Description and identification of Alnus acuminata ectomycorrhizae from Argentinean alder stands

The objective of this study was to describe the morphological and anatomical features of five unidentified ectomycorrhizal types of Alnus acuminata and to complement their identification based on ITS-rDNA sequence analysis. The combined approach of morphotyping and sequence analysis based on ITS sequence comparison with sequences contained in GenBank and the UNITE database let us assign three of the five field-collected ectomycorrhiza morphotypes to the tomentella-thelephora lineage that closely matched European and North American species. The sequencing results within Tomentella point toward alder specific clades within T. sublilacina, T. ellisii and T. stuposa sensu lato. The two other EcM morphotypes matched Lactarius omphaliiformis and a Russula sp. Better focused, concomitant fruit body surveys are needed for accurate identification of South American ectomycorrhizal fungi because of the evidence of cryptic speciation in both agaricoid and resupinate mycobionts.     

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.     

Ectomycorrhizas of Cortinarius helodes and Gyrodon monticola with Alnus acuminata from Argentina

Field ectomycorrhizas of Cortinarius helodes Moser, Matheny & Daniele (sp. nov) and Gyrodon monticola Sing. on Alnus acuminata Kunth (Andean alder, aliso del cerro) are described based on morphological and anatomical features. Ectomycorrhizal roots were sampled beneath fruitbodies of C. helodes and G. monticola from two homogeneous A. acuminata forest sites located in Tucumán and Catamarca Provinces in Argentina. C. helodes ectomycorrhizas showed a thick white to beige mantle exuding a milky juice when injured, were bluish toward the apex, and had hyphal strands in the mantle. G. monticola ectomycorrhizas showed some conspicuous features like highly differentiated rhizomorphs, inflated brown cells on the mantle surface, and hyaline and brown emanating hyphae with dolipores. Restriction fragment length polymorphism analysis of the nuclear rDNA internal transcribed spacer provided a distinctive profile for each of the collections of fruitbodies and the mycorrhizal morphotypes.     

Morphological-anatomical characterization and molecular identification of Tomentella stuposa ectomycorrhizae and related anatomotypes

Species in the genus Tomentella (Thelephoraceae) belong to the most frequent and widespread ectomycorrhizal (EM) fungi found in temperate and boreal forests. Although several unidentified tomentelloid morphotypes have been presented as common members of EM communities in coniferous and broad-leaved forests, few tomentelloid EM have been identified and described in detail. In this study, ten tomentelloid EM isolates collected from Populus alba, Quercus cerris and Picea abies stands in Hungary and Germany are characterized and documented by morphological-anatomical methods using light microscopy. The investigated ectomycorrhizae belong to the same brown-black tomentelloid morphotype but form two different anatomotype groups (At I and At II). Molecular taxonomical identification was accomplished using phylogenetic analysis (neighbor joining method) of 49 Tomentella nrDNA-ITS nucleotide sequences including the 10 new and 39 GenBank sequences. The EM isolates clustered into two adjoining clades identical with the two anatomotypes. At II clustered with Tomentella stuposa while At I could not be identified to species. Based on the morphological similarity and the low genetic difference it must be a closely related taxon. A comparison of the recently known tomentelloid EM to T. stuposa is presented. Ecological questions involving abundance and host relationships are discussed.     

Small genets of Lactarius xanthogalactus, Russula cremoricolor and Amanita francheti in late-stage ectomycorrhizal successions

We determined the size of genets of late-stage ectomycorrhizal fungi in field sites in coastal Northern California. Basidiocarps were collected, mapped and subjected to genetic fingerprinting using amplified fragment length polymorphisms (AFLPs). The minimum size estimates for the largest genets of Amanita francheti, Lactarius xanthogalactus and Russula cremoricolor were 1.5, 9.3 and 1.1 m2, respectively. The molecular markers also showed that R. cremoricolor is dimorphic, with red- and white-capped morphotypes of this species forming a continuous population. Our results suggest that spore propagation plays a much more important role in the life history of the Russulaceae in undisturbed forest settings than previously recognized. Fungi appearing late in the succession sequence and systems without obvious disturbance therefore do not necessarily colonize primarily by mycelium.     

