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Arbuscular mycorrhizal fungi (AMF) form symbiotic associations with the majority of land plants and deliver a wide range of soil-based ecosystem services. Due to their conspicuous belowground lifestyle in a dark environment surrounded by soil particles, much is still to be learned about the influence of environmental (i.e., physical) cues on spore germination, hyphal morphogenesis and anastomosis/hyphal healing mechanisms. To fill existing gaps in AMF knowledge, we developed a new microfluidic platform – the AMF-SporeChip – to visualise the foraging behaviour of germinating Rhizophagus and Gigaspora spores and confront asymbiotic hyphae with physical obstacles. In combination with timelapse microscopy, the fungi could be examined at the cellular level and in real-time. The AMF-SporeChip allowed us to acquire movies with unprecedented visual clarity and therefore identify various exploration strategies of AMF asymbiotic hyphae. We witnessed tip-to-tip and tip-to-side hyphal anastomosis formation. Anastomosis involved directed hyphal growth in a “stop-and-go” manner, yielding visual evidence of pre-anastomosis signalling and decision-making. Remarkably, we also revealed a so-far undescribed reversible cytoplasmic retraction, including the formation of up to 8 septa upon retraction, as part of a highly dynamic space navigation, probably evolved to optimise foraging efficiency. Our findings demonstrated how AMF employ an intricate mechanism of space searching, involving reversible cytoplasmic retraction, branching and directional changes. In turn, the AMF-SporeChip is expected to open many future frontiers for AMF research.

Using capture fishery-derived fish oil and fishmeal in aquafeeds is unsustainable. This study mimicked semi-intensive shrimp ponds, including primary producers, in mesocosm tanks. Fatty acid mass balances were computed to distinguish between diet-based and primary production-based LC-PUFA contributions to shrimp (Litopenaeus vannamei) production and meat quality. Performance and body fatty acid composition were compared of shrimp fed a commercial diet containing fish oil and fishmeal (control), with a fishmeal- and fish oil-free diet (low LC-PUFA diet: LOW). Six mesocosms were each stocked with 60 juvenile shrimp and randomly assigned to the two diets. After an 8-week grow-out period, biomass production, survival and proximate body composition were similar between diets. Control shrimp contained twice as much LC-PUFA and omega-3 fatty acids than LOW shrimp. Large quantitative losses (85%) were found in both treatments of the LC-PUFA-precursors alpha-linolenic acid (ALA) and linoleic acid (LA) that were being used as energy source by the shrimp instead for LC-PUFA synthesis. Whereas losses were also observed for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the control group, there was a gain for these components in the LOW tanks. LOW shrimp sourced at least 32% of their total EPA gain and 15% of their total DHA gain from the algal-based food web. This quantitative analysis of the fate of major dietary fatty acids strongly suggests that the pond's primary production can provide shrimp additional LC-PUFA. Finding a balance between LC-PUFA contribution through formulated feed and natural production seems possible and deserves further research.

The use of plants containing naphthoquinone derivatives Alkannins & Shikonins (A/S) by humans dates back to ancient times. In recent decades, the use of A/S has seen a resurgence and A/S have risen to a pivotal role as pharmaceutical and cosmeceutical agents, since they possess strong wound healing, antimicrobial, anti-inflammatory, tissue regenerative and antitumor properties. It is thus crucial to enhance the biosynthesis of bioactive A/S in Alkanna tinctoria plants, that naturally produce high amounts of these metabolites [1]. In the frame of “MICROMETABOLITE” EU H2020 project, we have optimized a workflow for the metabolic profiling of A. tinctoria roots, cultured in the greenhouse from plants obtained by in vivo shoot cuttings. A fast and reliable extraction procedure was achieved for comprehensive profiling and identification of A/S and other metabolites biosynthesized in the roots. The aim of this work was to determine the growth stage with peak A/S production, while simultaneously obtaining additional information on the root metabolome. A combination of UHPLC-HRMS and NMR was used for metabolite identification, HPLC was utilized for reliable quantitation of A/S and the extracts were subjected to chiral HPLC analysis [2] for determination of the enantiomeric A/S ratio. Different A/S derivatives and other metabolites were identified in plant roots using UHPLC-HRMS and NMR. Six A/S derivatives and total A/S were quantified using HPLC-DAD. From six vegetation stages of A. tinctoria grown under greenhouse conditions, fruiting period was found to peak A/S production (1% wt/wt of root), while the enantiomeric alkannin/shikonin ratio remained constant (93.7%).

Arbuscular mycorrhizal fungi (AMF) are biotrophe microorganisms that establish a symbiotic association with host-plants. These plant-dependent microorganisms have already shown their strong effects concerning plant growth promotion and were reported to stimulate the secondary metabolites (SM) production of their host-plant. In this study, Anchusa officinalis plants, well-known for their therapeutic properties, were analyzed to assess the AMF effects on SM production. Two different experiments were developed on a semi-hydroponic system to compare treated A. officinalis plants with different AMF. In the first investigation, plants were inoculated with Rhizophagus irregularis, cultivated for 30 days and harvested two times. Concerning the second experiment, four different strains of AMF (R. clarus, R. intraradices, R. irregularis and Glomus aggretum) were tested separately on plants and one sampling was performed after one week. Roots and shoots were separated, lyophilized, ground and extracted using ultrasounds with EtOAc and MeOH (35:65 v/v) at 25°C. After centrifugation, the supernatants were removed and evaporated to dryness. Samples were analyzed with UHPLC-HRMS as well as HPTLC and HPLC-DAD-ELSD. Preliminary results of a targeted metabolomic analysis, showed that the concentration of main compound, rosmarinic acid, present in all the treated plants had no statistically difference from the controls. However, a discernable up-regulation and down-regulation of specific minor SMs in colonized plants was observed, suggesting that the aforementioned AMF affect specific biosynthetic pathways. Further experiments and analyses is needed but the cultivation of medicinal plants with AMF looks a promising way to enhance bioactive metabolites with applications in pharmaceutical and cosmeceutical industry.