Potential Role of Native Arbuscular Mycorrhizal Fungi (AMF) in the Restoration of Laurisilva

The beneficial association of seedlings with arbuscular mycorrhizal fungi (AMF) is thought to improve early tree establishment through increased uptake of poorly labile soil nutrients (particularly P) and enhancing plant tolerance to biotic and abiotic factors. Seedlings of Juniperus brevifolia, an endemic woody plant of the Azores archipelago with potential commercial value, was grown in the nursery with and without inoculation by a commercial plant growth promoter consisting of AMF isolated from the Azores (MICOazorica). Treatments were arranged in a randomized complete block design in a greenhouse. At six months after planting, all AMF-inoculated plants were colonized. The percentage of colonization varied between 46% and 96% (Mean 70%). At harvest, all physical parameters were significantly greater in AMF-inoculated plants relative to uninoculated plants. Based on the obtained results, we strongly advise the use of native AMF, in strategies used in restoration programs in the Azores.This research was funded by Fundo Regional para a Ciênciae Tecnologia – Governo dos Açores (M3.1.a/F/059/2016).info:eu-repo/semantics/publishedVersio

Diversity and distribution of arbuscular mycorrhizal fungi along a land use gradient in Terceira Island (Azores)

More knowledge of community composition of arbuscular mycorrhizal (AM) fungi in ecosystems in relation to habitat type and land use intensity is needed. We studied AMF in 106 soil samples from pristine natural forests and a gradient of disturbance including semi-natural and intensively managed pastures of Terceira, Azores. Altogether, 42 spore morphotypes were detected from eight AMF families, revealing different fungal community structures among the three land use types. Spore density was highest in native forests and lowest in intensively managed pastures, but fungal richness was highest in semi-natural pastures and lowest in native forests. No significant difference occurred between intensively managed pastures and native forests. Members of Acaulosporaceae and Glomeraceae were dominant in native forests, while fungi from Gigasporaceae and Claroideoglomeraceae were most abundant in semi-natural and intensively managed pastures respectively, indicating family-based ecological preferences. Rarefaction analysis revealed that pastures supported more diverse AMF communities than native forests, because in high elevation pristine forests, a few rare species dominate. It is therefore likely that more species would be found with increasing survey effort. Further research is needed to clarify the influence of land use type on AMF diversity and distribution in remote islands, and the role of native AMF on soil ecosystem processes and the spread of exotic plants.This research was funded by Fundo Regional para a Ciência e Tecnologia–Governo dos Açores (M3.1.a/F/059/2016; M3.1.a/F/012/2016) and by the Development Grant (IF/00462/2013) from the Fundação para a Ciência e a Tecnologia (FCT) Portugal with national funds and co-funded by FEDER and COMPETE 2020 program. The Royal Botanic Garden Edinburgh (RBGE) is supported by the Scottish Government’s Rural and Environmental Science and Analytical Services Division.info:eu-repo/semantics/publishedVersio

Possíveis impactes das alterações climáticas nas pastagens dos Açores

Este livro apresenta os principais resultados do projeto PASTURCLIM, que decorreu em três pastagens da ilha Terceira. Recorrendo a câmaras de topo aberto (CTA), o objetivo foi simular o aumento da temperatura previsto durante este século, como resultado do aquecimento global, e avaliar os efeitos: (1) Na produtividade das pastagens, na qualidade da forragem e na disponibilidade de nutrientes do solo; (2) Na composição da comunidade de artrópodes, principalmente aracnídeos e insectos, associados às pastagens. Apesar de não estar nos objetivos iniciais do projeto, avaliámos ainda o efeito do aumento da temperatura na produção in vitro de metano.info:eu-repo/semantics/publishedVersio

Arbuscular mycorrhizal fungal diversity and composition in pastures of the Azores : assessing the impact of management practices

