Multicellular Spores Research Articles

Ulota langxianensis Qinghua Wang & Y.Jia (Orthotrichaceae), a new high-altitude moss species from China

ABSTRACT Introduction Worldwide, few species of Ulota are known from high-altitude regions (above 3000 m), and all these are in China or Papua New Guinea. In this article, we describe U. langxianensis Qinghua Wang & Y.Jia, a new species from the high-altitude region of Xizang (Tibet) in China. Methods The morphology of the new taxon was observed, measured, photographed and analysed using light microscopy. Phylogenetic inferences based on 78 concatenated plastid genes were made using maximum likelihood analyses. Key results and conclusions Ulota langxianensis is distinguished from other Ulota species by the long and smooth exostome teeth that are not united in pairs, large multicellular spores, weakly differentiated hyaline marginal cells at leaf base, and sparsely hairy calyptrae. Molecular phylogenetic analysis resolves U. langxianensis as sister to U. yunnanensis F.Lara, Caparrós & Garilleti. Gametophytically, U. langxianensis is similar to both U. yunnanensis and U. gigantospora F.Lara, Caparrós & Garilleti. Sporophytically it more closely resembles U. yakushimensis Z.Iwats. in having a single peristome and short exserted capsules, although all four species have multicellular spores. Ulota langxianensis is described in detail, along with information on its ecology and geographical distribution.

Composition and diversity of endolichenic microfungal communities from saxicolous lichens at Nahal Boker, the central Negev Desert, Israel

We studied the endolichenic fungal communities from saxicolous lichens occupying the cobbles at Nahal Boker, the central Negev Desert, Israel. Overall, 101 species belonging to 64 genera were isolated from 12 lichen species collected in three seasons from the south-facing slope (SFS) and north-facing slope (NFS) of the wadi. The endolichenic communities possessed a set of traits, which helped them to cope with harsh internal and external conditions. It included a prevalence of melanin-containing fungi with thick-walled and multicellular spores and a comparatively high contribution of thermotolerant species and species with meiospore-producing life cycle stage at the more microclimatically severe SFS. Species richness and isolate density of endolichenic communities was the highest in fruticose lichens with thick and wrinkled thalli, and the lowest in endolithic species possessing thin and smooth thalli. The communities from lichens formed a more diverse group than those from surrounding cobbles probably due to the influence of various species of lichens belonging to different growth forms.

Autophagy of the somatic stalk cells nurses the propagating spores of Dictyostelid social amoebas

Background: Autophagy (self-feeding) assists survival of starving cells by partial self-digestion, while dormancy as cysts, spores or seeds enables long-term survival. Starving Dictyostelium amoebas construct multicellular fruiting bodies with spores and stalk cells, with many Dictyostelia still able to encyst individually like their single-celled ancestors. While autophagy mostly occurs in the somatic stalk cells, autophagy gene knock-outs in Dictyostelium discoideum (D. discoideum) formed no spores and lacked cAMP induction of prespore gene expression. Methods: To investigate whether autophagy also prevents encystation, we knocked-out autophagy genes atg5 and atg7 in the dictyostelid Polysphondylium pallidum, which forms both spores and cysts. We measured spore and cyst differentiation and viability in the knock-out as well as stalk and spore gene expression and its regulation by cAMP. We tested a hypothesis that spores require materials derived from autophagy in stalk cells. Sporulation requires secreted cAMP acting on receptors and intracellular cAMP acting on PKA. We compared the morphology and viability of spores developed in fruiting bodies with spores induced from single cells by stimulation with cAMP and 8Br-cAMP, a membrane-permeant PKA agonist. Results: Loss of autophagy in P. pallidum reduced but did not prevent encystation. However, spore, but not stalk differentiation, and cAMP-induced prespore gene expression were lost. Spores induced in vitro by cAMP and 8Br-cAMP were smaller and rounder than spores formed multicellularly and while they were not lysed by detergent they did not germinate, unlike multicellular spores. Conclusions: The stringent requirement of sporulation on both multicellularity and autophagy, which occurs mostly in stalk cells, suggests that stalk cells nurse the spores through autophagy. This highlights autophagy as a major cause for somatic cell evolution in early multicellularity.

Callose in sporogenesis: Novel composition of the inner spore wall in hornworts.

