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To adapt to a terrestrial habitat, the ancestors of land plants must have made several morphological and physiological modifications, such as a meristem allowing for three-dimensional growth, rhizoids for water and nutrient uptake, air pore complexes or stomata that permit air exchange, and a defense system to cope with oxidative stress that occurs frequently in a terrestrial habitat. To understand how the meristem was determined during land plant evolution, we characterized the function of the closest PLETHORA homolog in the liverwort Marchantia polymorpha , which we named Mp PLT. Through a transgenic approach, we showed that Mp PLT is expressed not only in the stem cells at the apical notch but also in the proliferation zone of the meristem, as well as in cells that form the air-pore complex and rhizoids. Using the CRISPR method we then created mutants for Mp PLT and found that the mutants are not only defective in meristem maintenance but also compromised in air-pore complex and rhizoid development. Strikingly, at later developmental stages, numerous gemma-like structures were formed in Mp plt mutants, suggesting developmental arrest. Further experiments indicated that Mp PLT promotes plant growth by regulating Mp WOX , which shared a similar expression pattern to Mp PLT , and genes involved in auxin and cytokinin signaling pathways. Through transcriptome analyses, we found that Mp PLT also has a role in redox homeostasis and that this role is essential for plant growth. Taken together, these results suggest that Mp PLT has a crucial role in liverwort growth and development and hence may have played a crucial role in early land plant evolution. [ABSTRACT FROM AUTHOR]

Simple Summary: This paper reports on three new species and a new record of the lichen genus Peltula Nyl., highlighting research progress on lichen diversity in Helan Mountain. In this study, species were identified through a combination of morpho-anatomy, molecular systematics, and chemical substance detection. The results of the study enrich the data of Peltula and the study of lichens in Helan Mountain. In this study, a systematic taxonomic analysis was carried out on the lichen genus Peltula, collected from Helan Mountain in China; three new species (Peltula helanense, P. overlappine, and P. reticulata) and a new record (P. crispatula (Nyl.) Egea) for China were identified. Four species were identified by morph-anatomical, chemical, and phylogenetic analyses by combining two gene loci (ITS and LSU). Peltula helanense is with tiny individual thalli up to 1mm, attached by creamy-white cylindrical rhizoids and apothecia filling the whole squamule. Peltula overlappine is characterized by thallus squamulose forming rosette-shaped patches and squamules with distinctive thickened margins. Peltula reticulata is characterized by brownish brown thallus and squamules with densely reticulate upper surface. P. crispatula is characterized by irregular squamules attached to a tuft of hyphae. The four species are described in detail, compared, and discussed with similar species, and images of morpho-anatomical structures of the four species are also provided. Moreover, a key to the species of Peltula from Helan Mountain is provided. The results enrich the data of the genus Peltula and also indicate that the rich diversity of lichen species in Helan Mountain is worthy of in-depth study. [ABSTRACT FROM AUTHOR]

Octospora pulchrispora Sochorová et Eckstein is described as a new species based on finds from the Czech Republic. It features a remarkable ascospore ornamentation formed by low, branching, cyanophilous ridges. It parasitises the acrocarpous moss Cynodontium polycarpon (Rhabdoweisiaceae) and induces galls on the rhizoids. In the phylogenetic analysis based on the LSU, SSU and EF1) loci, O. pulchrispora formed a highly supported clade with Octospora gyalectoides agg., O. leucoloma, O. gemmicola, O. axillaris, O. excipulata, O. bridei and two undescribed Octospora species. [ABSTRACT FROM AUTHOR]

Bacteria and marine macroalgae form close associations, while various bacteria affect the morphogenesis and growth of macroalgae. Hyphomonas strains exhibit normal morphogenetic activity in protoplasts of the red alga Pyropia yezoensis (nori). However, the effects of the bacteria on the growth of Pyropia from protoplast cells to regenerated thalli remain unknown. Here, we assessed the growth of P. yezoensis and Pyropia tenera using combined cultures of three Hyphomonas strains (LNM10-16, SCM-2, and LNM-9) and three algal media (artificial seawater with vitamins, artificial seawater, and natural seawater) over 7 weeks. Third week after culture, the three Hyphomonas strains showed almost similar levels of normal growth activity for both Pyropia species. However, at 7 weeks, significant differences were observed among the three Hyphomonas strains in terms of length, length-to-width ratio, and normal morphology of Pyropia thalli. LNM10-16 significantly promoted the thalli length and length-to-width ratios of both Pyropia species in artificial seawater without vitamins and natural seawater, compared with the other two Hyphomonas strains. P. yezoensis cultured in artificial seawater with vitamins showed a much higher demand for LNM10-16 in development of the thalli length than P. tenera. These results may be explained by differences in the growth activities of Hyphomonas strains and the nutrient requirements of Pyropia species. Furthermore, the bacteria were more specifically attached to the rhizoid surfaces of both species. This study is the first to reveal that Hyphomonas strains affect the growth of Pyropia species by attaching to their rhizoids. [ABSTRACT FROM AUTHOR]

SUMMARY: A combination of streamlined genetics, experimental tractability and relative morphological simplicity compared to vascular plants makes the liverwort Marchantia polymorpha an ideal model system for studying many aspects of plant biology. Here we describe a transformation vector combining a constitutive fluorescent membrane marker with a nuclear marker that is regulated by nearby enhancer elements and use this to produce a library of enhancer trap lines for Marchantia. Screening gemmae from these lines allowed the identification and characterization of novel marker lines, including markers for rhizoids and oil cells. The library allowed the identification of a margin tissue running around the thallus edge, highlighted during thallus development. The expression of this marker is correlated with auxin levels. We generated multiple markers for the meristematic apical notch region, which have different spatial expression patterns, reappear at different times during meristem regeneration following apical notch excision and have varying responses to auxin supplementation or inhibition. This reveals that there are proximodistal substructures within the apical notch that could not be observed otherwise. We employed our markers to study Marchantia sporeling development, observing meristem emergence as defining the protonema‐to‐prothallus stage transition, and subsequent production of margin tissue during the prothallus stage. Exogenous auxin treatment stalls meristem emergence at the protonema stage but does not inhibit cell division, resulting in callus‐like sporelings with many rhizoids, whereas pharmacologically inhibiting auxin synthesis and transport does not prevent meristem emergence. This enhancer trap system presents a useful resource for the community and will contribute to future Marchantia research. [ABSTRACT FROM AUTHOR]