Tese de doutoramento em Biologia (Ecologia), apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.Arbuscular mycorrhizal fungi (AMF) are ubiquitous, underground, symbiotic associations involving a wide diversity of plants (approximately 80%) and obligate symbiotic fungi of the phylum Glomeromycota thought to have originated 400–500 million years ago. In this intimate association the obligate biotrophic fungi provide terrestrial plants with minerals, nutrients (particularly inorganic phosphate) and water increasing the host resistance to biotic and abiotic stresses, including pathogens, water limitation and environmental pollutants in return for photosynthates. Diversity of AMF is generally higher in natural and semi-natural systems than in more intensively managed agroecosystems, where it can be strongly reduced. The objective of this study was to investigate whether land use type can be characterized by their arbuscular mycorrhizal fungal (AMF) communities, and to test the potential effect of AMF indigenous as inoculants on crops productivity and host tolerance to root-knot Meloidogyne incognita. AMF community structure associated to Holcus lanatus L. root was studied during two years in two land uses: semi-natural (Pico do Galhardo- PX; Terra Brava- TB) and intensive (Agualva 1- RP1; Agualva 2- RP2) pastures of Terceira Island (Azores). The spore community composition of AMF associated to Holcus lanatus L. root was determined by taxonomic identification of AMF spores. Thirthy-nine AMF species representing eight genera were detected in the land uses studied. The most representative genera of AMF spore community were Glomus, Acaulospora and Scutellospora. Land use type had no significant effect on AMF spore diversity and total abundance. This also was confirmed by molecular methods (PCR-DGGE) on roots of H. lanatus. In Azorean pastureland the input of fertilisers is lower than average inputs to pastures on the European mainland, which presumably did not contribute to occurrence of an evident pattern of AMF diversity. However, the reverse was observed for colonisation of different AMF structures (arbuscules, vesicles and hyphae) on H. lanatus root, where the highest of AMF colonisation was in semi-natural use. Colonisation of different AMF structures on H. lanatus root showed a seasonal pattern between sampling dates. The higher abundance of AMF structures in the summer than in autumn/winter could be related to nutrient exchanges, host metabolic pathway, phenology and climatic variations. Striking differences were found in AMF spores composition between land uses. Species of Glomus were dominant in intensive land uses, while Acaulospora and Scutellospora predominated in semi-natural ones. Different strategies of colonisation among AMF and soil nutrient levels may be the most important factors influencing the AMF community. Members of Glomaceae have a highly infective extra-radical mycelium that could allow colonising immediately plant roots (early succession), while members of Gigasporaceae are only capable of propagation via spore dispersal, therefore colonize plant roots more slowly than members of Glomaceae. Both spore densities of Glomus, Acaulospora and Scutellospora genera, as well as root colonisation were related with soil nutrients (N, K, Mg, Ca, OM), but no correlation was found with soil phosphorus (P). Our results confirm that the degree of AMF benefit to a host plant depends on plant species. Lolium perenne L. was the most mycorrhizal dependent plant (DM= 62%), followed by Holcus lanatus L. (DM= 40%) which resulted in an increase of foliar biomass more than 30 % in both plant species caused by inoculation with native AMF. Conversely, Lolium multiflorum L. was the less mycorrhizal dependent (DM= 27%) plant and also the less colonised. In more than 90% of the samples, inoculation with the native AMF conferred protection to H. lanatus from the root-knot Meloidogyne incognita. Among the mechanism proposed to explain the protective effect of AMF, we suggest that plant growth promotion by AMF, and direct competition between AMF and the nematode for host colonisation sites and photosynthates were involved. We conclude that: either AMF spore diversity or AMF diversity on H. lanatus root were independent of land use intensity; However, in the intensive management regime, there was a trend to an increased incidence of certain AMF, especially from the Glomus indicating a potentially severe loss of ecosystem functions under this land use type; colonisation of different AMF structures was higher in semi-natural land use and showed a marked seasonal pattern, dependent of plant phenology and metabolic pathway and climatic conditions. Inoculation with indigenous AMF significantly increased plant productivity and tolerance to root-knot M. incognita, but degree of AMF benefit to a host plant varies in function of plant species. Thus, AMF may play an important role in ecosystems functioning, since their appropriate management can reduce the use of chemical and energy in agriculture and consequently lead to more economical and sustainable production systems.Os fungos micorrízicos arbusculares (FMA) são associações simbióticas envolvendo uma ampla diversidade de plantas (aproximadamente 80%), e fungos simbiontes obrigatórios do filo Glomeromycota cuja origem estima-se ter ocorrido há 400-500 milhões de anos. Nesta íntima associação o fungo biotrófico obrigatório supre a planta com minerais, nutrientes (particularmente