31 research outputs found
Symbiosis: Herbivory Alters Mycorrhizal Nutrient Exchange
No full textA new study shows that a plant gives less carbon to its root-associated mycorrhizal fungus when targeted by herbivores, but the fungus doesn’t retaliate
Phylogenomics and the rise of the angiosperms
No full textAngiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods. A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome. Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins. However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes. This 15-fold increase in genus-level sampling relative to comparable nuclear studies provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade.NWOPlant sciencesNaturali
Fungi of the greening Arctic : compositional and functional shifts in response to climatic changes
No full text
The rate of climate warming in the Arctic nearly doubles warming in the temperate regions. In the arctic tundra, this warming has already altered vegetation, with strong declines in lichens and mosses and expansion of shrubs. This process called “the greening of the Arctic” has important consequences for the global nutrient cycling and emission of green-house gases to the atmosphere. Even though, plant community dynamics has been monitored in tundra, the effect of climate warming on belowground fungi remained largely unknown, despite the known key roles that fungi play providing the plants with water and nutrients in nutrient-poor arctic soils. This thesis addresses the effect of climate warming on arctic soil fungal communities by DNA-metabarcoding. Climate warming had a strong effect on fungal community composition leading to a strong decline in diversity of lichenized, moss-associated, and ectomycorrhizal fungi. Instead, many species of saprotrophic and parasitic fungi took over. These changes are expected to alter nutrient turnover in tundra soils (including decomposition and CO2 flux) and affect populations of plants and animals (for example, caribous that are feeding on lichenized fungi in winter).
NWO-ALW Open Program research grant (821.01.016)Naturali
Thismia (Thismiaceae): the first record of the mycoheterotrophic genus to the Flora of India with a new species revealing the phytogeographical significance of Western Ghats
No full textThismia, a genus of mycoheterotrophic plants, is reported for the first time from mainland India, from Neryamangalam forests in Idukki district of Kerala, along with a new species, T. sahyadrica. Thismia sahyadrica, described and illustrated here, is unique within Thismia in having a mitre with a single opening; five perianth lobes are fused into a mitre-like structure, while the sixth one is free, forming a lateral single opening of the flower. Due to its unique morphological characteristics, the taxonomic placement of the new species remains obscure, although some root and flower characters suggest an affinity with species from the sections Glaziocharis, Sarcosiphon, Geomitra, and Scaphiophora. Ecological specificity and phytogeographical peculiarities of the new species are also discussed
Mycoheterotrophic plants living on arbuscular mycorrhizal fungi are generally enriched in <sup>13</sup>C, <sup>15</sup>N and <sup>2</sup>H isotopes
No full text1. Fully mycoheterotrophic plants are thought to obtain carbon exclusively from their root-associated fungal partners. The general enrichment of these plants in the heavy isotopes 13C and 15N suggests that fungi are the main nutrient source for these plants. Yet, the majority of studies have targeted mycoheterotrophic plants associated with ectomycorrhizal, orchid mycorrhizal and saprotrophic fungi, while mycoheterotrophic plants living on arbuscular mycorrhizal fungi remain understudied.2. Here, we sampled 13 species of arbuscular mycorrhizal fully mycoheterotrophic plants from five families and co-occurring autotrophic reference plants growing in forests of tropical South America, tropical South East Asia and temperate Australasia. We measured stable isotope natural abundances (δ13C, δ15N, δ2H and δ18O), determined total nitrogen concentrations and used high-throughput DNA sequencing to characterize the arbuscular mycorrhizal fungal communities associated with the sampled mycoheterotrophic plants.3. We observed a general enrichment in 13C and 15N isotopes across mycoheterotrophic plant families and geographic regions. We confirm cases where no 15N enrichment is present, but we show that in general arbuscular mycoheterotrophic plants are enriched in 15N. Moreover, we demonstrate for the first time that these plants are significantly enriched in 2H but not in 18O in relation to their autotrophic references. The fungal communities targeted by the mycoheterotrophs mainly consist of Glomeraceae and show strong association with the isotopic signatures and geographic origin of the plants.4. Synthesis. Our findings enlarge the limited knowledge on the multi-element stable isotopic signatures of mycoheterotrophic plants living on arbuscular mycorrhizal fungi. We show that these plants are enriched in 13C and 2H as expected due to their mycoheterotrophic nutrition, and that in general they are also enriched in 15N, despite some exceptions. Variation in stable isotope signatures is likely influenced by plant taxonomy, geography and fungal community composition.</p
Orchid mycorrhizal interactions: evolutionary trajectories and ecological variations
No full textThe mycorrhizal symbiosis is among the most widespread species interactions on Earth. This thesis focuses on orchid mycorrhiza, a unique mycorrhizal type that has caught scientists’ attention for centuries. By merging the concepts and approaches of molecular phylogenetics, microbial community ecology, and plant ecophysiology, this thesis provides an overview of the evolution and ecology of orchid mycorrhizal interactions from both the fungal and plant perspective, and from the global to the local scale. In this thesis, the variation in fungal associations in space and in time is a central topic, which was inferred by analyses on phylogenetic signals and variation in fungal community structure and also captured by empirical experiments using metabarcoding approaches and quantitative ddPCR. Based on the insights gained in this thesis and that of previous studies, this thesis proposes several directions for future studies to deepen our understanding of the evolution, ecophysiology, and molecular biology of mycorrhizal symbiosis, and thus to benefit orchid conservation and ecosystem restoration.</p
Antiquities of the rainforest: evolution of mycoheterotrophic angiosperms growing on Glomeromycota
No full textDit proefschrift behandelt de evolutie en biogeografie van een bijzondere groep plantensoorten die leven in associatie met schimmels. Deze planten zijn mycoheterotroof; ze hebben hun fotosynthese capaciteit verloren en verkrijgen hun koolstofverbindingen van de schimmels. Ik bestudeerde de enigmatische plantenfamilies Triuridaceae, Corsiaceae en het genus Epirixanthes (Polygalaceae). Een eerste hoofdstuk beschrijft de voorheen onduidelijke verwantschappen en de biogeografie van de Triuridaceae. De resultaten suggereren dat dit een zeer oude groep is, die in het Krijt is ontstaan in Afrika of Zuid-Amerika. In het tweede hoofdstuk concludeerde ik dat de Corsiaceae een oorsprong hebben in het oercontinent Gondwana en dat ze sterk verwant zijn aan de Campynemataceae in de orde van de lelies. Mijn studie van Epirixanthes toonde aan dat dit voorheen onderbestudeerde genus zeer gespecialiseerd is in vergelijking met haar zustergroep, het fotosynthetiserende genus Salomonia. In het laatste hoofdstuk bediscussieer ik de biogeografische geschiedenis van alle mycoheterotrofe bloemplanten. De resultaten wijzen uit dat deze planten in tropische regenwouden zijn ontstaan, waarbij de Zuidoost Aziatische vertegenwoordigers jonger zouden zijn dan de andere groepen. Doordat deze bijzondere planten veelal in bedreigde gebieden voorkomen, zijn ze hoogstwaarschijnlijk erg kwetsbaar.Alberta Mennega Stichting Schure-Beijerinck-Popping Fonds (nu KNAW Fonds Ecologie)Plant science
Arbuscular mycorrhizal interactions of mycoheterotrophic Thismia are more specialized than in autotrophic plants
No full textMetabarcoding read abundances of orchid mycorrhizal fungi are correlated to copy numbers estimated using ddPCR
No full textEnvironmental Biolog
