Abordagens moleculares no estudo da diversidade microbiana

A importância dos microrganismos na manutenção da vida na Terra é reconhecida por todos. Estes organismos microscópicos são relevantes em áreas tão diversas como a Saúde, Agricultura, Indústria ou Ambiente. O número estimado de todas as espécies é de 100 milhões, das quais 2 milhões foram formalmente descritas. Das cerca de 1,5 a 3,5 milhões de espécies fúngicas que se estimam existir, apenas 5% se encontram descritas. Tradicionalmente, a identificação de espécies de fungos baseia-se no seu isolamento e análise da morfologia das suas estruturas reprodutoras. Embora de grande utilidade, a caracterização morfológica é limitada devido ao reduzido número de caracteres que podem ser analisados, da dependência das condições de cultura e das variações intrínsecas do microrganismo. Actualmente, métodos moleculares baseados na sequenciação do espaçador interno do transcrito de rDNA (ITS) têm vindo a ser utilizados na identificação eficaz de espécies fúngicas. Estudos populacionais têm recorrido à amplificação da região ITS e comparação dos perfis electroforéticos em gradientes desnaturantes (DGGE ou TGGE) de diferentes amostras. Recentemente, o desenvolvimento de técnicas de sequenciação massiva permitiram a emergência de uma nova área- a metagenómica - que pode ser aplicada a comunidades de microrganismos sem a necessidade de os isolar ou cultivar. Este facto adquire especial relevância por se estimar que apenas 17% dos fungos serão capazes de ser cultivados in vitro. Nesta apresentação serão abordados as estratégias que permitiram a evolução da metagenómica. Os desafios da identificação de microrganismos em comunidades serão discutidos, focando o caso particular da diversidade fúngica em amostras de solos.Financiado pela FCT, projecto PTDC/AGR-AAM/099556/200

Vantagens e desvantagens da relação entre plantas e fungos

Apresentação efetuada nas III Jornadas Micológicas, Braga, 2011Os fungos são capazes de estabelecer múltiplas associações/relações com as plantas. Apesar de muitas dessas relações se revelarem prejudiciais, outras apresentam vantagens significativas ao nível do desenvolvimento, nutrição e sanidade das plantas. Nesta comunicação será particularmente abordada a associação sirnbiótica que ocorre entre raízes e fungos do solo - micorrização - referindo-se as vantagens que daí advêm para plantas, fungos e inclusivamente para o Homem

Distinguishing allies from enemies-a way for a new green revolution

Plants are continually interacting in different ways and levels with microbes, resulting in direct or indirect effects on plant development and fitness. Many plant-microbe interactions are beneficial and promote plant growth and development, while others have harmful effects and cause plant diseases. Given the permanent and simultaneous contact with beneficial and harmful microbes, plants should avoid being infected by pathogens while promoting mutualistic relationships. The way plants perceive multiple microbes and trigger plant responses suggests a common origin of both types of interaction. Despite the recent advances in this topic, the exploitation of mutualistic relations has still not been fully achieved. The holistic view of different agroecosystem factors, including biotic and abiotic aspects, as well as agricultural practices, must also be considered. This approach could pave the way for a new green revolution that will allow providing food to a growing human population in the context of threat such as that resulting from climate change.This work was supported by FCT (Fundacao para a Ciencia e a Tecnologia) within the framework of CBMA (UIDB/04050/2020) and CIMO (UID/AGR/00690/2020) I&D centers

As ferramentas de avaliação na Blackboard: um testemunho

Apresentação efectuada no "Seminário de Ensino colaborativo e de e-learning”, em Braga, 2011Partilha da experiência pessoal de avaliação com os recursos disponíveis na plataforma Blackboard. Criação de bancos de questões e os testes. Utilização dos recursos disponíveis no GAE

An improved method for high-quality RNA isolation from needles of adult maritime pine trees

Conventional RNA isolation methods optimised for pine seedlings have been shown to produce poor quality RNA when applied to needles of adult pine trees. We describe here a modified procedure to isolate high pure RNA from needles of thirty-year-old maritime pines, exhibiting high levels of phenolics, polysaccharides and RNases. Major changes were the inclusion of proteinase K in the extraction medium followed by incubation at 42°C. Integrity and purity were evaluated by denaturing gel electrophoresis and by spectrophotometry (A260/A230 and A260/A280). Total RNA could be successfully used for poly(A)+-RNA isolation and cDNA library construction.Fundação para a Ciência e a Tecnologia (FCT) - grant ref. SFRH/BD/3194/2000

Molecular aproach on the study of infection of Pinus pinaster Ait. by the fungus Lophodermium seditiosum