Endoplura gyeokpoensis sp. nov. and E. limpeticola sp. nov. from Korea are described based on molecular and morphological analyses. The crustose brown algal genus Endoplura previously comprised three species: E. aurea, E. jejuensis and E. koreana. Our phylogenetic analyses inferred from rbcL and concatenated rbcL and COI-5P data revealed that E. gyeokpoensis sp. nov. and E. limpeticola sp. nov. are placed in the Endoplura clade with robust bootstrap support and Bayesian posterior probabilities. Endoplura gyeokpoensis is characterized by small crustose thalli, thallus outline with a lighter margin, and 2–4 plurangia terminated by 2–3 sterile cells. Endoplura limpeticola is distinguished by epizoic crustose thalli on limpets, thick thalli up to 751 μm, thallus outline with a darker margin, multicellular rhizoids, and two plurangia terminated by 2–3 sterile cells. Our study shows that the two new Endoplura species are molecularly and morphologically distinguished from each other as well as from the congeners. [ABSTRACT FROM AUTHOR]

Chytridiomycota (zoosporic true fungi) have a consistent presence in soils and have been frequently identified within many diverse terrestrial environments. However, Chytridiomycota and other early-diverging fungi have low representation in whole-genome sequencing databases compared to Dikarya. New molecular techniques have provided insights into the diversity and abundance of chytrids in soils and the changes in their populations both spatially and temporally. Chytrids complete their life cycle within rapidly changing soil environments where they may be more common within micropores due to protection from predation, desiccation, and extreme temperatures. Reproductive and morphological changes occur in response to environmental changes including pH, fluctuating nutrient concentrations, and metals at levels above toxic thresholds. Rhizoids share some features of hyphae, including the spatial regulation of branching and the ability to attach, adapt to, and proliferate in different substrates, albeit on a microscale. Soil chytrids provide a pool of novel enzymes and proteins which enable a range of lifestyles as saprotrophs or parasites, but also can be utilised as alternative tools with some biotechnological applications. Thus, 3D live-cell imaging and micromodels such as MicroCT may provide insight into zoospore functions and rhizoid plasticity, respectively, in response to various conditions. A combination of classical techniques of soil chytrid baiting with simultaneous molecular and ecological data will provide insights into temporal population changes in response to environmental change. The authors emphasise the need to review and improve DNA-based methodologies for identifying and quantifying chytrids within the soil microbiome to expand our knowledge of their taxonomy, abundance, diversity, and functionality within soil environments. [ABSTRACT FROM AUTHOR]

Four species of Erythrotrichia (E. biseriata, E. reflexa, E. tetraseriata, E. carnea) have been reported in Korea, but phylogenetic studies have not been conducted on them. We analyzed two newly collected Erythrotrichia isolates using rbcL DNA sequences and determined their species status using four DNA-based species delimitation methods. One isolate (KNU-1) grouped with E. carnea in three methods: Assemble Species by Automatic Partitioning, both single-threshold and multiple-threshold general mixed yule coalescent, but grouped as a distinct species in the statistical parsimony network analysis. A second isolate (KNU-2) was considered a distinct species in all the above species-delimitation methods. We propose the name, Erythrotrichia johnawestii sp. nov., for this new species. The new species was different from E. carnea in lacking a thick outer cell wall layer and with a smaller cell size. Mature monosporangia produced raised openings that released monospores. Cell walls were not detected in newly released monospores but began to appear when the spore attached to the substratum and produced rhizoids. Sexual reproduction was not observed during the four-year culture period. [ABSTRACT FROM AUTHOR]

To uncover the nature of various kinds of stolons of Utricularia subgenus Polypompholyx (Lentibulariaceae) we studied branching of stolons by scanning electron microscopy, statistically investigated correlations of stolon types and other traits across 56 species, and evaluated seedling development and process morphological aspects. Some results were compared to the sister genera Pinguicula and Genlisea. A key to nine stolon types in Polypompholyx is provided. Predominant stolon types were rhizoids, runner stolons with rhizoids on nodes, and runner stolons without rhizoids on nodes but with bladders on internodes. Stolon types were taxonomically relevant and correlated to the distribution/climate. They obviously diverged with speciation events in Australia. Examined seedlings of Genlisea and Polypompholyx showed similar developmental patterns. Stolons were homologous to traps and leaves. Selected subterranean organs contained specific but similar process combinations of roots, shoots and/or leaves. We assume the Genlisea-Utricularia ancestor trap included processes of a Pinguicula root and leaf. [ABSTRACT FROM AUTHOR]

The endangered epiphytic orchid, Dendrobium chrysotoxum, is known for its ornamental and medicinal uses. However, knowledge of this orchid's symbiotic seed germination, protocorm anatomy, and developmental morphology is completely unknown. In this study, we investigated the process of protocorm development of D. chrysotoxum during symbiotic germination using anatomical technologies and scanning electron microscopy. There are six development stages that were morphologically and anatomically defined during symbiotic seed germination. The embryo transformed into a protocorm at stage two, and a protrusion developed from the top of the protocorm at stage three and elongated to form the cotyledon at stage four. The stem apical meristem (SAM) was initiated at stage three and well developed at stage four. The first leaf and the root appeared at stages five and six, respectively. The hyphae entered through the micropylar end of the seed at stage one and then invaded the protocorm through rhizoids when rhizoids formed. Invading fungal hyphae colonized the inner cortex at the base of protocorms, formed pelotons, and were digested by host cells later. We conclude that protocorm development is programmed by the embryo, which determines the structure and function of the protocorm. The two developmental zones in a polarized D. chrysotoxum embryo include the smaller cells zone, which forms the cotyledon and a shoot apical meristem at the apical end, and the larger cells zone, which forms the mycorrhiza to house the symbiont at the basal end. These results will provide important insights for further research on the mechanisms underlying orchid-fungi symbiosis and enhance the understanding of orchid evolution. [ABSTRACT FROM AUTHOR]

A new subtidal species of Dasya is reported from offshore algal plains of Puerto Rico and Grenada in the Caribbean. Closely invested with pigmented lateral branchlets giving the alga a shaggy appearance, the species bears close resemblance and genetic affinity to the Bermudian Dasya cryptica and a superficial resemblance to Pacific D. anastomosans. The new species differs from all known Atlantic congeners as well as non-Atlantic members of the "Dasya cryptica complex" both genetically and in possessing rhizoids among its pericentral and enlarged inner cortical cells. [ABSTRACT FROM AUTHOR]

The evolutionary history of the symbiotic association between arbuscular mycorrhizal fungi (AMF) and embryophytes dates back to the Devonian period. Previous ecological and physiological studies have described the presence of arbuscules, inter- and intracellular hyphae, vesicles, coils and spores, in liverworts and hornworts, which are considered absent in mosses. This study aimed to report the presence of AMF in a community of bryophytes (mosses and liverworts) from Punta Lara Natural Reserve, Argentina. Senescent and green sections of gametophytes were stained and, following microscopic observation, revealed AMF structures. We found intracellular hyphae, vesicles, spores and sporocarps associated with thallus and rhizoids of mosses and liverworts and senescent moss caulidia. The morphological characterization of spores resulted in the determination of Rhizophagus intraradices and Dominikia aurea. The species D. aurea is reported for the first time for Argentina. Sequencing of the D1 variable domain of the LSUrDNA from AMF spores mixes plus hyphae resulted in high similitude to the Dominikia sequences available from NCBI. This study reported the presence of AMF associated with declining and senescent gametophytes of bryophytes (mosses and liverworts) in a Natural Reserve in Argentina. These findings open up new lines of study, which should further investigate these associations and their diversity, physiology and significance. [ABSTRACT FROM AUTHOR]