中国特有植物喜树的雌性不育形态解剖学研究

为阐明雌性不育与喜树（Camptotheca acuminata Decne.）开花期花序大量掉落的关系,本文采用数码体视显微镜及石蜡切片技术,对各个发育时期的喜树的花进行解剖学观察。喜树花均为两性花,雄蕊发育正常,雌蕊柱头有三种不同形态,即上位、中位和下位;柱头上位的小花,花柱伸长正常,柱头三裂,外翻,子房膨大,胚珠饱满,胚囊发育正常;柱头中位的小花,雌蕊选择性败育,柱头和花柱伸长缓慢,柱头外翻异常,局部子房细胞液泡化,胚珠退化,胚囊发育异常;柱头下位的小花,花柱退化,柱头不露,珠被细胞发育异常,大孢子母细胞未能减数分裂,胚珠萎缩,子房外形瘦长,室内中空。喜树雌性器官的发育与其柱头在子房上的表现形态有着严格的对应关系,雌性不育发生于大孢子母细胞减数分裂前后,而且雌性不育是喜树花序掉落的内部原因之一。     

Morphological and molecular characterization of Frankia sp. isolates from nodules of Alnus nepalensis Don

Nodules collected from Alnus nepalensis growing in mixed forest stands at three different sites around Shillong, were crushed in various culture media to obtain isolates of Frankia. The isolates were found to have typical Frankia morphology as revealed by the scanning electron microscope. Seedlings inoculated with isolates or crushed nodules formed nitrogen fixing nodules. Frankia specific DNA probes amplified the DNA of the tested isolate AnpUS4. Partial nucleotide sequence of the 16S rRNA gene indicated that AnpUS4 was phylogenetically distinct from all other Frankia strains characterized so far.     

Morphological and molecular comparison of white truffle ectomycorrhizae

In the present study, white truffle ectomycorrhizae (EM) collected in deciduous forests (Populus, Quercus, and Fagus) from Hungary were characterized by morphological–anatomical and molecular methods. Our investigations suggest that the EM of white truffles (e.g., Tuber rapaeodorum, Tuber puberulum, Tuber rufum) are common and abundant members of the forest communities in the area. The ITS sequences of 14 EM specimens and 46 additional fruitbody sequences from the GenBank were clustered into four main groups in phylogenetic analyses. In the ITS-1 region, a characteristic indel pattern was found, which supports the clades. Although our analyses indicate definite genetic distance between the groups of the phylogenetic tree, these clades do not correspond to the traditional taxons identified by fruitbody characteristics. Comparison of the ectomycorrhizae shows that neither is mycorrhizal anatomy a good tool to separate the groups, because the characters (like the epidermoid or angular mantle structure, cell wall thickness, the sape and size of cystidia) are too variable and overlap between the clades. The interspecific similarity, observed both in ectomycorrhizal and fruitbody characters, strengthen the sensu lato morpho-species concept of this group. Our study, which combines comprehensive molecular and anatomical approach to characterize and identify ectomycorrhizae of white truffles from natural samples, stress out the need of the taxonomical revision of this group.     

Seasonal variations of symbiotic ultrastructure and relationships of two natural ectomycorrhizae of beech (Fagus sylvatica/Lactarius blennius var. viridis and Fagus sylvatica/Lactarius subdulcis)

This study concerned two perennial ectomycorrhizae of beech: Fagus sylvatica L./Lactarius blennius var. viridis and Fagus sylvatica L./Lactarius subdulcis, collected in a natural forest site. Nutritional exchanges existing between beech roots and fungi were evaluated over a seasonal cycle by studying the variations of ultrastructure, polyphosphate and nitrogenous granules and glycogen content (periodic acid thiocarbohydrazide silver test). The acid phosphatase activity, which is an indicator of the intensity of the physiological activity of symbiosis partners, was also revealed by transmission electron microscopy. The occurrence of the two ectomycorrhizae in the soil was not related to the climatic conditions. In winter, the number of polyphosphate and nitrogenous granules was high in the fungi, and glycogen was abundant in the cytoplasm of hyphae. In late winter, an intense acid phosphatase activity was revealed on plasmalemmas of live hyphae. It could indicate the beginning of fungal reserve mobilization, which progressively disappeared as spring progressed. In summer, glycogen was quasi non-existent and only few polyphosphate and nitrogenous granules were observed. At this period, the acid phosphatase activity was weak. Finally, in autumn and early winter, glycogen and granules were progressively restored in fungal structures. Relationships between changes of granules and glycogen content and the physiological states of each symbiont throughout the year are discussed.     

Ectomycorrhizae of Lactarius lignyotus on Norway spruce,characterized by anatomical and molecular tools

The ectomycorrhizae of Lactarius lignyotus on Norway spruce are comprehensively described by morphological and anatomical characteristics. Identification of ectomycorrhizae was performed by tracing mycelia to the fruitbodies and also by molecular tools, using polymerase chain reaction (PCR) amplification of the fungal DNA. The newly described ectomycorrhiza is compared to ectomycorrhiza of the related Lactarius picinus. The amplified DNA products of the two fungi and their ectomycorrhizae could be distinguished by characteristic fragments after digestion with Hinf1.Considered as part LV of the series Studies on ectomycorrhizae of the Institute for Systematic Botany, Munich; part LIV: Agerer et al. (1994)     

