Ornella Comandini

An overview of Cistus ectomycorrhizal fungi

The genus Cistus comprises a group of about 20 shrub species found in wide areas throughout the whole Mediterranean region to the Caucasus. Being one of the main constituents of the Mediterranean-type maquis, this plant genus is peculiar in that it has developed a range of specific adaptations to resist summer drought and frequent disturbance events, such as fire and grazing. In addition, it can form both ectomycorrhizas and arbuscular mycorrhizas. In this paper, we review the information available on the ectomycorrhizal fungi of Cistus across its entire geographic range, as gathered and critically sifted from both published literature sources and personal observations. Although the resulting data matrix was based primarily on accounts of sporocarp inventories in the field, existing knowledge on the features of Cistus natural and synthesized ectomycorrhizas was also included and discussed. In total, more than 200 fungal species belonging to 40 genera have been reported so far to be associated with Cistus. An analysis of the pattern of ectomycorrhizal diversity and host specificity revealed that members of the Cortinariaceae and Russulaceae make the most of both Cistus-aspecific and Cistus-specific mycobionts. Further studies are needed to expand our preliminary knowledge of the mycorrhizal ecology and biology of Cistus and its fungal associates, focusing on topics such as mycobiont diversity, host specificity, fungal succession, mycorrhizal influence on stress tolerance, and impact of disturbances, while comparing the findings with those from other ecosystems.

Effects of plant-derived naphthoquinones on the growth of Pleurotus sajor-caju and degradation of the compounds by fungal cultures

The growth of the white‐rot basidiomycete Pleurotus sajor‐caju in malt‐agar plates was inhibited by three naturally occurring, plant‐derived naphthoquinones: juglone, lawsone, and plumbagin. The latter two compounds exerted the most potent antifungal activity, and lawsone killed the mycelium at concentrations higher than 200 ppm. Plates containing juglone and lawsone presented large decolorized areas extending from area of fungal growth, suggesting an extracellular enzymatic degradation of these quinones. Screening of culture plates for extracellular enzymatic activities revealed the presence of both laccase and veratryl alcohol oxidase in most plates, the diffusion of both enzymes matching the decolorized area. In agitated cultures, the presence of juglone was found to stimulate the production of veratryl alcohol oxidase in a significant manner. This is the first time degradation of plant derived naphthoquinones by a white‐rot fungus is reported.

Lactarius ectomycorrhizae on Abies alba: morphological description, molecular characterization, and taxonomic remarks.

To date, the ectomycorrhizae formed by silver fir (Abies alba), an ecologically valuable and in- digenous tree species in many European mountain forests, have been poorly investigated. We character- ized the mycorrhizae formed by three Lactarius spe- cies (Lac. subsericatus, Lac. intermedius, Lac. salmon- icolor) on silver fir, on the basis of material originat- ing from central Italy. The identification of the fun- gal symbiont was achieved by means of morphoanatomical observations of mycorrhizae, and by comparison of ITS sequences obtained from my- corrhizae and sporocarps of putative fungal partners. Sequences also were obtained from specimens of the same species but from different geographic origin or from closely related Lactarius species. A maximum likelihood analysis of the data was performed. On the whole, the resultant tree is in good agreement with sporocarp and mycorrhiza morphology. RFLP pat- terns were calculated from sequence data. A discus- sion on the main morphoanatomical characters dis- tinguishing the Lactarius ectomycorrhizae reported in this study from those already described belonging to related species, is also included. The accuracy of different methods to identify mycorrhizae formed by closely related Lactarius species on silver fir, are dis-

Molecular and morphological characterization of Tuber magnatum mycorrhizas in a long-term survey.

Tuber magnatum Pico is an ectomycorrhizal fungus whose mycorrhizas can be barely distinguished morphologically from those of other related white truffles. Here we describe the use of specific primers based on the T. magnatum ITS sequence for screening mycorrhizas from a large number of growth chambers, greenhouse and nursery samples taken in a long-term survey. This molecular identification technique enabled a new morphological characterization to be set up for T. magnatum mycorrhizas.

