Frequency distribution displaying a) the number of mycorrhizal OTUs and b) the number of sequences across the different fungal genera that were detected on the roots of <i>Platanthera bifolia</i>, <i>P</i>. <i>chlorantha</i> and individuals displaying intermediate characteristics.

<p>Frequency distribution displaying a) the number of mycorrhizal OTUs and b) the number of sequences across the different fungal genera that were detected on the roots of <i>Platanthera bifolia</i>, <i>P</i>. <i>chlorantha</i> and individuals displaying intermediate characteristics.</p

Mycorrhizal Fungal Diversity and Community Composition in Two Closely Related <i>Platanthera</i> (Orchidaceae) Species

<div><p>While it is generally acknowledged that orchid species rely on mycorrhizal fungi for completion of their life cycle, little is yet known about how mycorrhizal fungal diversity and community composition vary within and between closely related orchid taxa. In this study, we used 454 amplicon pyrosequencing to investigate variation in mycorrhizal communities between pure (allopatric) and mixed (sympatric) populations of two closely related <i>Platanthera</i> species (<i>Platanthera bifolia</i> and <i>P</i>. <i>chlorantha</i>) and putative hybrids. Consistent with previous research, the two species primarily associated primarily with members of the Ceratobasidiaceae and, to a lesser extent, with members of the Sebacinales and Tulasnellaceae. In addition, a large number of ectomycorrhizal fungi belonging to various families were observed. Although a considerable number of mycorrhizal fungi were common to both species, the fungal communities were significantly different between the two species. Individuals with intermediate morphology showed communities similar to <i>P</i>. <i>bifolia</i>, confirming previous results based on the genetic architecture and fragrance composition that putative hybrids essentially belonged to one of the parental species (<i>P</i>. <i>bifolia</i>). Differences in mycorrhizal communities between species were smaller in mixed populations than between pure populations, suggesting that variation in mycorrhizal communities was largely controlled by local environmental conditions. The small differences in mycorrhizal communities in mixed populations suggests that mycorrhizal fungi are most likely not directly involved in maintaining species boundaries between the two <i>Platanthera</i> species. However, seed germination experiments are needed to unambiguously assess the contribution of mycorrhizal divergence to reproductive isolation.</p></div

Number of plants sampled in the different populations, with characteristics of the soil at each site.

<p>Number of plants sampled in the different populations, with characteristics of the soil at each site.</p

Glycosaminoglycan mimetics obtained by microwave-assisted sulfation of marine bacterium sourced infernan exopolysaccharide

International audienceSulfated glycosaminoglycans (GAGs) are fundamental constituents of both the cell surface and extracellular matrix. By playing a key role in cell-cell and cell-matri x interactions, GAGs are involved in many physiological and pathological processes. To design GAG mimetics with similar therapeutic potential as the natural ones, the specific structural features, among them sulfate content, sulfation pattern, and chain length, should be considered. In the present study, we describe a sulfation method based on microwave radiation to obtain highly sulfated derivatives as GAG mimetics. The starting low-molecular-weight (LMW) derivative was prepared from the infernan exopolysaccharide, a highly branched naturally slightly sulfated heteropolysaccharide synthesized by the deep-sea hydrothermal vent bacterium Alteromonas infernus. LMW highly sulfated infernan derivatives obtained by conventional heating sulfation have already been shown to display GAG-mimetic properties. Here, the potential of microwave-assisted sulfation versus that of the conventional method to obtain GAG mimetics was explored. Structural analysis by NMR revealed that highly sulfated derivatives from the two methods shared similar structural features, emphasizing that microwave-assisted sulfation with a 12-fold shorter reaction time is as efficient as the classical one