Comparative cytogenetics and molecular phylogeography in the group astyanax altiparanae--Astyanax aff. bimaculatus (Teleostei, Characidae)

The genus Astyanax comprises small characin fish of the neotropical region. The so-called 'yellow-tailed characins' compose one of the most widely distributed Astyanax groups. A. altiparanae and A. aff. bimaculatus, are evolutionarily closely related and commonly found in several Brazilian hydrographic basins. In the present work, chromosomal data of specimens of A. altiparanae and A. aff. bimaculatus from 4 hydrographic basins in the states of S?o Paulo (Upper Tietê, Paranapanema, Ribeira de Iguape) and Rio de Janeiro (Guapimirim) are shown. All the populations showed 50 chromosomes, with different karyotypic formula. Although only a single Ag-NOR bearing chromosome pair was observed, all populations possess multiple cistrons of 18S rDNA. FISH with the 5S rDNA probe showed single signals at the interstitial position of one metacentric chromosome pair. C-bands are distributed in the terminal and interstitial regions of several chromosomes. However, the As-51 satDNA are frugally located in a few chromosomes of fishes from Upper Tietê, Paranapanema and Guapimirim Rivers, being absent in individuals of A. aff. bimaculatus from Ribeira de Iguape River basin. Beside these 4 populations, molecular phylogeography studies were also performed in individuals from Middle and Lower Tietê River basin and from 2 additional collection sites in the Paranapanema and Ribeira de Iguape River basins. The phylogeographic analysis using 2 mtDNA regions (totalizing 1.314 bp of ND2 and ATPase6/8 genes) of 8 populations of the group of 'yellow-tailed characins' from 3 major hydrographic basins showed structuring of populations, suggesting a correlation between chromosomal (nuclear) and molecular (mitochondrial) data.     

Ectomycorrhizal and arbuscular mycorrhizal colonization of Alnus acuminata from Calilegua National Park (Argentina)

The objective of this study was to determine patterns of ectomycorrhizas (ECM) and arbuscular mycorrhizas (AM) colonization associated with Alnus acuminata (Andean alder), in relation to soil parameters (electrical conductivity, field H₂O holding capacity, pH, available P, organic matter, and total N) at two different seasons (autumn and spring). The study was conducted in natural forests of A. acuminata situated in Calilegua National Park (Jujuy, Argentina). Nine ECM morphotypes were found on A. acuminata roots. The ECM colonization was affected by seasonality and associated positively with field H₂O holding capacity, pH, and total N and negatively associated with organic matter. Two morphotypes (Russula alnijorullensis and Tomentella sp. 3) showed significant differences between seasons. Positive and negative correlations were found between five morphotypes (Alnirhiza silkacea, Lactarius omphaliformis, Tomentella sp. 1, Tomentella sp. 3, and Lactarius sp.) and soil parameters (total N, pH, and P). A significant negative correlation was found between field H₂O holding capacity and organic matter with AM colonization. Results of this study provide evidence that ECM and AM colonization of A. acuminata can be affected by some soil chemical edaphic parameters and indicate that some ECM morphotypes are sensitive to changes in seasonality and soil parameters.     

Positive relationship between wood size and basidiocarp production of polypore fungi in Alnus acuminata forest

Polypores play a major role in wood decomposition. Based on presence/absence of basidiocarps, it has been shown that richness of polypores in forests is strongly affected by the size of logs. However, no study has addressed the relationship between the log size and basidiocarp production. Here, we examined the relationship between log diameter and number of basidiocarps and volume of the fructification (as surrogate of biomass) of the polypore community in Andean Alder forests from Northwest Argentina. We found a positive relationship between log diameter and basidiocarp production in the whole community analysis (fructifications of all species). This pattern was also followed by dominant species (Bjerkandera adusta, Trametes cubensis and T. versicolor) analyzed individually. The relationship was generally higher for volume of fructification than for number of basidiocarps. Through these effects on basidiocarp production, higher log diameter could promote higher sexual spore production and dispersal hence a higher genetic variability and viable populations of wood-decay species.     

内蒙古地区5种棉革菌外生菌根形态描述和分子鉴定

本研究在内蒙古阿拉善和赤峰地区的青海云杉、白桦、油松、蒙古栎和沙地云杉这5个树种的林下采集菌根样品,分离得到5种棕色外生菌根形态型。从形态和解剖结构特征来看,这5种形态型都具有Tomentella外生菌根的形态特征。r DNA ITS区段系统发育分析表明,这5种形态型都是Tomentella真菌形成的外生菌根,其中4种形态型分别鉴定为:Tomentella ellisii、T.fuscocinerea、T.bryophila和T.stuposa。研究结果增加了对内蒙古自治区Tomentella多样性的认识。