P. spumarius in order to develop new management tools against this insect.