Are cell wall arabinoxylans involved in desiccation tolerance of the South African resurrection grass Eragrostis nindensis

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Structural characterization of arabinoxylans from two African plant species Eragrostis nindensis and Eragrostis tef using various mass spectrometric methods

International audienceRATIONALE: The arabinoxylans are one of the main components of plant cell walls and are known to play major roles in plant tissues properties depending in particular on their structural features. It has been recently shown that one of the strategies developed by resurrection plants to overcome dehydration is based on cell wall composition. For this purpose, the structural characterization of arabinoxylans from desiccation-tolerant grass Eragrostis nindensis (E. nindensis) was compared with its close relative, the desiccation-sensitive Eragrostis tef (E. tef) in order to further understand mechansism of desiccation tolerance in resurrection plants. METHODS: Ion mobility spectrometry coupled to mass spectrometry (IM-MS) in combination with the conventional mass spectrometric approaches, including matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), electrospray ionization multistage tandem mass spectrometry (ESI-MSn) and gas chromatography/mass spectrometry (GC/MS), were used to characterize arabinoxylan fragments obtained after endo-xylanase digestion of leave extracts from E. nindensis and E. tef. RESULTSWhole fingerprinting by MALDI-MS analysis showed the presence of various arabinoxylan fragments within leaves of E. nindensis and E. tef. The monosaccharide composition and some linkage information were determined by GC/MS experiments. Information regarding the branching and sequence details was obtained by ESI-MSn experiments after sample permethylation. The presence of structural isomeric ions with different collision cross sections was evidenced by IM-MS which could be differentiated using ESI-MSn. CONCLUSIONS: We have shown that an orthogonal approach, and especially IM-MS associated to ESI-MSn (n=2 to 4) and GC/MS allowed characterization of arabinoxylan fragments of E. nindensis and E. tef and revealed the presence of isomeric structures. The same arabinoxylan structures were identified for both species but in different relative abundance. Moreover, this work illustrated that IM-MS can efficiently separate isomeric structures and advantageously complements the conventional mass spectrometric methodologies used for arabinoxylan structural characterization

Contributions to Arabinogalactan Protein Analysis

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Interactions of Nanoenabled Agrochemicals with Soil Microbiome

International audienceSoil is a dynamic, physically, spatially and temporally heterogeneous but well-organized, three-dimensional porous matrix mixing mineral and organic matter and living organisms. Among them, soil microbiota constitute a reservoir in which plants select a specific microbiome, contributing to their growth and their health. Microbes in soil also contribute to many ecosystemic services in agrosystems, as the recycling of major nutrients in the soil ecosystem (carbon, nitrogen, phosphorus, sulfur…). Nanoagrochemicals are active substances based on nanotechnologies and nanoformulations to improve the characteristics and properties of active molecules as pesticides for agronomy purposes, e.g., biocides, herbicides but also nutrients. Nanotechnologies have burst into agronomy with a potential for innovation in order to improve the efficiency of pesticides, nutrients, their delivery and thus contribute to the reduction of inputs in agriculture. However, the impact of these nanopesticides on the soil microbiota as non-target organism remains underestimated up to now. The chapter review the approaches and trends in the evaluation of nanopesticides implications on soil microbiota, focusing on copper-and silver-based nanoparticles as pesticides or on formulation or nanocarriers of conventional pesticides. By confronting the current knowledge and comparing methodologies, the potential and the pitfalls to overcome are discussed, together with future directions