Functional analysis of liverworts in dual symbiosis with Glomeromycota and Mucoromycotina fungi under a simulated Palaeozoic CO2 decline.

Most land plants form mutualistic associations with arbuscular mycorrhizal fungi of the Glomeromycota, but recent studies have found that ancient plant lineages form mutualisms with Mucoromycotina fungi. Simultaneous associations with both fungal lineages have now been found in some plants, necessitating studies to understand the functional and evolutionary significance of these tripartite associations for the first time. We investigate the physiology and cytology of dual fungal symbioses in the early-diverging liverworts Allisonia and Neohodgsonia at modern and Palaeozoic-like elevated atmospheric CO2 concentrations under which they are thought to have evolved. We found enhanced carbon cost to liverworts with simultaneous Mucoromycotina and Glomeromycota associations, greater nutrient gain compared with those symbiotic with only one fungal group in previous experiments and contrasting responses to atmospheric CO2 among liverwort-fungal symbioses. In liverwort-Mucoromycotina symbioses, there is increased P-for-C and N-for-C exchange efficiency at 440 p.p.m. compared with 1500 p.p.m. CO2. In liverwort-Glomeromycota symbioses, P-for-C exchange is lower at ambient CO2 compared with elevated CO2. No characteristic cytologies of dual symbiosis were identified. We provide evidence of a distinct physiological niche for plant symbioses with Mucoromycotina fungi, giving novel insight into why dual symbioses with Mucoromycotina and Glomeromycota fungi persist to the present day.The ISME Journal advance online publication, 27 November 2015; doi:10.1038/ismej.2015.204

Multilingual Conceptual Access to Lexicon Based on Shared Orthography: An Ontology-Driven Study of Chinese and Japanese

In this paper we propose a model for ontology-driven conceptual access to multilingual lexicon taking advantage of the cognitive-conceptual structure of radical system embedded in shared orthography of Chinese and Japanese. Our proposal rely crucially on two facts. First, both Chinese and Japanese use Chinese characters (hanzi/kanji) in their orthography. Second, the Chinese character orthography is anchored on a system of radical parts which encodes basic concepts. Each character as an orthographic unit contains radicals which indicate the broad semantic class of the meaning of that unit. Our study utilizes the homomorphism between the Chinese hanzi and Japanese kanji systems, but goes beyond the character-to-character mapping of kanji-hanzi conversion, to identify bilingual word correspondences. We use bilingual dictionaries, including WordNets, to verify semantic relation between the cross-lingual pairs. These bilingual pairs are then mapped to ontology of characters structured according to the organization of the basic concepts of radicals. The conceptual structure of the radical ontology is proposed as the model for simultaneous conceptual access to both languages. A study based on words containing characters composed of the “口 (mouth)” radical is given to illustrate the proposal and the actual model. It is suggested that the proposed model has the conceptual robustness to be applied to other languages based on the fact that it works now for two typologically very different languages and that the model contains Generative Lexicon (GL)-like coercive links to account for a wide range of possible cross-lingual semantic relations.Department of Chinese and Bilingual Studie

Recovery of Extra-Radical Fungal Peptides Amenable for Shotgun Protein Profiling in Arbuscular Mycorrhizae

International audienceIn arbuscular mycorrhizal symbiosis, the belowground mycelium that develops into the soil, not only provides extensive pathways for nutrient fluxes, the occupation of different niches, and dispersal of propagules, but also has strong influences upon biogeochemical cycling. By providing a valuable overview of expression changes of most proteins, shotgun proteomics can help decipher key metabolic pathways involved in the functioning of fungal mycelia. In this protocol, we describe the combination of extra-radical mycelium growth systems with gel-based extraction of fungal peptides amenable for shotgun protein profiling, which allows gaining information about the extra-radical proteom

Role of plant–fungal nutrient trading and host control in determining the competitive success of ectomycorrhizal fungi

Multiple ectomycorrhizal fungi (EMF) compete to colonise the roots of a host plant, but it is not known whether their success is under plant or fungal control, or a combination of both. We assessed whether plants control EMF colonisation by preferentially allocating more carbon to more beneficial partners in terms of nitrogen supply or if other factors drive competitive success. We combined stable isotope labelling and RNA-sequencing approaches to characterise nutrient exchange between the plant host Eucalyptus grandis and three Pisolithus isolates when growing alone and when competing either indirectly (with a physical barrier) or directly. Overall, we found that nitrogen provision to the plant does not explain the amount of carbon that an isolate receives nor the number of roots that it colonises. Differences in nutrient exchange among isolates were related to differences in expression of key fungal and plant nitrogen and carbon transporter genes. When given a choice of partners, the plant was able to limit colonisation by the least cooperative isolate. This was not explained by a reduction in allocated carbon. Instead, our results suggest that partner choice in EMF could operate through the upregulation of defence-related genes against those fungi providing fewer nutrients