Sporogenesis is a developmental process that defines embryophytes and involves callose, especially in the production of the highly protective and recalcitrant spore/pollen wall. Until now, hornworts, leptosporangiate ferns and homosporous lycophytes are the only major plant groups in which the involvement of callose in spore development is equivocal. Through aniline blue fluorescence and immunogold labeling in the transmission electron microscope, we provide indisputable evidence for the presence of callose in the spore wall of five hornwort genera, but not in the derived Dendroceros, an epiphyte that produces multicellular spores. We present evidence that callose appears in the developing spore wall and is retained throughout development as a wall constituent of the intine or inner spore wall, a novel location for this polysaccharide in embryophytes. In endosporic and multicellular spores/pollen of Dendroceros, the liverwort Pellia, and Arabidopsis, callose appears in the newly formed cell walls only following the first mitotic division. Further probing for other wall polymers in hornworts reveals the presence of cellulose (Calcofluor fluorescence) in the spore intine, aperture and around the equatorial girdle. Further immunogold labeling with monoclonal antibodies identifies pectin and hemicellulose in hornwort intines. The persistence of callose, a typically transient cell wall constituent, with cellulose, pectins and hemicellulose in the intine, supports specialized functions of callose in spores of hornworts that include reduced water loss when spores are dry and mechanical flexibility to withstand desiccation.

Phylogenetic and morphological infrageneric classification of the genus Dendroceros (Dendrocerotaceae; Anthocerotophyta), with the addition of two new subgenera

Dendroceros is one of the most diverse genera of hornworts, with 41 species and a widespread distribution. The genus is highly distinctive by its epiphytic habitat, gametophytes with perforated wings, multicellular spores due to endosporic germination, highly modified pyrenoid, and desiccation tolerance. The genus is monophyletic and, until now, was divided into two subgenera (subg. Apoceros and subg. Dendroceros). This classification has not been tested within a phylogenetic framework. Using published phylogenetic data from four molecular markers (rbcL, trnK including matK, rps4, and nad5) as well as morphological observations of over 80 specimens, we chose 38 morphological characters, which were mapped in the best maximum likelihood tree and optimized for reconstruction of ancestral character. We circumscribe the genus Dendroceros and propose 4 subgenera: subg. Apoceros (eight species), characterized for having schizogenous cavities in the midrib; subg. Dendroceros (14 species) with undulate-crispate gametophyte wings, and spore distal surface covered by aculeate papilla; subg. Nodulosus (five species) with rectangular cells in the capsule with nodular wall thickenings; and the monotypic subg. Cichoraceus with a single species that has granular spore micro-ornamentations, and a macro-ornamentation formed by pustulate papilla.

Cultured Microfungal Communities in Biological Soil Crusts and Bare Soils at the Tabernas Desert, Spain

We examined the variations in microfungal communities from different surface types (cyanobacterial crusts, lichen-dominated crusts, and noncrusted bare surface) at two different positions—north-oriented slope and sun-exposed plain in the Tabernas Desert, Spain. A total of 77 species from 46 genera was isolated using the soil dilution plate method. The studied mycobiota, similar to the majority of desert mycobiotas, was dominated by melanin-containing species. However, in the Tabernas crusts, unlike the studied crusts of the Negev Desert (Israel) and the Tengger Desert (China), melanized fungi with large multicellular spores were much less abundantly represented, while the thermotolerant group, Aspergillus spp., remarkably contributed to the communities’ structure. Density of microfungal isolates positively correlated with chlorophyll content indicating possible significant influence of organic matter content on fungal biomass. The variations in crust composition, biomass, and the position of habitats were accompanied by the variations in microfungal community structure, diversity level, and isolate densities, with the communities at the plain sun-exposed position being much less variable than the communities at the north-oriented position. The study shows that microclimatic and edaphic factors play an essential role in the development of crust and noncrust microfungal communities, and their structure can be a sensitive indicator of changing environmental conditions at a microscale.

Spatiotemporal variations in soil cultivable mycobiota at the Arava desert (Israel) along latitudinal and elevational gradients.

Regional, local, and seasonal distribution of soil culturable microfungi in the Arava Valley, Israel, was examined along altitudinal and latitudinal gradients. A total of 198 species from 86 genera were isolated using the soil dilution plate method. Melanin-containing species with large multi-cellular spores dominated the majority of microfungal communities, while species with picnidial fruit bodies mostly prevailed in the northern part of the Arava Valley located at 190 m below sea level. Aspergilli (mainly Aspergillus fumigatus) and teleomorphic ascomycetes comprised the basic part of thermotolerant mycobiota obtained at 37 °C. The soil at the northern part of the desert held the highest number of microfungal isolates and, at the same time, was characterized by significantly lower species richness. The open sun-exposed localities harbored a significantly higher number of species than the localities under shrub canopies. Isolate density displayed the opposite trend and was significantly lower in the open than in shrub localities. The mycobiota characteristics such as species composition, contribution of major groupings to mycobiota structure, diversity level, and isolate density showed significant correlations with measured edaphic parameters—organic matter content, water content, pH, and especially, with electrical conductivity. Among the environmental aspects, locality position along altitudinal and latitudinal gradients accompanied by locality type (open sun-exposed or under shrubs), strongly influenced the community's characteristics, thus demonstrating the effect of the unique altitudinal position of the northern part of the Arava Valley as well as the ability of microfungal communities to be sensitive to the microscale environmental variability.

