Browsing by Author "Lino-Neto, Teresa"
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- Bacteria could help ectomycorrhizae establishment under climate variationsPublication . Reis, Francisca; Magalhães, Alexandre P.; Tavares, Rui Manuel; Baptista, Paula; Lino-Neto, TeresaRhizosphere microbiome is one of the main sources of plant protection against drought. Beneficial symbiotic microorganisms, such as ectomycorrhizal fungi (ECMF) and mycorrhiza helper bacteria (MHB), interact with each other for increasing or maintaining host plant fitness. This mutual support benefits all three partners and comprises a natural system for drought acclimation in plants. Cork oak (Quercus suber L.) tolerance to drought scenarios is widely known, but adaptation to climate changes has been a challenge for forest sustainability protection. In this work, ECMF and MHB communities from cork oak forests were cross-linked and correlated with climates. Cenococcum, Russula and Tuber were the most abundant ECMF capable of interacting with MHB (ECMF~MHB) genera in cork oak stands, while Bacillus, Burkholderia and Streptomyces were the most conspicuous MHB. Integrating all microbial data, two consortia Lactarius/Bacillaceae and Russula/Burkholderaceae have singled out but revealed a negative interaction with each other. Russula/Burkholderaceae might have an important role for cork oak forest sustainability in arid environments, which will be complemented by the lower drought adaptation of competitive Lactarius/Bacillaceae. These microbial consortia could play an essential role on cork oak forest resilience to upcoming climatic changes.
- Bacterial disease induced changes in fungal communities of olive tree twigs depend on host genotypePublication . Gomes, Teresa; Pereira, J.A.; Lino-Neto, Teresa; Bennett, Alison E.; Baptista, PaulaIn nature, pathogens live and interact with other microorganisms on plant tissues. Yet, the research area exploring interactions between bacteria-fungi and microbiota-plants, within the context of a pathobiome, is still scarce. In this study, the impact of olive knot (OK) disease caused by the bacteria Pseudomonas savastanoi pv. savastanoi (Psv) on the epiphytic and endophytic fungal communities of olive tree twigs from three different cultivars, was investigated in field conditions. The ITS-DNA sequencing of cultivable fungi, showed that OK disease disturbs the resident fungal communities, which may reflect changes in the habitat caused by Psv. In particular, a reduction on epiphyte abundance and diversity, and changes on their composition were observed. Compared to epiphytes, endophytes were less sensitive to OK, but their abundance, in particular of potential pathogens, was increased in plants with OK disease. Host genotype, at cultivar level, contributed to plant fungal assembly particularly upon disease establishment. Therefore, besides fungi - Psv interactions, the combination of cultivar - Psv also appeared to be critical for the composition of fungal communities in olive knots. Specific fungal OTUs were associated to the presence and absence of disease, and their role in the promotion or suppression of OK disease should be studied in the future.
- Bacterial dynamics and exchange in plant-insect interactionsPublication . Cameirão, Cristina; Pereira, José Alberto; Tavares, Rui; Lino-Neto, Teresa; Baptista, PaulaIn nature, plants and insects engage in intricate interactions. Despite the increasing knowledge of the microbiomes of plants and insects, the extent to which they exchange and alter each other’s microbiomes remains unclear. In this work, the bacterial community associated with nymphs of Philaenus spumarius (Hemiptera: Aphrophoridae), the stems of Coleostephus myconis where the nymphs were feeding, and the foam produced by the nymphs, were studied by culture-dependent and -independent approaches, with an attempt to elucidate the exchange of bacteria between plants and insects. The results suggest that both approaches complement each other, as many bacterial genera identified by metabarcoding were not detected by culturing, and vice versa. Overall, stems and foam exhibited higher bacterial diversity than nymphs, with all the samples showing enrichment in bacteria known to provide diverse benefits to their host. Stems and foam were the most similar in bacterial composition, but Burkholderiaceae and Moraxellaceae dominated the stems, whereas Rhizobiaceae and Sphingobacteriaceae dominated the foam. Nymphs exhibit the most distinct bacterial composition, yet more similar to that found in the stem compared to the foam. Indeed, nymphs were enriched on endosymbiotic bacteria, mostly Candidatus Sulcia and Sodalis, not found in the stem and foam. Nevertheless, during feeding, nymphs appeared to exchange several bacteria genera with C. myconis, with a significant number being incor- porated into the bacteriome of the nymph. The genera Curvibacter, Cutibacterium, Methylobacterium, Pseudomonas and Rhizobium are likely the most exchanged. Nymphs also appear to exchange bacteria to the foam, notably species from the Enhydrobacter, Pseudomonas, Rhizobium and Roseomonas genera. More studies to infer the functions of the shared bacteria between P. spumarius-C. myconis are needed.