fosfato inorgânico) e água, aumentando deste modo, a resistência da planta hospedeira a stresses bióticos e abióticos, incluindo agentes patogénicos, stress hidríco e poluentes ambientais em troca de produtos fotossíntetizados. A diversidade de FMA é geralmente mais elevada em sistemas naturais e semi-naturais do que em agro-ecossistemas mais intensivos, onde poderá ser fortemente reduzida. O objectivo deste estudo foi investigar se as comunidades de fungos micorrízicos poderão servir de ferramentas na caracterização do tipo de maneio do solo, e testar o potencial efeito da inoculação com fungos nativos na produtividade das culturas, bem como na sua tolerância a nemátodes formadores de galhas - Meloidogyne incognita. A estrutura da comunidade micorrízica associada às raízes de Holcus lanatus L. foi estudada durante dois anos em dois sistemas de uso do solo: pastagens seminaturais (Pico do Galhardo- PX; Terra Brava- TB) e intensivas (Agualva 1- RP1; Agualva 2- RP2) da ilha Terceira (Açores). A composição da comunidade de FMA associada a H. lanatus foi determinada tendo em conta as características morfológicas dos esporos de FMA. Nos dois sistemas de maneio do solo foram detectadas 39 espécies de FMA distribuídas por 8 géneros. Os géneros mais representativos foram Glomus, Acaulospora e Scutellospora. A diversidade de esporos de FMA, assim como, a sua abundância não foi afectada pelo tipo de maneio do solo. Este resultado também foi confirmado por via molecular (PCR-DGGE), em relação à diversidade de espécies da comunidade fúngica nas raízes de H. lanatus. Os níveis de fertilizantes aplicados nas pastagens açorianas são em média muito mais baixos, do que os aplicados em pastagens do continente Europeu, o que presumivelmente não terá contribuído para a obtenção de um evidente padrão de diversidade micorrízica. Contudo, a quantificação da colonização das diferentes estruturas micorrízicas (arbúsculos, vesículas e hifas) exibiu o padrão diferente, tendo sido mais elevada nas pastagens semi-naturais do que nas intensivas. Além disso, as diferentes estruturas micorrízicas exibiram um marcado padrão sazonal entre épocas de amostragem, tendo sido mais abundantes durante o Verão do que no Outono/Inverno. Este facto, poderá estar relacionado com as trocas de nutrientes, a via metabólica do carbono da planta hospedeira, o estado fenológico e com as variações climáticas. Foram encontradas profundas diferenças na composição de espécies entre os dois sistemas de uso do solo. Nos sistemas semi-naturais os géneros mais representativos foram Acaulospora e Scutellospora, enquanto nos intensivos dominaram as espécies pertencentes ao género Glomus. O tipo de estratégia de colonização adoptado pelos diferentes FMA, bem como, os níveis de nutrientes do solo, poderão ser os principais factores responsáveis por essas diferenças na comunidade micorrízica. Os membros da família Glomeraceae possuem um micélio extra-radicular altamente infectivo que lhes permite uma rápida colonização radicular, enquanto os membros da família Gigasporaceae, visto serem apenas capazes de se propagarem via dispersão dos esporos apresentam uma taxa de colonização mais lenta. A densidade de esporos dos géneros Glomus, Acaulospora e Scutellospora assim como, a colonização radicular estiveram correlacionados com o nível de nutrientes do solo (N, K, Mg, Ca, MO), excepto com o fósforo (P). Os nossos resultados confirmam que, os benefícios resultantes da relação simbiótica dependem da espécie de planta hospedeira. Lolium perenne L. foi a planta que exibiu maior dependência micorrízica (DM= 62%) seguida de Holcus lanatus L. (DM= 40%), o que originou um incremento na biomassa foliar superior a 30 % em ambas as espécies de plantas. Contrariamente, Lolium multiflorum Lam. foi a espécie de planta com menor percentagem de colonização micorrizica, e por conseguinte a menos dependente da micorrização (DM= 27%). A inoculação com FMA nativos aumentou a tolerância de H. lanatus à infecção por Meloidogyne incognita em mais de 90 % das amostras. Entre os vários mecanismos propostos para explicar o efeito protector dos FMA, destaca-se o aumento no vigor da planta resultante da colonização micorrízica, e a competição por espaço e compostos fotossíntetizados que se estabelece entre o FMA e o nemátode. Com base neste estudo podemos concluir que: quer a diversidade de esporos de FMA, como a diversidade de FMA que colonizam as raízes de H. lanatus não dependem da intensidade do sistema de maneio; no entanto, nos sistemas intensivos há uma tendência para uma maior ocorrência de certos FMA, especialmente os pertencentes ao género Glomus, assistindo-se por conseguinte a uma potencial perda da funcionalidade dos ecossistemas neste tipo de maneio do solo; a colonização das diferentes estruturas micorrízicas foi mais elevada nas pastagens semi-naturais, e exibiu uma marca sazonalidade relacionada com a fenologia e metabolismo de carbono da planta hospedeira, e com as condições climáticas. A inoculação com FMA nativos aumentou significativamente a produtividade das plantas e tolerância à infecção por nemátodos galhadores – M. incógnita, mas todavia depende da especificidade da planta hospedeira. Deste modo, os FMA poderão desempenhar um papel importante na funcionalidade dos ecossistemas, uma vez que o seu uso adequado poderá reduzir a aplicação de produtos químicos, bem como, os custos energéticos na agricultura e consequentemente conduzir a uma agricultura mais sustentável e económica