Taxonomic notes on African Orthotrichaceae 2: Macrocoma – new synonymy and first report of multicellular spores

Type material of two poorly known species of Macromitrium, described from East Africa and Madagascar, was examined and both were found to belong to the genus Macrocoma. Macromitrium megalosporum Thér. & Naveau was found to be morphologically very close to Macrocoma abyssinica (Müll.Hal.) Vitt., with the only significant difference between these taxa being the large multicellular spores of M. megalosporum, which is also the first report of multicellular spores for the genus Macrocoma. This name is here transferred to Macrocoma as Macrocoma abyssinica var. megalospora (Thér. & Naveau) Wilbraham comb. nov. Macrocoma abyssinica var. megalospora is reported new for the Comoros, which is the first record for the species in the East African Islands. Macromitrium adelphinum Cardot in Grandidier was found to be conspecific with Macrocoma tenuis (Hook. & Grev.) Vitt. subsp. tenuis and an appropriate synonymy is proposed. Macrocoma tenuis. subsp. tenuis is also reported here new to the Comoros.

Three New Species and Nine New Records in the Genus Arthonia from South Korea

Arthonia coreana, Arthonia superpallens, and Arthonia zelkovae are new species from South Korea. All new species are in the Euarthonia tribe, based on the key characteristics of colorless hypothecium and multi-cellular spores. A. coreana has a dull brownish hypophloedal thallus without bleaching and rounded or curved big apothecia in comparison with those of Arthonia punctiformis. A. coreana consistently exhibits 4-septate ascospores, which is a distinctive characteristic that distinguishes it from other Arthonia species. A. superpallens has a white-greenish thallus, pale yellowish apothecia, and a trentepohlioid alga. However, A. superpallens has no distinct prothallus, adnate, and convex apothecia, no pycnidia, and is UV-, in contrast with related species in the Arthonia antillarum group. A. zelkovae has a white, epiphloedal thallus, brownish-black epruinose apothecia covered with a whitish bark layer, and smaller ascospores in comparison with those of A. punctiformis. A. zelkovae consists of a chlorococcoid alga, which differs from related Arthonia species such as A. punctiformis, Arthonia pinastri, and Arthonia glaucella. Although A. zelkovae is similar to Arthonia dispersa in its white-colored thallus, blackish apothecia, and the presence of a chlorococcoid photobiont, A. zelkovae differs from the latter in having larger-sized 3-septate ascospores. Arthonia cinnabarina f. marginata, A. glaucella, Arthonia ilicinella, Arthonia lapidicola, Arthonia leioplacella, Arthonia pertabescens, A. pinastri, Arthonia spadicea, and Arthonia stellaris are newly described in Korea. The diagnostic characteristics of these species are discussed and presented. An artificial key is provided to facilitate identification of Arthonia species from Northeast Asia.

Ulota larrainii (Orthotrichoideae, Orthotrichaceae, Bryophyta) a new species from Chile, with comments on the worldwide diversification of the genus

A new species of Ulota D. Mohr, U. larrainii, is described from the Aysén Region, southern Chile. The characters that discriminate the new moss are the prostrate habit, leaves not crisped, marginal cells of the leaf base differentiated in 1(2) rows, vaginula hairy, exostome of 8 pairs of orange, recurved teeth, endostome of 16 broad and hyaline segments, and large, multicellular spores. The new moss is illustrated and compared with similar taxa. In addition, the presence of multicellular spores in the genus Ulota is summarized and evaluated from an updated list of currently accepted species. Finally, the distribution, species richness and levels of endemism in the different regions where Ulota taxa occur are summarised and discussed with the help of a world map.

