Strong increase of durum wheat iron and zinc content by field-inoculation with arbuscular mycorrhizal fungi at different soil nitrogen availabilities

Background and aims: Since actual production of wheat often leads to human Fe and Zn deficiency, a better understanding of the potential of arbuscular mycorrhizal fungal (AMF) inoculation for micro-nutrient uptake of durum wheat is needed. Methods: Effects of AMF field inoculation and N availability were evaluated on an old and a modern durum wheat variety Results: Following AMF inoculation, the modern variety showed a higher increase of the early root colonization respect to the old one, whereas at maturity root colonization was decreased by N fertilization. In the old variety grain N concentration was increased by inoculation when plants were not fertilized and at the 40–0-40 N, whereas in the modern variety inoculation did not change N concentration. By contrast, in AMF inoculated plots the modern variety showed a higher increase of Fe and Zn in grain compared to the old variety. Accordingly, at harvest, the modern variety showed an higher increase of a molecular operational taxonomic unit affiliated to Rhizophagus compared to the old variety. Conclusion: The inoculated isolate is a good durum wheat colonizer and the modern variety showed higher responsiveness to inoculation in terms of N, Fe and Zn grain concentration respect to the old one

Nature and Location of Cationic Lanthanum Species in High Alumina Containing Faujasite Type Zeolites

The nature, concentration, and location of cationic lanthanum species in faujasite-type zeolites (zeolite X, Y and ultrastabilized Y) have been studied in order to understand better their role in hydrocarbon activation. By combining detailed physicochemical characterization and DFT calculations, we demonstrated that lanthanum cations are predominantly stabilized within sodalite cages in the form of multinuclear OH-bridged lanthanum clusters or as monomeric La³⁺ at the SI sites. In high-silica faujasites (Si/Al = 4), monomeric [La(OH)]²⁺ and [La(OH)₂]⁺ species were only found in low concentrations at SII sites in the supercages, whereas the dominant part of La³⁺ is present as multinuclear OH-bridged cationic aggregates within the sodalite cages. Similarly, in the low-silica (Si/Al = 1.2) La–X zeolite, the SI′ sites were populated by hydroxylated La species in the form of OH-bridged bi- and trinuclear clusters. In this case, the substantial repulsion between the La³⁺ cations confined within the small sodalite cages induces the migration of La³⁺ cations into the supercage SII sites. The uniquely strong polarization of hydrocarbon molecules sorbed in La–X zeolites is caused solely by the interaction with the accessible isolated La³⁺ cations

'Candidatus Glomeribacter gigasporarum' gen. nov., sp nov., an endosymbiont of arbuscular mycorrhizal fungi

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Differential Expression of a Metallothionein Gene during the Presymbiotic versus the Symbiotic Phase of an Arbuscular Mycorrhizal Fungus

A full-length cDNA encoding a metallothionein (MT)-like polypeptide, designated GmarMT1, was identified in an expressed sequence tag collection from germinated spores of the arbuscular mycorrhizal fungus Gigaspora margarita (BEG34). The GmarMT1 gene is composed of two exons separated by an 81-bp intron. It codes for a 65-amino acid polypeptide comprising a plant type 1 MT-like N-terminal domain and a C-terminal domain that is most closely related to an as-yet-uncharacterized fungal MT. As revealed by heterologous complementation assays in yeast, GmarMT1 encodes a functional polypeptide capable of conferring increased tolerance against Cd and Cu. The GmarMT1 RNA is expressed in both presymbiotic spores and symbiotic mycelia, even in the absence of metal exposure, but is significantly less abundant in the latter stage. An opposite pattern was observed upon Cu exposure, which up-regulated GmarMT1 expression in symbiotic mycelia but not in germinated spores. Together, these data provide the first evidence, to our knowledge, for the occurrence in an arbuscular mycorrhizal fungus of a structurally novel MT that is modulated in a metal and life cycle stage-dependent manner and may afford protection against heavy metals (and other types of stress) to both partners of the endomycorrhizal symbiosis