Distribution of arbuscular mycorrhizal fungi (AMF) in Terceira and São Miguel Islands (Azores)

The data, presented here, come from samples collected during three research projects which aimed to assess the impact of land-use type on Arbuscular Mycorrhizal Fungi (AMF) diversity and community composition in pastures of Terceira Island (Azores, Macaronesia, Portugal) and also in the native forest of two Azorean Islands (Terceira and São Miguel; Azores, Macaronesia, Portugal). Both projects contributed to improving the knowledge of AMF community structure at both local and regional scales. Little is known on the AMF communities from Azores islands and this study reports the first survey in two Azorean Islands (Terceira and São Miguel). A total of 18,733 glomeromycotan spores were classified at the species level from 244 field soil samples collected in three different habitat types – native forests (dominated by Juniperus brevifolia and Picconia azorica), semi-natural and intensively-managed pastures. Thirty-seven distinct spore morphotypes, representing ten glomeromycotan families, were detected. Species of the family Acaulosporaceae dominated the samples, with 13 species (38% of the taxa), followed by Glomeraceae (6 spp.), Diversisporaceae (4 spp.), Archaeosporaceae (3 spp.), Claroideoglomeraceae (3 spp.), Gigasporaceae (3 spp.), Ambisporaceae and Paraglomeraceae, both with the same number of AMF species (2 spp.), Sacculosporaceae (1 sp.) and Entrophospora (family insertae sedis). Members of the family Acaulosporaceae occurred almost exclusively in the native forests especially associated with the Picconia azorica rhizosphere, while members of Gigasporaceae family showed a high tendency to occupy the semi-natural pastures and the native forests of Picconia azorica. Members of Glomeraceae family were broadly distributed by all types of habitat which confirm the high ecological plasticity of this AMF family to occupy the more diverse habitats

Varenicline for cognitive impairment in people with schizophrenia: systematic review and meta-analysis

Background People with schizophrenia frequently have cognitive dysfunction, which does not respond to pharmacological interventions. Varenicline has been identified as a potential treatment option for nicotinic receptor dysfunction with a potential to treat cognitive impairment in schizophrenia. Methods We conducted a systematic review of Pubmed, Embase, Psycinfo, CINAHL and the Cochrane Schizophrenia Trial Registry for randomised controlled trials of varenicline in people with schizophrenia for cognitive dysfunction. We excluded trials among people with dementia. We then undertook a meta-analysis with the primary outcome of difference in change of cognitive measures between varenicline and placebo as well as secondary outcomes of difference in rates of adverse events. We conducted a sensitivity analysis on smoking status and study duration. Results We included four papers in the meta-analysis (n = 339). Varenicline was not superior to placebo for overall cognition (SMD = -0.022, 95% CI -0.154-0.110; Z = -0.333; p = 0.739), attention (SMD = -0.047, 95% CI -0.199-0.104; Z = -0.613; p = 0.540), executive function (SMD = -0.060, 95% CI -0.469-0.348; Z =- 0.290; p = 0.772) or processing speed (SMD = 0.038, 95% CI -0.232-0.308; Z = 0.279; p = 0.780). There was no difference in psychotic symptoms, but varenicline was associated with higher rates of nausea. Sensitivity analyses for smoking status and study duration did not alter the results. Conclusion Within the present literature, varenicline does not appear to be a useful target compound for improving cognitive impairment in schizophrenia. Based on these results, a trial would need over 2500 participants to be powered to show statistically significant findings

Microbial island biogeography: Isolation shapes the life history characteristics but not diversity of root-symbiotic fungal communities

Island biogeography theory is one of the most influential paradigms in ecology. That island characteristics, including remoteness, can profoundly modulate biological diversity has been borne out by studies of animals and plants. By contrast, the processes influencing microbial diversity in island systems remain largely undetermined. We sequenced arbuscular mycorrhizal (AM) fungal DNA from plant roots collected on 13 islands worldwide and compared AM fungal diversity on islands with existing data from mainland sites. AM fungal communities on islands (even those >6000 km from the closest mainland) comprised few endemic taxa and were as diverse as mainland communities. Thus, in contrast to patterns recorded among macro-organisms, efficient dispersal appears to outweigh the effects of taxogenesis and extinction in regulating AM fungal diversity on islands. Nonetheless, AM fungal communities on more distant islands comprised a higher proportion of previously cultured and large-spored taxa, indicating that dispersal may be human-mediated or require tolerance of significant environmental stress, such as exposure to sunlight or high salinity. The processes driving large-scale patterns of microbial diversity are a key consideration for attempts to conserve and restore functioning ecosystems in this era of rapid global change