A NIMA-related protein kinase, MpNEK1, directs tip growth of rhizoids through microtubule depolymerization in a liverwort Marchantia polymorpha. The Mpnek1 knockouts were shown to develop curly and spiral rhizoids due to the fluctuated direction of growth. Still, physiological roles and mechanisms of MpNEK1-dependent rhizoid tip growth remain to be clarified. Here, we developed novel culture methods to further study rhizoid growth of M. polymorpha, in which plants were grown on vertical plates. We applied the established methods to investigate MpNEK1 function in rhizoid growth. Rhizoids of the wild-type and Mpnek1 plants grew toward the gravity. The aerial rhizoids were longer in Mpnek1 than in the wild type. When the rhizoids were grown on the surface of a cellophane sheet, rhizoid length was comparable between the wild type and Mpnek1, whereas Mpnek1 developed more rhizoids compared to the wild type. We also applied gellan gum, which is more transparent than agar, to analyze rhizoids grown in the medium. Rhizoids of Mpnek1 displayed defect on entering into the solid medium. These results suggest that Mpnek1 rhizoids have the deficiency in invasive tip growth. Thus, stable directional growth is important for rhizoids to get into the soil to anchor plant body and to adsorb water and nutrients. Collectively, our newly designed growth systems are valuable for analyzing rhizoid growth. [ABSTRACT FROM AUTHOR]

Marchantiopsida (complex thalloid liverworts) are one of the earliest lineages of embryophytes (land plants), and well‐known for their air pores and chambers, pegged rhizoids, and absence of organellular RNA editing sites. Despite their importance to an understanding of early embryophyte evolution, many key nodes within this class remain poorly resolved, owing to the paucity of genetic loci previously available for phylogenetic analyses. Here, we sequenced 54 plastomes, representing 28 genera, nearly all families, and all orders of Marchantiopsida. Based on these plastomes, we present a hypothesis of deep relationships within the class, and make the first investigations of gene contents and synteny. Overall, the Marchantiopsida plastomes were well‐conserved, with the exception of the genus Cyathodium that has plastomes with higher GC content, fewer single sequence repeats (SSRs), and more structural variations, implying that this genus might possess RNA editing sites. Abundant repetitive elements and six highly divergent regions were identified as suitable for future infrafamilial taxonomic studies. The phylogenetic topology of Sphaerocarpales, Neohodgsoniales and Blasiales within Marchantiopsida was essentially congruent with previous studies but generally we obtained higher support values. Based on molecular evidence and previous morphological studies, we include Lunulariales in Marchantiales and suggest the retention of narrowed delimitation of monotypic families. The phylogenetic relationships within Marchantiales were better resolved, and 13 monophyletic families were recovered. Our analyses confirmed that the loss of intron 2 of ycf3 is a synapomorphy of Marchantiidae. Finally, we propose a new genus, Asterellopsis (Aytoniaceae), and present an updated classification of Marchantiopsida. The highly supported phylogenetic backbone provided here establishes a framework for future comparative and evolutionary studies of the complex thalloid liverworts. [ABSTRACT FROM AUTHOR]

Background and aims: Zephyranthes bifida is a native species of the Pampas ecoregion, with ornamental and medicinal potential. In this work, the seedling was studied for the first time and its seeds were characterized. The objectives were to describe the cotyledon and the first leaf and to provide some anatomical characteristics, as well as to provide information about the embryo/endosperm relationship and the type of reserve substances in the seed. M&M: Seed reserve substances were determined by histochemical tests and the embryo/endosperm surface ratio was obtained with ImageJ. In seedlings, morphological structures were described, using Tillich's terminology (1995; 2007), and some anatomical characteristics. Phenological stages were established for ten days from germination. Results and conclusions: Lipid and protein and lack of starch were determined in embryo and endosperm. In seedlings, the cotyledon is subdivided into a hypophyll and a hyperphyll. Hypophyll presents a ring through which the first eophyll emerges. The distal part of the cotyledonary hyperphyll is completely inserted in the seed, has a haustorial function and has two vascular bundles. Proximal part of cotyledonary hyperphyll has photosynthetic activity and has two vascular bundles too. In the first eophyll, hyperphyll has three vascular bundles. The primary root is attached to the base of the cotyledon through a very short hypocotyl, which in its basal part has rhizoids. Four stages were defined during germination from the emergence of hypophyll, hyperphyll and first eophyll. [ABSTRACT FROM AUTHOR]

The term 'eucheumatoids' designates a group of genera in the family Solieriaceae that are the source of some of the most valuable algal products in cultivation. While economically important in the tropics, much of its taxonomy is yet to be fully resolved. The eucheumatoid species Mimica arnoldii is a Batesian mimic of corals that was recently transferred to its own genus from Eucheuma based primarily on peculiarities of habit and a lack of medullary rhizoids, in contrast to the generitype Eucheuma denticulatum that has the latter. We studied the diversity of Mimica arnoldii from samples collected in the Philippines to determine their genetic variation, relationships to other eucheumatoids, and whether its two distinct morphological expressions, which have been named as varieties, are genetically different. We produced a phylogeny using a three-gene concatenated dataset, and used the variable mitochondrial cox2-3 spacer to determine intraspecific variation and the degree of correlation between sequence-variation and varietal status. Our results showed that Mimica is a distinct genus, and that intra-specific molecular data did not correspond to the morphology-based varieties, although it did correlate with geographical distribution. Our results also indicate that Kappaphycus, as presently circumscribed, contains species with (Kappahycus alvarezii, K. striatus and K. malesianus) and without (Kapppahycus cottonii) internal medullary hyphal core, and that K. cottonii is sister to the remaining Kappaphycus species. We thus propose Kappaphycopsis gen. nov. for K. cottonii for the species of Kappaphycus without internal medullary rhizoids (anaxiferous). [ABSTRACT FROM AUTHOR]