Fungi in ectomycorrhizal associations of silver fir (Abies alba Miller) in Central Italy

Abstract Naturally occurring ectomycorrhizas of silver fir (Abies alba Miller) were studied in two stands, one natural and one artificial, situated in Central Italy. A total of 25 mycorrhizal types was classified, for eight of which the mycobiont was identified at the species level. Analysis of macroscopic and microscopic features and matching of field-collected carpophores with associated mycorrhizas led to the tentative identification of several other types encountered during this study, at least at the genus level. No significant differences were noticed between natural and artificial stands in the relative richness of mycorrhizal types found on A. alba, indicating the maturity of the artificial stand with regard to succession of ectomycorrhizal fungi. Confocal laser scanning microscopy was used for visualization of mycorrhizal structures formed by Lactarius spp., without the need for specific staining with a fluorochrome, thanks to latex autofluorescence. This technique allowed observation of several structures in greater detail than with conventional light microscopy.

Bioelectrical impedance vector analysis (BIVA) for the assessment of two-compartment body composition

This review is directed to define the efficacy of bioelectrical impedance vector analysis (BIVA) for assessing two-compartment body composition. A systematic literature review using MEDLINE database up to 12 February 2014 was performed. The list of papers citing the first description of BIVA, obtained from SCOPUS, and the reference lists of included studies were also searched. Selection criteria included studies comparing the results of BIVA with those of other techniques, and studies analyzing bioelectrical vectors of obese, athletic, cachectic and lean individuals. Thirty articles met the inclusion criteria. The ability of classic BIVA for assessing two-compartment body composition has been mainly evaluated by means of indirect techniques, such as anthropometry and bioelectrical impedance analysis (BIA). Classic BIVA showed a high agreement with body mass index, that can be interpreted in relation to the greater body mass of obese and athletic individuals, whereas the comparison with BIA showed less consistent results, especially in diseased individuals. When a reference method was used, classic BIVA failed to accurately recognize FM% variations, whereas specific BIVA furnished good results. Specific BIVA is a promising alternative to classic BIVA for assessing two-compartment body composition, with potential application in nutritional, sport and geriatric medicine.

Characterization of Lactarius tesquorum ectomycorrhizae on Cistus sp. and molecular phylogeny of related European Lactarius taxa

Lactarius is one of the larger genera of ectomycorrhizal Basidiomycota, with about 400 species recognized worldwide. The ectomycorrhizae formed by Lactarius tesquorum on Cistus sp., one of the most common and ecologically relevant shrubs in the semi-arid regions in the Mediterranean basin, are described here in terms of morphological, anatomical and molecular features. An ITS rDNA sequence-based phylogenetic analysis was performed on the related European Lactarius taxa (L. mairei, L. pubescens, L. scoticus, L. spinosulus, L. torminosulus and L. torminosus) currently classified together with L. tesquorum in the subgenus Piperites section Piperites. Piperites s.s. could be divided into two main clusters; L. mairei and especially L. spinosulus were related less closely to the other taxa. This study is part of a broader effort to extend our knowledge of the distribution, phylogeny and ectomycorrhizal biology of Lactarius species in selected ecosystems.