Cultivable Microfungal Communities Inhabiting Biological Soil Crusts in the Tengger Desert, China

Biological soil crusts are essential components of arid ecosystems. We examined the variations in microfungal communities inhabiting different biological crust types in the vicinity of the Shapotou Research Station in the Tengger Desert, China. A total of 134 species from 66 genera were isolated using the soil dilution plate method. The mycobiota of the crusts from the Tengger Desert, similar to that of the Negev Desert in Israel, was dominated by melanin-containing species with large multicellular spores. Abundance of these xeric species increased spatially with increasing xeric conditions from moss-dominated to cyanobacterial crusts. Density of microfungal isolates displayed the opposite trend and was positively correlated with chlorophyll content, indicating the possible significant influence of organic matter content and wetness duration on fungal biomass. Within a chronosequence of the localities of different periods after sand stabilization with revegetation, little variations were revealed in species composition and isolate density of the crust microfungal communities, while a tendency towards a decrease in the community diversity level with the crust age was noted Microfungal communities from stabilized localities differed from those of the natural localities in abundance of the dominant and some frequent species, and in the fluctuations of diversity characteristics between the cyanobacterial and moss-dominated crusts. The variations in mycobiotic parameters in the soil crusts of the Tengger Desert were apparently associated with the topographically induced variations in abiotic conditions, while the differences in microfungal community of soil crusts between the Tengger and Negev deserts, such as the significantly higher abundance of thermotolerant species in the crusts of the Tengger Deserts, were caused by the principal differences in their precipitation regimes, associated with different rainy seasons, winter and summer in the Negev and Tengger deserts, respectively.

Study of cellular development and intracellular lipid bodies accumulation in the thraustochytrid Aurantiochytrium sp. KRS101

Transmission electron, confocal microscopy and FACS in conjunction with two different lipophilic fluorescent dyes, BODIPY 505/515 and Nile Red were used to describe the cellular development and lipid bodies formation in Aurantiochytrium sp. KRS101. TEM results revealed that multi-cellular spores were appeared in sporangium during early-exponential phase, and spores were matured in mid-exponential phase followed by release of spores from sporangium in late-exponential phase. TEM and FACS analyses proved that lipid bodies appeared, developed and degenerated in mid-exponential, early- and late-stationary phases, respectively. The staining results in FACS indicate that BODIPY 505/515 is more effective for the vital staining of intracellular lipid bodies than Nile Red. FACS based single cell sorting also showed healthy growth for BODIPY 505/515 stained cells than Nile Red stained cells. In addition, a quantitative baseline was established either for cell growth and/or lipid accumulation based on cell count, fatty acid contents/composition, and sectional/confocal images of KRS101.

Two New Fissidens Species (Fissidentaceae) from Tropical Eastern Africa and Fissidens Bessouensis Corb., a Remarkable Species with Fimbriate Leaves and Multicellular Spores

Abstract Fissidens acrophilus Bruggeman-Nannenga, sp. nov. (subgenus Fissidens) from Kenya and Uganda and F. obscurifrons Bruggeman-Nannenga, sp. nov. (subgenus Fissidens?) from Tanzania are newly described and figured. F. obscurifrons is compared to the little known Madeiran F. nobreganus Luisier & P. de la Varde. A revision of F. bessouensis Corb. (subgenus Octodiceras) with description, diagnosis and figures and a discussion including adaptations to an aquatic habitat is presented. Multicellular spores and fimbriate leaf margins are reported in the Fissidentaceae for the first time. Rectification: F. angustelimbatus Mitt. is eliminated from the African flora.

New Ulota species with multicellular spores from southern South America

Abstract Two new Ulota species with multicellular spores, Ulota billbuckii and U. streptodon, are described from southern Chile. The new species are usually found growing together and sometimes forming mixed cushions or mats on different trees, with a preference for Nothofagus betuloides and N. antarctica. The new Ulotae are easily differentiated from each other as well as from other Ulota species with multicellular spores by a set of sporophytic traits including two very uncommon peristome configurations. In this paper, both species are described, and the differences between them as well as from other Ulotae with similar endosporic germination, and from superficially similar species, is discussed.

Orthotrichum scanicum Grönvall in Derbyshire: an epiphytic moss new to Britain

they are often reflexed (not completely recurved except in old capsules), i.e. remain patent or spreading, acquiring a star-shaped look. Moreover, O. mandonii possesses eight or 16 endostome segments, linear or long triangular and appendiculate, very different to the eight stout, obclavate segments of O. armatum. Finally, although some characters are also shared with O. armatum, any confusion with O. steeri is unlikely because it is a much larger moss, with distinct undulate leaves. This peculiar South American Orthotrichum also has larger spores (35– 45 mm after Lewinsky, 1987), but they are multicellular spores, a unique trait in the group and very uncommon within the Orthotrichaceae (Caparros et al., 2011). This work was funded by the Spanish Ministry of Science and Innovation (CGL2010-15693 and CGL2011-28857/BOS).