Monitoring electrical signals in plants allows the examination of their acute and chronic physiological changes and responses to stimuli. Understanding how plant roots/rhizoids respond to chemical cues in their environment will provide insight into how these structures acquire resources. Chronic exposure to L-glutamate alters root growth and is known to alter Ca2+ flux inside roots. The ionic flux can be detected by electrical changes. A rapid and relatively easy approach is presented to screen the electrical sensitivity of roots/rhizoids to compounds such as amino acids and known agonists/antagonists to receptors and ion channels. The approach uses a background-flow system of basal salt or water; then, the administered compounds are added to the roots/rhizoids while monitoring their electrical responses. As a proof of concept, the response to flow-through of glutamate (1 mM) was targeted at the root/rhizoids of three plants (Arabidopsis thaliana, Pisum sativum and Marchantia inflexa). Both Arabidopsis thaliana and Pisum sativum produced rapid depolarization upon exposure to glutamate, while M. inflexa did not show an electrical response. In some experiments, simultaneous recordings with impedance measures for acute changes and glass electrodes for chronic electrical potential changes were used. The effect of potassium chloride (300 mM) as a depolarizing stimulus produced responses in both P. sativum and M. inflexa. The protocol presented can be used to screen various compounds in a relatively rapid manner for responsiveness by the roots/rhizoids of plants. [ABSTRACT FROM AUTHOR]

The colonization of land by ancestors of embryophyte plants was one of the most significant evolutionary events in the history of life on earth. The lack of a buffering aquatic environment necessitated adaptations for coping with novel abiotic challenges, particularly high light intensities and desiccation as well as the formation of novel anchoring structures. Bryophytes mark the transition from freshwater to terrestrial habitats and form adaptive features such as rhizoids for soil contact and water uptake, devices for gas exchange along with protective and repellent surface layers. The amphibious liverwort Riccia fluitans can grow as a land form (LF) or water form (WF) and was employed to analyze these critical traits in two different habitats. A combination of light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies was conducted to characterize and compare WF and LF morphologies. A complete phenotypic adaptation of a WF plant to a terrestrial habitat is accomplished within 15 days after the transition. Stable transgenic R. fluitans lines expressing GFP-TUBULIN and mCherry proteins were generated to study cell division and differentiation processes and revealed a higher cell division activity in enlarged meristematic regions at LF apical notches. Morphological studies demonstrated that the R. fluitans WF initiates air pore formation. However, these pores are arrested at an early four cell stage and do not develop further into open pores that could mediate gas exchange. Similarly, also arrested rhizoid initial cells are formed in the WF, which exhibit a distinctive morphology compared to other ventral epidermal cells. Furthermore, we detected that the LF thallus has a reduced surface permeability compared to the WF, likely mediated by formation of thicker LF cell walls and a distinct cuticle compared to the WF. Our R. fluitans developmental plasticity studies can serve as a basis to further investigate in a single genotype the molecular mechanisms of adaptations essential for plants during the conquest of land. [ABSTRACT FROM AUTHOR]

The colonization of land by ancestors of embryophyte plants was one of the most significant evolutionary events in the history of life on earth. The lack of a buffering aquatic environment necessitated adaptations for coping with novel abiotic challenges, particularly high light intensities and desiccation as well as the formation of novel anchoring structures. Bryophytes mark the transition from freshwater to terrestrial habitats and form adaptive features such as rhizoids for soil contact and water uptake, devices for gas exchange along with protective and repellent surface layers. The amphibious liverwort Riccia fluitans can grow as a land form (LF) or water form (WF) and was employed to analyze these critical traits in two different habitats. A combination of light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies was conducted to characterize and compare WF and LF morphologies. A complete phenotypic adaptation of a WF plant to a terrestrial habitat is accomplished within 15 days after the transition. Stable transgenic R. fluitans lines expressing GFP-TUBULIN and mCherry proteins were generated to study cell division and differentiation processes and revealed a higher cell division activity in enlarged meristematic regions at LF apical notches. Morphological studies demonstrated that the R. fluitans WF initiates air pore formation. However, these pores are arrested at an early four cell stage and do not develop further into open pores that could mediate gas exchange. Similarly, also arrested rhizoid initial cells are formed in the WF, which exhibit a distinctive morphology compared to other ventral epidermal cells. Furthermore, we detected that the LF thallus has a reduced surface permeability compared to the WF, likely mediated by formation of thicker LF cell walls and a distinct cuticle compared to the WF. Our R. fluitans developmental plasticity studies can serve as a basis to further investigate in a single genotype the molecular mechanisms of adaptations essential for plants during the conquest of land.

With differentiated tissues and organs, a high-level eukaryotic macroalga Lanceaphyton xiaojiangensis n. gen. n. sp. lived on the middle–late Ediacaran (ca. 560–551 Ma) seafloor in South China. Its body had a pith (perhaps mechanical tissue) and outer tissue (perhaps epidermis and/or cortex). The lance-like macroalga consists of an unbranching thallus that grew over the sediment surface for sunlight and a holdfast grown into sediments to keep the thallus fixed on the seafloor. The pithy stipe (lower thallus) might have served to support the upper pithless thallus for photosynthesis. The holdfast is composed of a tapering pithy rhizome growing down into the sediments, with many filamentous pithless rhizoids dispersedly growing within the sediments. With the differentiated tissues and organs, especially the pith accounting for about half of the width of the rhizome and stipe, Lanceaphyton n. gen. was a high-level eukaryotic macroalga, similar to phaeophytes in morphological features, but further research is needed on its microstructural details. The pithy macroalga shows that the macroalgal pith had emerged in the Ediacaran. UUID: http://zoobank.org/bc924c5c-84e4-4170-9ca1-caee0d56c6d5. [ABSTRACT FROM AUTHOR]

The chytrids (phylum Chytridiomycota) are a major fungal lineage of ecological and evolutionary importance. Despite their importance, many fundamental aspects of chytrid developmental and cell biology remain poorly understood. To address these knowledge gaps, we combined quantitative volume electron microscopy and comparative transcriptome profiling to create an 'atlas' of the cellular and molecular basis of the chytrid life cycle, using the model chytrid Rhizoclosmatium globosum. From our developmental atlas, we describe the transition from the transcriptionally inactive free- swimming zoospore to the more biologically complex germling, and show that lipid processing is multifaceted and dynamic throughout the life cycle. We demonstrate that the chytrid apophysis is a compartmentalised site of high intracellular trafficking, linking the feeding/attaching rhizoids to the reproductive zoosporangium, and constituting division of labour in the chytrid cell plan. We provide evidence that during zoosporogenesis, zoospores display amoeboid morphologies and exhibit endocytotic cargo transport from the interstitial maternal cytoplasm. Taken together, our results reveal insights into chytrid developmental biology and provide a basis for future investigations into non- dikaryan fungal cell biology. [ABSTRACT FROM AUTHOR]