Cytokinin oxidase strikes again

Research into the enzymes involved in several aspects of cytokinin metabolism (including storage and catabolic pathways) is undergoing an unprecedented period of success. We recently reported1xCytokinin oxidase: new insight into enzyme properties. Rinaldi, A.C. and Comandini, O. Trends Plant Sci. 1999; 4: 127–128Abstract | Full Text | Full Text PDFSee all References1 on new findings concerning the biochemical and molecular properties of cytokinin oxidase (CKO), a poorly characterized, but crucial enzyme, which irreversibly inactivates cytokinins. Although CKO has been classified as a copper-containing amine oxidase1xCytokinin oxidase: new insight into enzyme properties. Rinaldi, A.C. and Comandini, O. Trends Plant Sci. 1999; 4: 127–128Abstract | Full Text | Full Text PDFSee all References1, clear evidence is now emerging that argues against this classification2xCytokinins as inhibitors of plant amine oxidase. Galuszka, P. et al. J. Enzyme Inhib. 1998; 13: 457–463Crossref | PubMedSee all References, 3xIsolation of a gene encoding a glycosylated cytokinin oxidase from maize. Morris, R.O. et al. Biochem. Biophys. Res. Commun. 1999; 255: 328–333Crossref | PubMed | Scopus (123)See all References, 4xCytokinin oxidase from Zea mays: purification, cDNA cloning and expression in moss protoplasts. Houba-Herin, N. et al. Plant J. 1999; 17: 615–626Crossref | PubMed | Scopus (125)See all References. In particular, as previously described1xCytokinin oxidase: new insight into enzyme properties. Rinaldi, A.C. and Comandini, O. Trends Plant Sci. 1999; 4: 127–128Abstract | Full Text | Full Text PDFSee all References1, there is evidence that CKO from wheat is an FAD-containing flavoprotein (P. Galuszka et al., unpublished), and recent advances have further extended this finding3xIsolation of a gene encoding a glycosylated cytokinin oxidase from maize. Morris, R.O. et al. Biochem. Biophys. Res. Commun. 1999; 255: 328–333Crossref | PubMed | Scopus (123)See all References, 4xCytokinin oxidase from Zea mays: purification, cDNA cloning and expression in moss protoplasts. Houba-Herin, N. et al. Plant J. 1999; 17: 615–626Crossref | PubMed | Scopus (125)See all References.The predominant CKO from immature maize kernels has now been purified and its structural gene (ckx1) has been isolated and characterized3xIsolation of a gene encoding a glycosylated cytokinin oxidase from maize. Morris, R.O. et al. Biochem. Biophys. Res. Commun. 1999; 255: 328–333Crossref | PubMed | Scopus (123)See all References3. The gene encodes a glycosylated protein of ∼57 kDa that possesses an 18 amino acid signal peptide and a consensus FAD-binding sequence3xIsolation of a gene encoding a glycosylated cytokinin oxidase from maize. Morris, R.O. et al. Biochem. Biophys. Res. Commun. 1999; 255: 328–333Crossref | PubMed | Scopus (123)See all References3. By expressing ckx1 in Pichia it was possible to obtain an active glycosylated-CKO that was secreted into the culture medium. The absorption spectrum of the recombinant enzyme, which shows substrate reactivity similar to that reported for the native enzyme, indicated the presence of substrate-reducible FAD, whereas no copper ions were detected by atomic absorption analysis3xIsolation of a gene encoding a glycosylated cytokinin oxidase from maize. Morris, R.O. et al. Biochem. Biophys. Res. Commun. 1999; 255: 328–333Crossref | PubMed | Scopus (123)See all References3. The search for homology to other genes revealed that ckx1 has sequence homology (>40% identity in the derived amino acid sequences) with a putative oxidoreductase from Arabidopsis thaliana, and, to a lesser extent, with the fas5 gene from Rhodococcus fascians3xIsolation of a gene encoding a glycosylated cytokinin oxidase from maize. Morris, R.O. et al. Biochem. Biophys. Res. Commun. 1999; 255: 328–333Crossref | PubMed | Scopus (123)See all References3.About the same time, the group led by Michel Laloue4xCytokinin oxidase from Zea mays: purification, cDNA cloning and expression in moss protoplasts. Houba-Herin, N. et al. Plant J. 1999; 17: 615–626Crossref | PubMed | Scopus (125)See all References4 reported similar results on maize CKO to those of Morris and colleagues3xIsolation of a gene encoding a glycosylated cytokinin oxidase from maize. Morris, R.O. et al. Biochem. Biophys. Res. Commun. 1999; 255: 328–333Crossref | PubMed | Scopus (123)See all References3. In this study, photolabelling of maize CKO with a tritiated azido-derivative of N-(2-chloro-4-pyridyl)-N′-phenylurea (a potent cytokinin agonist and CKO inhibitor) facilitated purification of the enzyme by preparative 2D-gel electrophoresis. Subsequently, the CKO cDNA was isolated, cloned and expressed in moss (Physcomitrella patens) protoplasts to generate a catalytically active maize CKO (Ref. 4xCytokinin oxidase from Zea mays: purification, cDNA cloning and expression in moss protoplasts. Houba-Herin, N. et al. Plant J. 1999; 17: 615–626Crossref | PubMed | Scopus (125)See all ReferencesRef. 4). The deduced CKO amino acid sequence shows sequence homology with an FAD-binding domain common to several oxidases. Moreover, a GHS motif was found in the maize CKO sequence, suggesting that the enzyme might covalently bind to FAD through a histidine residue4xCytokinin oxidase from Zea mays: purification, cDNA cloning and expression in moss protoplasts. Houba-Herin, N. et al. Plant J. 1999; 17: 615–626Crossref | PubMed | Scopus (125)See all References4.In conclusion, maize CKO has now been cloned and expressed in two independent laboratories using different approaches. This has confirmed that the enzyme is an FAD-dependent oxidase. Several pieces of evidence confirm, therefore, that the previous classification of CKO among copper amine oxidases can be dropped, and that CKO belongs instead to the large family of FAD amine oxidases.The progress made on CKO comes at a time of significant advances in research on other enzymes involved in the control of the cytokinin cell cycle. The genes encoding two enzymes, O-glucosyltransferase5xIsolation of a cytokinin gene, ZOG1, encoding zeatin O-glucosyltransferase from Phaseolus lunatus. Martin, R.C., Mok, M.C., and Mok, D.W.S. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 284–289Crossref | PubMed | Scopus (85)See all References5 and O-xylosyltransferase6xA gene encoding the cytokinin enzyme zeatin O-xylosyltransferase of Phaseolus vulgaris. Martin, R.C., Mok, M.C., and Mok, D.W.S. Plant Physiol. 1999; 120: 553–558Crossref | PubMedSee all References6, from Phaseolus lunatus and P. vulgaris, respectively, which catalyse the formation of O-glycosyl derivatives of zeatin (the most active and ubiquitous of the naturally occurring cytokinins) have recently been isolated. The two genes exhibit 93% identity at the nucleotide level and the deduced amino acid sequence has 90% similarity5xIsolation of a cytokinin gene, ZOG1, encoding zeatin O-glucosyltransferase from Phaseolus lunatus. Martin, R.C., Mok, M.C., and Mok, D.W.S. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 284–289Crossref | PubMed | Scopus (85)See all References, 6xA gene encoding the cytokinin enzyme zeatin O-xylosyltransferase of Phaseolus vulgaris. Martin, R.C., Mok, M.C., and Mok, D.W.S. Plant Physiol. 1999; 120: 553–558Crossref | PubMedSee all References. Because glycosyl conjugates of zeatin are found in many plant tissues and are assumed to be important for transport and storage, and protection against degradative enzymes (such as CKO), the cloning of these genes will benefit further studies on the regulation of cytokinin metabolism.

