Enhancing our understanding of anatomical diversity in Tomentella ectomycorrhizas: characterization of six new morphotypes.

Ectomycorrhizas (ECM) formed by Tomentella species (Thelephorales, Basidiomycota) were collected in beech forests of Hungary and studied using anatomical and molecular phylogenetic methods. The mycobionts were identified by analysing the sequences of nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) regions together with sequences obtained from public databases. At the sampling plots, we found the occurrence of 11 Tomentella morphotypes. Among these, six morphotypes (four identified, Tomentella atroarenicolor, Tomentella bryophila, Tomentella lapida, Tomentella subclavigera, and two unidentified) were morpho-anatomically characterized for the first time. Although the six morphotypes differed anatomically from each other and from Tomentella ectomycorrhizas described previously, they shared anatomical features common to tomentelloid ectomycorrhizas fungi. These results expand our understanding of the diversity of this widely distributed ectomycorrhizal genus.

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.

Characterization of beech ectomycorrhizae formed by species of the Pachyphloeus-Amylascus lineage.

The hypogeous genus Pachyphloeus forms a common phylogenetic lineage with the epigeous Scabropezia and the hypogeous Amylascus, within the Pezizaceae (Ascomycota). Though the ectomycorrhiza- (EM) forming ability of this group was proposed previously, no detailed description has been published up to now, except for the characterization of EM related to P. virecens. During our several-year-long survey on the EM community of a beech forest reserve in Hungary, we found ten EM specimens belonging to the Pachyphloeus-Amylascus lineage. All of them share common morphological and anatomical characters. The densely ramifying whitish-yellow to light-brown mycorrhizal systems are pyramidal with short, stout ends. The EM surface is densely wooly with white or brown, curly hyphae. All mantle layers are pseudoparenchymatous angular, covered by a thick-walled hyphal network. Frequent emanating hyphae are densely septate without clamps. The EM can be sorted into three different morphotypes (Mt) according to their color, specific morphometric traits (cell-wall thickness, diameter of emanating hyphae, septal distance), and certain anatomical characters (structure of the surface net). Molecular identification was accomplished by the phylogenetic analysis of the ITS and LSU regions of the nrDNA, what proved that the sequences clustered into three clades corresponding to the three Mt. With the aid of fruitbody-derived sequences, obtained from GenBank, one of the Mt can be identified as Pachyphloeus melanoxanthus and another one as Pachyphloeus citrinus. The third Mt, together with another unidentified EM sequence of the GenBank, forms a distinct branch, which is a sister group to the Pachyphloeus-Scabropezia-Amylascus lineage. In addition to presenting the first detailed anatomical and molecular comparison of the EM related to P. melanoxanthus and P. citrinus, we call the attention to the need for further microscopical investigations amended by molecular taxonomical analyses.

Identification, Structural and Functional Characterization of Dormancy Regulator Genes in Apricot (Prunus armeniaca L.).

In the present study, we identified and characterized the apricot (Prunus armeniaca L.) homologs of three dormancy-related genes, namely the ParCBF1 (C-repeat binding factor), ParDAM5 (dormancy-associated MADS-BOX) and ParDAM6 genes. All highly conserved structural motifs and the 3D model of the DNA-binding domain indicate an unimpaired DNA-binding ability of ParCBF1. A phylogenetic analysis showed that ParCBF1 was most likely homologous to Prunus mume and Prunus dulcis CBF1. ParDAM5 also contained all characteristic domains of the type II (MIKCC) subfamily of MADS-box transcription factors. The homology modeling of protein domains and a phylogenetic analysis of ParDAM5 suggest its functional integrity. The amino acid positions or small motifs that are diagnostic characteristics of DAM5 and DAM6 were determined. For ParDAM6, only a small part of the cDNA was sequenced, which was sufficient for the quantification of gene expression. The expression of ParCBF1 showed close association with decreasing ambient temperatures in autumn and winter. The expression levels of ParDAM5 and ParDAM6 changed according to CBF1 expression rates and the fulfillment of cultivar chilling requirements (CR). The concomitant decrease of gene expression with endodormancy release is consistent with a role of ParDAM5 and ParDAM6 genes in dormancy induction and maintenance. Cultivars with higher CR and delayed flowering time showed higher expression levels of ParDAM5 and ParDAM6 toward the end of endodormancy. Differences in the timing of anther developmental stages between early- and late-flowering cultivars and two dormant seasons confirmed the genetically and environmentally controlled mechanisms of dormancy release in apricot generative buds. These results support that the newly identified apricot gene homologs have a crucial role in dormancy-associated physiological mechanisms.