The bryophilous ascomycete Octospora meslinii is a rarely reported species growing exclusively in cushions of the saxicolous moss Grimmia pulvinata. The taxon has been misunderstood in the past and hitherto reliably only reported from France and Germany. Many recent collections from Hungary have made it possible to get a better understanding of O. meslinii, which is comprehensively described and illustrated in this paper. Because of the lack of original material, we designate an illustration in the protologue as the lectotype and one of the recent collections as the epitype of this fungus. Octospora meslinii is compared with other species of Octospora growing in the same type of habitat or having similar ascospores. The most closely related species to O. meslinii is O. pseudoampezzana. Both share apothecia with blackish pigmentation, a unique feature compared to bryophilous Pezizales as a whole, ellipsoid ascospores ornamented with isolated warts, moss hosts in the family Grimmiaceae, and the infection inducing galls on the rhizoids. A phylogenetic analysis using the EF1 α LSU and SSU rDNA loci confirms our morphological findings showing that O. meslinii forms a monophyletic clade with O. pseudoampezzana, whereas other species with which O. meslinii was confused in the past, e.g. O. similis, are related only distantly. [ABSTRACT FROM AUTHOR]

Bare sandy flats at and below low tide level of the Wadden Sea (eastern North Sea, European Atlantic) were observed in 2020 to have been invaded by an introduced grass-like alga, Vaucheria cf. velutina (Xanthophyceae). A dense algal turf accumulated and stabilized mud, where resident seniors of the lugworm Arenicola marina had reworked rippled sand. Algae and worms were incompatible. Initially, rising patches with algal turf alternated with bare pits where lugworms crowded. Their bioturbation inhibited young algae, while the felt of established algal rhizoids clogged feeding funnels of worm burrows. Eventually, a mosaic pattern of competitors gave way to a coherent algal turf without lugworms. Concomitantly, a rich small-sized benthic fauna took advantage of the novel algal turf. This exotic Vaucheria may have the potential for drastically altering the ecological web at the lower shore. [ABSTRACT FROM AUTHOR]

The genus Ramicrusta (order Peyssonneliales) is a new record for Micronesia, with range expansions of Ramicrusta fujiiana and R. lateralis to Guam. In addition, four species (Ramicrusta adjoulanensis, R. asanitensis, R. labtasiensis, and R. taogamensis) are newly described from Guam using molecular and anatomical characters. Ramicrusta lateralis specimens from Guam share most anatomical features with the holotype description from Vanuatu, but the plants from Guam are more tightly adherent, rigid, and robust than those of Vanuatu. Ramicrusta adjoulanensis possesses a well-developed epithallus with frequent cell fusions, secondary pit connections, and lacking hair bases or trichocytes, similar to Ramicrusta bonairensis. Ramicrusta adjoulanensis differs from other Ramicrusta species in having occasionally free margins and being attached by frequently produced, relatively long rhizoids (75–100 μm long). Ramicrusta asanitensis shares features with many other species, but the thickness of the crust (upwards of 2 mm thick), heavy calcification in the epithallus, and the extent of secondary, tertiary, and quaternary growth, differentiate it from other Ramicrusta species. Ramicrusta labtasiensis shares features with its close relative Ramicrusta lateralis but possesses frequent, robust, and relatively long rhizoids (75–95 μm long) throughout its entire undersurface. Ramicrusta taogamensis resembles its close relative Ramicrusta appressa but is primarily distinguished by its generally well-developed epithallus with occasional secondary pit connections and cell fusions. The six species reported here make Guam equal to Vanuatu in currently having the highest known species richness of Ramicrusta in the world. [ABSTRACT FROM AUTHOR]

Agrobacterium -mediated transient gene expression is a rapid and useful approach for characterizing functions of gene products in planta. However, the practicability of the method in the model liverwort Marchantia polymorpha has not yet been thoroughly described. Here we report a simple and robust method for Agrobacterium -mediated transient transformation of Marchantia thalli and its applicability. When thalli of M. polymorpha were co-cultured with Agrobacterium tumefaciens carrying β-glucuronidase (GUS) genes, GUS staining was observed primarily in assimilatory filaments and rhizoids. GUS activity was detected 2 days after infection and saturated 3 days after infection. We were able to transiently co-express fluorescently tagged proteins with proper localizations. Furthermore, we demonstrate that our method can be used as a novel pathosystem to study liverwort–bacteria interactions. We also provide evidence that air chambers support bacterial colonization. [ABSTRACT FROM AUTHOR]

Chenia leptophylla is reported new to North Carolina based on a single population in Harnett County. Selected locations of global distribution and all known state distribution within the U.S.A. are presented with commonly used synonyms. A brief description of newly discovered foliar rhizoids and phenological forms as observed in North Carolina plants is included. [ABSTRACT FROM AUTHOR]

Four new species within the genus Absidia , A. globospora , A. medulla , A. turgida , and A. zonata , are proposed based on a combination of morphological traits, physiological features, and molecular evidences. A. globospora is characterized by globose sporangiospores, a 1.0- to 3.5-μm-long papillary projection on columellae, and sympodial sporangiophores. A. medulla is characterized by cylindrical to oval sporangiospores, a 1.0- to 4.5-μm-long bacilliform projection on columellae, and spine-like rhizoids. A. turgida is characterized by variable sporangiospores, up to 9.5-μm-long clavate projections on columellae, and swollen top of the projection and inflated hyphae. A. zonata is characterized by cylindrical to oval sporangiospores, a 2.0- to 3.5-μm-long spinous projection on columellae, and as many as eight whorled sporangiophores. Phylogenetic analyses based on sequences of internal transcribed spacer rDNA and D1–D2 domains of LSU rDNA support the novelty of these four species within the Absidia. All new species are illustrated, and an identification key to all the known species of Absidia in China is included. [ABSTRACT FROM AUTHOR]

The unique features of embryo development, morphological and anatomical shoot structure, and the root system in one of the smallest annual plants mousetail at the earliest and following stages of ontogenesis are shown. The correspondence of revealed structures (presence of collet with rhizoids, aerenchyma in the primary cortex of the hypocotyl and adventive roots, secondary homorhizia, plane apical meristem together with obligate rozett structure of the main shoot) and of polyvariant ontogenesis (spring ephemeral variant and variant with overwintering) and longevity of life circle phases to the ecological features of the species—hygrophyly, minimal threshold size (minimal number of metamers of the main shoot axis)—are discussed. [ABSTRACT FROM AUTHOR]