- Beauveria bassiana, fungo entomopatogénico da traça-da-oliveira em Trás-os-Montes: caracterização morfológica e molecular.Publication . Baptista, Paula; Coelho, Valentim; Bento, Albino; Lino-Neto, Teresa; Pereira, J.A.A traça-da-oliveira, Prays oleae (Bern.), é uma praga chave da oliveira na região de Trás-os-Montes. Uma possível alternativa à luta química contra esta praga, reside na utilização de fungos entomopatogénicos (FE). Contudo, a presença e expressão destes fungos em Portugal é praticamente desconhecida. Recentemente Introdução e objectivos foi efectuado o isolamento in vitro de fungos, associados a pupas de traça-da-oliveira parasitadas, provenientes de olivais localizados na região de Trás-os-Montes. No presente trabalho pretendeu-se caracterizar morfologicamente e molecularmente um dos isolados obtidos – Beauveria bassiana.
- Beauveria bassiana, fungo entomopatogénico da traça-da-oliveira em Trás-os-Montes: caracterização morfológica e molecular.Publication . Baptista, Paula; Coelho, Valentim; Bento, Albino; Lino-Neto, Teresa; Pereira, J.A.A traça-da- olivelra, Prays oleoe (Bern.), é uma praga chave da oliveira na região de Trás- os-Montes. Uma possível alternativa a luta química contra esta praga, reside na utilização de fungos entomopatogénicos (FE). Dado o desconhecimento da presença e expressão destes fungos em Portugal foi recentemente efectuado o isolamento in vitro de fungos, associados a pupas de traça-da-oliveira parasitadas, provenientes de olivais localizados na região de Trás- os-Montes. No presente trabalho pretendeu-se caracterizar morfologicamente e molecularmente um dos isolados obtidos.
- Biological control of Pseudomonas savastanoi pv. savastanoi by two bacterial isolated from olive tree phyllospherePublication . Diogo, Mina; Santos, Alba; Pereira, J.A.; Lino-Neto, Teresa; Baptista, PaulaOlive knot disease, caused by the bacterium Pseudomonas savastanoi pv. savastanoi (Psv), has been responsible for high economical crop losses in olive orchards, especially in Mediterranean countries. Olive knot cannot be eradicated once it is established in an orchard, and therefore its control is based on preventive measures. Laboratory experiments previously performed by us have showed the capacity of some bacterial species, isolated from olive tree phyllosphere, to inhibited Psv growth. In the present work, the two most promising bacterial isolates (i.e. Frondihabitans sp. and Paenibacillus sp.) were evaluated for the control of Psv in olive plantlets (Olea europaea L.) under greenhouse conditions, to predict their effect in a more natural condition. In pot experiments, two-year-old olive plants cv. Cobrançosa were inoculated with the antagonistic bacteria and Psv individually or in combination. Inoculations were performed in wounds previously made in three different sites of the main stem. Thirty replicate plants were used per strain. The plants were observed for symptom development and the number of bacteria on the inoculation sites was periodically evaluated, for up to 120 days after inoculation. To quantify the reduction of symptom expression, knots were excised from stems and their weights were compared between treatments. Inoculation with Psv resulted in the formation of knots with significantly higher weight values compared to plants inoculated simultaneously with Psv and antagonistic bacteria. Both tested bacterial also showed the capacity to reduce the amount of Psv in the inoculation sites, suggesting their effectiveness in controlling the multiplication of the pathogen. Data presented here demonstrate for the first time the potential of these bacteria for suppression of olive knot, and these two species should be considered in the future as potential biocontrol agents against Psv.