Molecular and morpho-anatomical description of mycorrhizas of Lactarius rimosellus on Quercus sp., with ethnomycological notes on Lactarius in Guatemala

Guatemala is one of the richest biodiversity hotspots worldwide, bursting a wild array of ecosystems that range from pine and mixed forests in the highlands to tropical rain forests in the extensive El Petén area, bordering Belize and Mexico. Despite this biological wealth, however, current knowledge on the Guatemalan mycobiota is particularly scant, in part because of the prolonged civil war that has prevented exploration of many ecological niches. In the present paper, we report on the occurrence of Lactarius rimosellus Peck—a rarely discussed species—in oak-pine mixed forests in the Guatemalan highlands and describe the relevant ectomycorrhizae formed with Quercus sp. by means of molecular and morpho-anatomical tools. On the phylogenetic trees constructed on the basis of the partial LSU sequence, sporocarp- and ectomycorrhizae-derived sequences formed a common, statistically supported clade. The structural features of the ectomycorrhizae of L. rimosellus were generally found to match those described on various hosts for other Lactarius species belonging to the subgenus Russularia, where L. rimosellus has been traditionally assigned. These mycorrhizae are characterized by a pseudoparenchymatous outer mantle layer, with epidermoid or angular hyphal cells, and a plectenchymatous inner mantle layer; lactifers are embedded either in the middle and/or inner mantle layer. In the framework of a more general, ongoing study of the ethnomycology of the Maya populations in the Guatemalan highlands, we also report on the traditional knowledge about Lactarius mushrooms and their uses among native people.

The nutrition transition in the Venezuelan Amazonia: increased overweight and obesity with transculturation

Amerindians have a particularly high propensity to overweight and obesity as they change lifestyle and experience a nutrition transition. The aim of this study was to evaluate the effects of transculturation on nutritional status in three Amazonian Amerindian villages.