Tip-growth is a mode of polarized cell expansion where incorporation of new membrane and wall is stably restricted to a single, small domain of the cell surface resulting in the formation of a tubular projection that extends away from the body of the cell. The organization of the microtubule cytoskeleton is conserved among tip-growing cells of land plants: bundles of microtubules run longitudinally along the non-growing shank and a network of fine microtubules grow into the apical dome where growth occurs. Together, these microtubule networks control the stable positioning of the growth site at the cell surface. This conserved dynamic organization is required for the spatial stability of tip-growth, as demonstrated by the formation of sinuous tip-growing cells upon treatment with microtubule-stabilizing or microtubule-destabilizing drugs. Microtubule associated proteins (MAPs) that either stabilize or destabilize microtubule networks are required for the maintenance of stable tip-growth in root hairs of flowering plants. NIMA RELATED KINASE (NEK) is a MAP that destabilizes microtubule growing ends in the apical dome of tip-growing rhizoid cells in the liverwort Marchantia polymorpha. We hypothesized that both microtubule stabilizing and destabilizing MAPs are required for the maintenance of the stable tip-growth in liverworts. To identify genes encoding microtubule-stabilizing and microtubule-destabilizing activities we generated 120,000 UV-B mutagenized and 336,000 T-DNA transformed Marchantia polymorpha plants and screened for defective rhizoid phenotypes. We identified 119 mutants and retained 30 mutants in which the sinuous rhizoid phenotype was inherited. The 30 mutants were classified into at least 4 linkage groups. Characterisation of two of the linkage groups showed that MAP genes–WAVE DAMPENED2-LIKE (WDL) and NIMA-RELATED KINASE (NEK)–are required to stabilize the site of tip growth in elongating rhizoids. Furthermore, we show that MpWDL is required for the formation of a bundled array of parallel and longitudinally orientated microtubules in the non-growing shank of rhizoids where MpWDL-YFP localizes to microtubule bundles. We propose a model where the opposite functions of MpWDL and MpNEK on microtubule bundling are spatially separated and promote tip-growth spatial stability. Author summary: Plant cells control where they grow by adding membrane and cell wall material to a defined area of their surface. In particular, filamentous rooting cells develop the cellular projections essential to their function by restricting cell expansion to a stable domain of their surface. The spatial stability of this mechanism known as tip-growth defines the final shape of the cellular projections–straight projections form from stable tip-growth, while wavy or bifurcating projections form from unstable tip-growth. Microtubules are known to regulate tip-growth stability. Both microtubule stabilisation and destabilisation leads to unstable tip-growth. We have discovered two proteins that associate with microtubules, control their stability and are required for stabilizing tip-growth in the common liverwort. The first protein is known to destabilize microtubules in the tip of filamentous rooting cells of the common liverwort, and we found the second protein to stabilize, or bundle, microtubules in their shank. This is important because it is the first protein found to stabilize microtubules in the common liverwort and because it is the first time a protein stabilizing microtubules in rooting cells of plants is shown to localize separately from proteins that destabilizes microtubules. We propose that tip-growth stability requires the opposite functions of these two microtubule associated protein to be spatially separated. [ABSTRACT FROM AUTHOR]

The recent segregation of 12 genera in the tribe Streblocladieae suggests that the taxonomy of some species belonging to Polysiphonia sensu lato is updated with the transfer and the proposal of new combinations. Accordingly, six new additions to the tribe Streblocladieae on the basis of morphological and molecular analyses are presented as a consequence of this new segregation. These additions include the description of the new species Carradoriella platensis sp. nov., the proposal of the following new combinations Eutrichosiphonia paniculata comb. nov., E. tapinocarpa comb. nov., and the reinstatement of Vertebrata curta, V. decipiens, and V. patersonis. Additionally, our morphological observations identified additional diagnostic features for two genera of the Streblocladieae. Carradoriella has branches with sexual reproductive structures arranged adaxially on branchlets, and the recently described Eutrichosiphonia has rhizoids with multicellular digitate haptera. Our study gives insights in regards to the distribution, the diagnostic features for delimiting genera morphologically, and the molecular evolutionary relationships in the Streblocladieae. [ABSTRACT FROM AUTHOR]

The new genus Protoharpanthus is described from the Salween River Basin in the Hengduan Mountains, Sino-Himalaya. The genus superficially resembles Lophocolea or slightly even Calypogeia, but phylogenetically is quite far from both and belongs to the oligotypic Harpanthaceae. The new genus is a shining example of parallelism in the evolution of liverworts and is characterized by succubous and shortly bilobed leaves with a differentiated margin of elongate cells, finely verruculose leaf cuticle, distinct stem hyalodermis with large trigones in the outer cells of the stem cross section, bilobed underleaves, rhizoids restricted to underleaf bases and exclusively ventral intercalary branching. In both phylogenetic and phytogeographical senses this genus is a relict in the Sino-Himalayan bryoflora. [ABSTRACT FROM AUTHOR]

Ethylene is a gaseous phytohormone involved in various physiological processes, including fruit ripening, senescence, root hair development and stress responses. Recent genomics studies have suggested that most homologous genes of ethylene biosynthesis and signaling are conserved from algae to angiosperms, whereas the function and biosynthesis of ethylene remain unknown in basal plants. Here, we examined the physiological effects of ethylene, an ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC) and an inhibitor of ethylene perception, silver thiosulfate (STS), in a basal land plant, Marchantia polymorpha. M. polymorpha plants biosynthesized ethylene, and treatment with high concentrations of ACC slightly promoted ethylene production. ACC remarkably suppressed the growth of thalli (vegetative organs) and rhizoids (root-hair-like cells), whereas exogenous ethylene slightly promoted thallus growth. STS suppressed thallus growth and induced ectopic rhizoid formation on the dorsal surface of thalli. Thus, ACC and ethylene have different effects on the vegetative growth of M. polymorpha. We generated single and double mutants of ACC synthase-like (ACSL) genes, Mp ACSL1 and Mp ACSL2. The mutants did not show obvious defects in thallus growth, ACC content and ethylene production, indicating that Mp ACSL genes are not essential for the vegetative growth and biosynthesis of ACC and ethylene. Gene expression analysis suggested the involvement of Mp ACSL1 and Mp ACSL2 in stress responses. Collectively, our results imply ethylene-independent function of ACC and the absence of ACC-mediated ethylene biosynthesis in M. polymorpha. [ABSTRACT FROM AUTHOR]

The species within the family Cunninghamellaceae are widely distributed and produce important metabolites. Morphological studies along with a molecular phylogeny based on the internal transcribed spacer (ITS) and large subunit (LSU) of ribosomal DNA revealed two new species in this family from soils in China, that is, Absidia ovalispora sp. nov. and Cunninghamella globospora sp. nov. The former is phylogenetically closely related to Absidia koreana, but morphologically differs in sporangiospores, sporangia, sporangiophores, columellae, collars, and rhizoids. The latter is phylogenetically closely related to Cunninghamella intermedia, but morphologically differs in sporangiola and colonies. They were described and illustrated. [ABSTRACT FROM AUTHOR]