Morphological-anatomical characterization and identification of Tomentella ectomycorrhizas.

Over the last two decades, much information has been gathered on the ectomycorrhizal fungus community composition of plant associations of boreal, temperate, and tropical regions. Worldwide, Tomentella ectomycorrhizas (ECM) are often common and dominant in the mycorrhizosphere of coniferous and deciduous forests. They are present under different environmental conditions and associate with diverse plant hosts. Tomentella sporocarps, however, are rarely found aboveground, so Tomentella species are often missing from fungus community studies based on fruit-body presence. Tomentella is a resupinate genus of Thelephoraceae (Basidiomycota) forming black-brown, brown, yellow, or ochre ECM on the roots of gymnosperm and angiosperm trees, distinguished by typical morphological-anatomical characteristics (clamped hyphae, angular mantle, surface network, special rhizomorphs and cystidia). In this paper, we review the taxonomic position and morphological-anatomical characteristics of Tomentella ECM. A short summary of the microscopic features used for distinguishing tomentelloids during morphotyping and identification is presented in order to support molecular and ecological studies of ectomycorrhizal fungus communities.

Morphological and molecular characterization of Humaria and Genea ectomycorrhizae from Hungarian deciduous forests.

The ectomycorrhizae (EM) of Humaria and Genea, two closely related genera of the Pyronemataceae (Ascomycetes), were regularly found in different deciduous forests of Hungary. In the present paper, the morphology and anatomy of these EM are described in detail, including morphometric analyses. Identification of the EM was carried out by molecular taxonomic analyses of the nrDNA ITS sequences obtained from mycorrhizae, herbarium ascomata, and public databases. The anatomy of the EM, examined during this work, was almost identical. They possessed angular outer and epidermoid inner mantle layers and warted, thick-walled emanating hyphae. Ten of our EM sequences grouped into the clade of Humaria hemisphaerica sequences and one into the genus Genea. Both molecular taxonomic analysis and morphometry differentiated three sub-groups within the clade of Humaria, and these methods also clearly separated the EM of Genea from those of Humaria. We may suppose that the previous morphological-anatomical descriptions, lacking molecular taxonomic identification, do not concern the denominated taxa. As a consequence, we stress the importance of revaluating the literature data, based on morphotyping of Humaria and Genea EM, to prevent misidentification in future studies. The presented work demonstrates that combining molecular and morphological analysis is essential for the unambiguous identification of the EM formed by problematic taxa.

Morphological and molecular diversity and abundance of tomentelloid ectomycorrhizae in broad-leaved forests of the Hungarian Plain.

The most common representatives of tomentelloid ectomycorrhizae (EM) collected in broad-leaved forests (Populus and Quercus) of the Hungarian Plain during a 4-year project are demonstrated. Eighteen specimens of nine tomentelloid EM morphotypes were investigated. Five of these, introduced here for the first time, were characterized by microscopical-morphological and anatomical methods. Molecular identification was carried out using sequence analysis of the nrDNA ITS region. Altogether, 54 ITS sequences (6 previously published and 12 new sequences from our mycorrhizae and 36 from GenBank derived from fruitbodies) were compared by phylogenetic analyses using neighbor-joining, maximum parsimony and maximum likelihood methods. Identification to species level was successful in the case of six EM morphotypes (Tomentella galzinii, T. subtestacea, T. sublilacina, T. pilosa, T. ferruginea and T. stuposa), and the possible taxonomic position of the remaining three was approached. These results are supported by morphology, as compared with literature data. Relative abundance of the EM morphotypes within the soil samples was estimated. Our results confirm that tomentelloid EM are constant, diverse and abundant members of the EM communities in temperate-continental broad-leaved forests.