Parallel Evolution of Endospory within Hornworts: <I>Nothoceros renzagliensis</I> (Dendrocerotaceae), sp. nov.

The development of a gametophyte within the confines of the spore (i.e. endospory) is one essential innovation toward the evolution of seeds, but this feature also arose in seedless plants. In bryophytes, spores may begin to divide prior to dispersal and germination, but always develop into a free-living gametophyte. In hornworts, multicellular spores occur only in Dendroceros although they have also been observed in cultures of Phaeoceros carolinianus. Here, we describe a new species of Nothoceros, N. renzagliensis, from Pasto, Colombia, that differs from its congeners by its endosporic condition and Dendroceros-like spores. Gametophyte anatomy and sequence data from all cellular compartments place this species within the genus Nothoceros and as the sister taxon to all Neotropical Nothoceros. We re-evaluate the evolution of endospory in hornworts and we show two cases of parallel evolution of this trait across the hornwort phylogeny. Endospory seems to be a highly homoplastic feature across all bryophytes with several independent origins in mosses and liverworts.

Two new species of Ulota (Orthotrichaceae, Bryopsida) with multicellular spores, from the Hengduan Mountains, Southwestern China

Two new species, Ulota yunnanensis and Ulota gigantospora, are described from Yunnan and Sichuan Provinces, China. Both have multicellular spores, a relatively uncommon character in the genus. Differences between the species include growth form and habit, leaf areolation, capsule shape, peristome structure and ornamentation, operculum shape and colour, as well as vaginula and calyptra hairiness. These characters and those discriminating the new species from other ones with similar spore type are discussed and illustrated.

Soil crust microfungi along a southward rainfall gradient in desert ecosystems

We examined mycobiota structure, diversity level, and density of microfungal isolates in the biological soil crusts (BSC) and non-crusted soil of the northern and central Negev desert in 10 locations along a southward rainfall gradient. A total of 87 species from 49 genera were isolated. The mycobiota of BSC (80 species) was characterized by dominance of melanin-containing fungi, the remarkable contribution of sexual ascomycete species, and low abundance of the genera Penicillium and Aspergillus. Species richness and the contribution of dark-colored fungi with large, multicellular spores negatively and significantly correlated with rainfall. The comparison with mycobiota of the non-crusted soil showed that in BSC communities, the xeric “desert” component (melanics) was significantly more pronounced, and the mesic “forest” component ( Penicillium) was much less represented. In addition, the weak influence of rainfall on spatial variations of most observed mycobiotic characteristics indicated that microenvironmental factors (soil moisture, temperature, organic matter content) influenced the development of studied communities more essentially than macroenvironmental (climatic) factors.

A rapid method for assessing the viability of fungal spores1

The LIVE/DEAD® BacLight™ Bacterial Viability Kit (L-7007) manufactured by Molecular Probes, Inc. (Eugene, Oregon, U.S.A.), which provides a two-colour fluorescence assay of bacterial viability, was useful for determining the viability of the hyaline spores of Colletotrichum gloeosporioides f. sp. malvae, Leptosphaeria maculans, and Sclerotinia sclerotiorum and the thick-walled spores of Alternaria brassicae. Under blue light, viable spores fluoresced green and dead spores fluoresced red. Cells of multicellular spores fluoresced green or red according to their viability. In tests performed with S. sclerotiorum, there was no significant difference between viability as determined with the kit and in vitro germinability. With C. gloeosporioides, the proportion of spores that germinated in vitro was lower than the proportion of viable spores, indicating that not all viable spores could germinate.Key words: blackleg, black spot, two-colour fluorescence assay.

Airborne fungal spores trend over a highly polluted area of south-west Spain using Cour's trap

This investigation was aimed at studying the mycoflora present in Huelva (South West Spain), a highly polluted region. The study was carried out using the Cour trap and it is worth pointing out that the chemical treatment performed following the Cour methodology might destroy a certain percentage of spores. We analyzed the presence and biannual changes (10 April 1989 to 8 April 1991) of fungal spores of three genera, seventeen form genera, and four groups lacking taxonomic category, looking at their morphology: ascospores, basidiospores, and unidentified unicellular and multicellular spores. Special attention was given to agriculturally interesting groups. The results obtained were correlated with meteorological parameters (rainfall, minimum temperature and humidity).