A key adaptation of plants to life on land is the formation of water-conducting cells (WCCs) for efficient long-distance water transport. Based on morphological analyses it is thought that WCCs have evolved independently on multiple occasions. For example, WCCs have been lost in all but a few lineages of bryophytes but, strikingly, within the liverworts a derived group, the complex thalloids, has evolved a novel externalized water-conducting tissue composed of reinforced, hollow cells termed pegged rhizoids. Here, we show that pegged rhizoid differentiation in Marchantia polymorpha is controlled by orthologs of the ZHOUPI and ICE bHLH transcription factors required for endosperm cell death in Arabidopsis seeds. By contrast, pegged rhizoid development was not affected by disruption of Mp NAC5 , the Marchantia ortholog of the VND genes that control WCC formation in flowering plants. We characterize the rapid, genetically controlled programmed cell death process that pegged rhizoids undergo to terminate cellular differentiation and identify a corresponding upregulation of conserved putative plant cell death effector genes. Lastly, we show that ectopic expression of Mp ZOU1 increases production of pegged rhizoids and enhances drought tolerance. Our results support that pegged rhizoids evolved independently of other WCCs. We suggest that elements of the genetic control of developmental cell death are conserved throughout land plants and that the ZHOUPI/ICE regulatory module has been independently recruited to promote cell wall modification and programmed cell death in liverwort rhizoids and in the endosperm of flowering plant seed. [Display omitted] • Marchantia encodes orthologs of the bHLH transcription factors ZOU and ICE • MpZOU1 interacting with MpICE1 promotes terminal differentiation of pegged rhizoids • Terminal differentiation of pegged rhizoids involves a canonical cell death program • Increased abundance of pegged rhizoids enhances drought resistance of thalli Lu et al. show that the bHLH transcription factor MpZHOUPI promotes cell wall reinforcement and programmed cell death in pegged rhizoids of the liverwort Marchantia polymorpha. Dead reinforced cells are also typical of vascular plants' xylem, revealing a striking case of convergent evolution of water-conducting cells in different plant lineages. [ABSTRACT FROM AUTHOR]

• Didymoglossum includes small, epiphytic or epilithic filmy ferns. • The false veins of the laminae are formed by macrosclereids and/or stegmata. • The cuticle and mucilaginous pores are evidenced. • The mucilaginous fibres in phloem are reported. • The basal parts of the involucre are pluristratified, with vascular bundles. Didymoglossum (Hymenophyllaceae) is a monophyletic genus that includes small, epiphytic or epilithic plants. Three morphologically very similar species are found in the southern sector of the Yungas and Parana forests: D. hymenoides, D. krausii and D. reptans. The aim of this research was to characterise the morphoanatomy to better delimitate the taxa. Also, to evidence the presence of fungal endophytes. Conventional histological techniques were applied to fresh and FAA-fixed material. The anatomical structure of the different organs, in the three species, is similar; with collateral protostelic rhizomes, covered with simple or branched rhizoids; stipes teretes with glandular trichomes; uniestratified laminae formed by epidermal cells, with collateral vascular bundles; false veins formed by macrosclereids and stegmata or only by macrosclereids. The eglandular and glandular trichomes on the lamina differ in the species studied. The basal and middle portion of the involucre are pluristratified, with a vascular bundle at each margin, while the apical portion is formed by a one layer of epidermal cells; the receptacle is pluristratified with glandular trichomes on its surface. The presence of stegmata, collenchymatous tissue, sclerenchyma, mucilage fibers in phloem, pores in lamina and cuticle on the epidermis is evidenced and reported. Septate fungal endophytes were observed in epidermal cells of the rhizome, stipe and lamina of D. krausii and D. reptans. Species are differentiated by the following characters: shape of the lamina, diameter of the rhizome, number of false veins and the types of trichomes and pores. A key for the studied species is presented. [Display omitted] [ABSTRACT FROM AUTHOR]

Mycothalli, symbioses between liverworts and soil fungi, have not previously been recorded in the Arctic. Here, 13 species of leafy liverwort from west Spitsbergen in the High Arctic are examined for the symbiosis using epifluorescence microscopy and sequencing of fungal ribosomal (r)RNA genes amplified from plant tissues. Microscopy showed that intracellular hyphal coils, key indicators of the symbiosis, were frequent (>40% stem length colonized) in nine species of liverwort in the families Anastrophyllaceae, Lophoziaceae, Cephaloziellaceae, Cephaloziaceae and Scapaniaceae, with hyphae occurring frequently (>40% cells occupied) in the rhizoids of 10 species in the same families. Dark septate hyphae, apparently formed by ascomycetes, were frequent on the stems of members of the Anastrophyllaceae, Cephaloziellaceae and Cephaloziaceae, and typically those growing on acidic mine tailings. Sequencing of fungal rRNA genes showed the presence of nine distinct groups (based on a 3% cut-off for ITS sequence divergence) of the basidiomycete Serendipita in the Anastrophyllaceae and Lophoziaceae, with ordinations and correlative analyses showing the presence of the genus to be positively associated with the frequency of hyphal coils, the occurrence of which was positively associated with edaphic factors (soil δ15N value and concentrations of moisture, nitrogen, carbon and organic matter). We propose that the frequency of mycothalli in leafy liverworts on west Spitsbergen, which is an order of magnitude higher than at lower latitudes, may arise from benefits conferred by mycobionts on their hosts in the harsh environment of the High Arctic. [ABSTRACT FROM AUTHOR]

The reduced density of the autogenous bone around metal medical implants forces joint replacement patients to undergo revision surgery. The loss of bone density is caused by a significant difference in the elastic modulus between implants and autogenous bone. Various studies have attempted to reduce the elastic modulus of the implant to close the large gap in the two moduli. Porous metal is a promising material for reducing the elastic modulus of implants, but it is difficult to fabricate a closed-cell structure like bone using conventional porous metal fabrication methods. In this study, porous Ti-6Al-4V was prepared by selective laser melting, then its porosity was evaluated by X-ray computed tomography. Additionally, tensile test specimens of the porous structure were prepared and the effect of pores on the tensile properties was evaluated. Depending on the energy density, the structure of the porous body was found to form both closed- and open-cell structures. In the tensile specimens that showed the most favorable results, the elastic modulus was reduced by approximately 90%, and the tensile strength exceeded that of the annealed material. This indicates that a metal implant that has a low elastic modulus while maintaining strength can be obtained. [ABSTRACT FROM AUTHOR]