- Biological potential of fungi associated to Prays oleae in Trás-os-Montes (Northeastern region of Portugal)Publication . Oliveira, Ivo; Baptista, Paula; Lino-Neto, Teresa; Bento, Albino; Pereira, J.A.Olive groves represent an important fraction of the agricultural practices in Portugal, mainly in the region of Trás-os-Montes. Our work pretends to disclose the fungal diversity associated to one of the major olives pests, the Prays oleae Bern. Besides evaluating the extent of the presence of entomopathogenic fungi, we also intend to reveal other promising fungi with potential to be used as biological control agents. In order to achieve this goal, larvae and pupae of the three generations of P.oleae were collected from several orchards. Whenever a fungal agent was associated to the cause of death, we proceeded to the preparation of fungal pure cultures, DNA isolation, amplification and sequencing of their ITS region for species identification. High fungal diversity was found, with the majority of the fungi presenting simultaneously entomopathogenic, antagonistic or phytopathogenic characteristics. 22 different species were identified, being Beauveria bassiana, a well-known entomopathogen, the most frequently isolated fungi. The ones described as antagonistic were tested in dual cultures for antagonistic activity against phytopathogenic fungi.
- Caracterização do sistema antioxidativo no estabelecimento da associação micorrízica Castanea sativa Mill. / Amanita muscariaPublication . Baptista, Paula; Martins, Anabela; Tavares, Rui Manuel; Lino-Neto, TeresaAs micorrizas são associações mutualistas que se estabelecem entre fungos, pertencentes sobretudo às divisões Basidiomycota, Ascomycota e Zigomycota, e raízes de plantas vasculares. Com o estabelecimento da associação micorrízica, ocorrem várias alterações morfológicas, fisiológicas e ecológicas em ambos os intervenientes, que têm sido objecto de estudo por diversos autores. Contudo, os mecanismos que controlam o processo de colonização e como este processo se inicia é completamente desconhecido. Os poucos trabalhos desenvolvidos nesta área, utilizando micorrizas arbusculares, sugerem que, durante as primeiras horas de invasão do fungo, ocorre uma indução de resposta de defesa por parte da planta hospedeira, semelhante à observada na interacção planta-patogénio. O presente trabalho pretende averiguar o efeito da inoculação de plantas de Castanea sativa Mill. com o fungo ectomicorrízico Amanita muscaria, na indução de resposta de defesa da planta hospedeira.O trabalho experimental decorreu num sistema in vitro estabelecido entre plantas de C. sativa e o fungo A. muscaria. Durante as primeiras horas de contacto (0 às 48 horas) procedeu-se à recolha de amostras de raízes, caules e folhas da planta hospedeira e de micélio de fungo que esteve em contacto com a raiz. Nestas amostras analisaram-se os níveis de peróxido de hidrogénio (H2O2), a actividade da catalase (CAT) (EC 1.11.1.6) e da superóxido dismutase (SOD) (EC 1.15.1.1). Os resultados obtidos evidenciam três picos de produção de H2O2, sugerindo o seu possível envolvimento no estabelecimento de micorrizas, nas primeiras horas de contacto planta-fungo. As variações observadas na actividade da SOD e da CAT, indiciam o seu envolvimento no controlo dos níveis de H2O2 em raízes, permitindo que esta molécula possa actuar como molécula sinalizadora, mas evitando que os níveis se tornem nocivos para o sistema. Estes resultados, apesar de preliminares, reflectem uma condição de stresse oxidativo semelhante àquela observada em interacções plantapatogénio, durante as primeiras horas de contacto.