Poster apresentado no 10th International Congress on Molecular Plant-Microbe Interactions, Madison, Wisconsin, Estados Unidos da América.The fungi genus Lophodermium comprises several species known to intervene in the degradation process of pine needles. Amongst these species, only L. seditiosum is known to be pathogenic, as it is able to infect healthy needles in young pine populations, spreading from stomata and leading to the death of the needle (needle cast disease). Maritime pine (Pinus pinaster, Ait) is one of the most relevant forest species in SW Europe. Needle cast disease, by attacking young plants, leads to two main events: the lack of self regeneration in natural populations, and complete destruction of pine nurseries. The purpose of our study is to understand the nature of the infection of Pinus pinaster Ait. by L. seditiosum and ultimately gain some knowledge on the overall response of Conipherophyta to infection. As a first step towards this goal, a cDNA library of Pinus pinaster was constructed. Subsequent effort has been directed towards the screening of genes encoding PR proteins involved in host-pathogen interaction, as well as oxidative stress enzymes. In addition, PCR amplification using degenerate primers is in progress in order to allow the identification of putative Resistance genes.Fundação para a Ciência e a Tecnologia (FCT) - grant ref. SFRH/BD/3194/200

Phytochemicals properties and antioxidant activities of some accessions of Phaseolus vulgaris L

Common bean is a legume important in Mediterranean diet with interesting nutritional food characteristics due to its proteins, fibers and antioxidant activity. There is an increased interest among consumers in foods rich in natural antioxidants for maintaining and improving health. Beyond this, beans are a low-price food and an excellent complement for the population with low income. There are some differences in the phenolic and flavonoid compounds content and antioxidant capacity between accessions of common bean. In this study, 15 traditional Portuguese and 1 Greek accessions of Phaseolus vulgaris L. were analyzed. Total phenols, ortho-diphenols and flavonoid contents were investigated and antioxidant activity were measured by different assays (DPPH, ABTS) which may give a better characterization of this activity

Transcriptome of Quercus suber challenged by drought, salinity, and oxidative stresses

Comunicação em painelThe cork oak (Quercus suber) forest (the “montado”) is a unique and emblematic resource for Portugal, due to its ecological, socio-economic significance, and the commercial value of cork. Plant abiotic stresses, particularly reduced water availability and extreme temperatures, are substantial constraints to agricultural and agro-forestry production. In the particular case of cork oak, the damaging land-use policies, the climate change, and imposition of abiotic stresses related with high light intensities have been threatening the cork oak forests. The adaptation to abiotic stresses comprises a series of morphological, physiological, biochemical and molecular changes controlled by complex molecular networks. Recent advances in increasing plant tolerance were achieved after the identification of specific genes suited for plant genetic engineering. However, as abiotic stress is commonly present in the field as a combination of different stresses, the complex plant response mechanisms are far from being elucidated. This work is part of a coordinated effort to uncover the transcriptome of Q. suber and attention was paid to the identification of expressed sequence tags (ESTs) involved in responses to distinct abiotic stress challenges, namely drought, salt and oxidative stresses.This work was supported by the FCT project SOBREIRO/0033/200

Efeito de extractos de raízes eliciadas de Castanea sativa no crescimento do fungo ectomicorrízico Pisolithus tinctorius

O castanheiro (Castanea sativa Mill.) estabelece associação com numerosas espécies de fungos ectomicorrízicos, estando descritos os efeitos benéficos para a planta após micorrização com Pisolithus tinctorius. Neste processo é essencial que ocorra a troca de sinais entre os simbiontes, para que seja reconhecida a sua compatibilidade e para que ocorra a formação dos órgãos ectomicorrízicos. Neste trabalho são fornecidas evidências que sugerem a capacidade de extractos de raízes de castanheiro, nos estádios iniciais de contacto com P. tinctorius regularem o crescimento do fungo micorrízico

Competitive interactions between ectomycorrhizal and saprotrophic fungi on chestnut tree

In Northeast of Portugal the macrofungal community associated to chestnut tree (Castanea sativa is rich and diversified. Among fungal species, the ectomycorrhizal Pisolithus tínctorius and the saprotroph Hypholoma fasciculare are common in this habitat. The aim of the present work was to assess the effect of the interaction between both fungi on growth, nutritional status and physiology of C. satíva seedlings. In pot experiments, C. satíva seedlings were inoculated with P. tínctorius and H. fasciculare individually or in combination. Inoculation with P. tinctorius stimulated the plant growth and resulted in increased foliar-N, -P, and photosynthetic pigment contents. These effects were suppressed when H. fasciculare was simultaneously applied with P. tínctorius. This result could be related to the inhibition of ectomycorrhizal fungus root colonization as a result of antagonism or to the competition for nutrient sources. If chestnut seedlings have been previously inoculated with P. tinctorius, the subsequent inoculation of H. fasciculare 30 days later did not affect root colonization and mycorrhization benefits were observed. This work confirms an antagonistic interaction between ectomycorrhizal and saprotrophic fungi with consequences on the ectomycorrhizal host physiology. Although P. tinctorius is effective in promoting growth of host trees by establishing mycorrhizae, in the presence of other fungi it may not always be able to interact with host roots due to an inability to compete with certain fungi.This work has been supported by FCT (PTDC/ AGR-AAM/ 099556/2008)