- Characterization of the oxidative system on Castanea sativa Mill. in association with the ectomycorrhizal fungi Pisolithus tinctorius and Amanita muscaria during the early stages of contactPublication . Baptista, Paula; Martins, Anabela; Tavares, Rui Manuel; Lino-Neto, TeresaMycorrhizae are symbiotic associations between soil borne fungi and the root system of higher plants having a beneficial role on plant growth. The fungus receives carbon from plant, while the plant increased nutrient uptake mediated via the fungus. In agroforestry systems, most of the mycorrhizae belong to ectomycorrhizal (ECM) group being the mechanisms controlling its development poorly defined. During arbuscular mycorrhizal (AM) establishment, some evidences suggest that a temporal and spatial activation of different defence mechanisms by plants are activated. The present work pretends to assess the influence of ECM inoculation on the activity of antioxidant enzymes from roots of Castanea sativa Mill., during the early stages of contact. The experimental work was carried out in an “in vitro” system, established between two symbiotic associations: Castanea sativa Mill. / Pisolithus tinctorius and Castanea sativa Mill. / Amanita muscaria. In these systems, plants were harvested at different times of fungi contact. The levels of H2O2 and the activity of oxidative stress enzymes, namely catalase (EC 1.11.1.6), superoxide dismutase (EC 1.15.1.1) and ascorbate peroxidase (EC 1.11.1.11), were determined in roots. The results suggest that in the early stages of plant-ECM fungi interaction the oxidative metabolism could be involved, in a similar way as described for plant-AM interactions, where the plants produce enzymatic as well as non-enzymatic defence responses. Preliminary results will be presented and discussed in order to understand the effect of ectomycorrhizal fungi contact on oxidative stress enzyme activities of the host.
- Climatic impacts on the bacterial community profiles of cork oak soilsPublication . Reis, Francisca; Soares-Castro, Pedro; Costa, Daniela; Tavares, Rui Manuel; Baptista, Paula; Santos, Pedro M.; Lino-Neto, TeresaClimate changes comprise increasing global temperature and water cycle deregulation (precipitation storms and long dry seasons). Many affected ecosystems are located within the Mediterranean basin, where cork oak (Quercus suber L.) is one of the most important forest ecosystems. Despite cork oak tolerance to drought, the decrease of water availability and increase of temperature is causing a serious decline of cork oak populations. In the present work, the bacterial community of cork oak soils was assessed by metabarcoding using Illumina Miseq. Soils from seven independent cork oak forests were collected along a climate gradient. In all forest soils, Proteobacteria and Actinobacteria were the richest and more abundant bacteria. Acidobacteria also presented a high relative abundance, and Chloroflexi was a rich phylum. The soil bacterial community diversity and composition was strongly affected by the climatic region where cork oak resides and specific bacterial taxa were differently affected by precipitation and temperature. Accordingly, cork oak bacterial communities clustered into three distinct groups, related with humid, sub-humid and arid/semi-arid climates. Driest and warmer forests presented more diverse bacterial communities than humid and coolest forests. However, driest climates presented more homogenous bacterial communities among forests than humid climates. Climate (mainly precipitation) revealed to be the strongest driver leading to significant variations of bacterial community profiles. The most impacted bacterial taxa by climatic variables were Proteobacteria, in particular Gammaproteobacteria and Deltaproteobacteria, Chloroflexi, and Firmicutes. Humid forests presented mainly Acidobacteria as good indicators of climate, whereas Actinobacteria members were better indicators for arid forests (mainly Gaiellales and Frankiales). Some indicator species for different climate conditions were members of the bacterial core of cork oak stands (7% of the total bacterial community). Taken together, different microbiomes were selected by the climate conditions in cork oak stands along a climate gradient and might provide the key to forest sustainability in times of global warming.