Key to the ecological prominence of fungi is their distinctive cell biology, our understanding of which has been principally based on dikaryan hyphal and yeast forms. The early-diverging Chytridiomycota (chytrids) are ecologically important and a significant component of fungal diversity, yet their cell biology remains poorly understood. Unlike dikaryan hyphae, chytrids typically attach to substrates and feed osmotrophically via anucleate rhizoids. The evolution of fungal hyphae appears to have occurred from rhizoid-bearing lineages and it has been hypothesized that a rhizoid-like structure was the precursor to multicellular hyphae. Here, we show in a unicellular chytrid, Rhizoclosmatium globosum, that rhizoid development exhibits striking similarities with dikaryan hyphae and is adaptive to resource availability. Rhizoid morphogenesis exhibits analogous patterns to hyphal growth and is controlled by β-glucan-dependent cell wall synthesis and actin polymerization. Chytrid rhizoids growing from individual cells also demonstrate adaptive morphological plasticity in response to resource availability, developing a searching phenotype when carbon starved and spatial differentiation when interacting with particulate organic matter. We demonstrate that the adaptive cell biology and associated developmental plasticity considered characteristic of hyphal fungi are shared more widely across the Kingdom Fungi and therefore could be conserved from their most recent common ancestor. [ABSTRACT FROM AUTHOR]

Prasinophytes (Chlorophyta) are a diverse, paraphyletic group of planktonic microalgae for which benthic species are largely unknown. Here, we report a sand‐dwelling, marine prasinophyte with several novel features observed in clonal cultures established from numerous locations around Australia. The new genus and species, which we name Microrhizoidea pickettheapsiorum (Mamiellophyceae), alternates between a benthic palmelloid colony, where cell division occurs, and a planktonic flagellate. Flagellates are short lived, settle and quickly resorb their flagella, the basal bodies then nucleate novel tubular appendages, termed "microrhizoids", that lack an axoneme and function to anchor benthic cells to the substratum. To our knowledge, microrhizoids have not been observed in any other green alga or protist, are slightly smaller in diameter than flagella, generally contain nine microtubules, are long (3–5 times the length of flagella) and are not encased in scales. Following settlement, cell divisions result in a loose, palmelloid colony, each cell connected to the substratum by two microrhizoids. Flagellates are round to bean‐shaped with two long, slightly uneven flagella. Both benthic cells and flagellates, along with their flagella, are encased in thin scales. Phylogenies based on the complete chloroplast genome of Microrhizoidea show that it is clearly a member of the Mamiellophyceae, most closely related to Dolichomastix tenuilepsis. More taxon‐rich phylogenetic analyses of the 18S rRNA gene, including metabarcodes from the Tara Oceans and Ocean Sampling Day projects, confidently show the distinctive nature of Microrhizoidea, and that the described biodiversity of the Mamiellophyceae is a fraction of its real biodiversity. The discovery of a largely benthic prasinophyte changes our perspective on this group of algae and, along with the observation of other potential benthic lineages in environmental sequences, illustrates that benthic habitats can be a rich ground for algal biodiscovery. [ABSTRACT FROM AUTHOR]

The advantage of filamentous growth to the fungal lifestyle is so great that it arose multiple times. Most zoosporic fungi from phylum Chytridiomycota exhibit a monocentric thallus form consisting of anucleate filamentous rhizoids that anchor reproductive sporangia to substrata and absorb nutrients. Actin function during polarized growth and cytokinesis is well documented across eukaryotes, but its role in sculpting nonhyphal, nonyeast fungal cells is unknown. We sought to provide a basis for comparing actin organization among major fungal lineages and to investigate the effects of actin disruption on morphogenesis in a monocentric thallus. Using fluorescence microscopy, we observed fixed, rhodamine phalloidin–stained actin in chemically fixed Chytriomyces hyalinus, exemplifying monocentric thallus development within the diverse, zoosporic phylum Chytridiomycota. We also compared rhizoid lengths and rhizoid branching of thalli incubated with the actin inhibitor latrunculin B to determine the effects of actin disruption on morphology. Actin was concentrated at the tips of growing rhizoids. Actin cables typically formed cortical, parallel arrays in hyphae, but in mature sporangia they were concentrated in a funnel-shaped array in the central region. Thalli treated with latrunculin B had shorter rhizoids with fewer branches than controls. In both hyphae and monocentric thalli, actin localization coincides with active, polarized growth and cytokinesis. Specific actin localization patterns are largely shared between monocentric species but differ significantly from patterns observed in hyphae. Actin integrity is critical for sustaining filamentous growth in all fungi. [ABSTRACT FROM AUTHOR]

Ulva is recognized as a cosmopolitan genus in the order Ulvales of Chlorophyta. Here, we describe a new species of free-living uniseriate Ulva from the eastern coast of the Indian subcontinent. Distinguishing morphological characteristics include unbranched compressed filamentous thalli, tufts of thallus attached via rhizoids, quadrilateral to elongated cells with round apices, and parietal chloroplasts with multiple pyrenoids per cell. Phylogenetic reconstruction using nrDNA ITS1 locus revealed a distinct monophyletic clade encompassing all of our uniseriate accessions, thus corroborating the new species proposition under the framework of phylogenetic species concept. The closest BLASTn hit was found to be Ulva prolifera, but our isolates had synapomorphic trait of compressed uniseriate thalli which is absent in Ulva prolifera or any of the previously described species of Ulva to date. Based on morphological and molecular synapomorphy, a new free-living uniseriate species Ulva uniseriata sp. nov. is formally proposed. [ABSTRACT FROM AUTHOR]

Background and Aims Through careful field examination of the growth habit of the gametophytes and sporophytes of Hymenasplenium volubile across an ontogenetic series, we aim to understand better the evolution of epiphytism in this poorly understood group of ferns Methods We made field observations of H. volubile sporophytes and gametophytes, and brought specimens back to the lab for microscopic analysis. In the field, sporophytes at each ontogenetic stage were photographed to document the species' growth habit. We used an existing phylogeny to optimize growth form of New World Hymenasplenium. Key Results Young sporophytes were at first fully epiphytic and produced one or two long feeding roots that extend to the soil where they branch profusely. The feeding roots remain in contact with the soil throughout the life of the plant. Thus, H. volubile is a hemiepiphyte. While immature, gametophytes are appressed to the tree trunk, but, as their gametangia mature, their lower margin lifts upward, imparting a shelf-like appearance to the thallus. The thallus attaches to the substrate by branched rhizoids produced along the margin of the thallus in contact with the substrate. Conclusions Hemiepiphytes are a key link in the evolution of epiphytic ferns and may act as a bridge between the forest floor and the canopy. Our finding is the first report of hemiepiphytism in Aspleniaceae, a large lineage with many epiphytic and terrestrial taxa. This work serves as an important model to understand the evolution of epiphytism in this group specifically and in ferns in general. The majority of our understanding of fern gametophyte biology is derived from laboratory studies. Our efforts represent a fundamental contribution to understanding fern gametophyte ecology in a field setting. [ABSTRACT FROM AUTHOR]

Palaeonitella cranii is a charophyte alga (Charophyceae) from the Lower Devonian Rhynie chert of Scotland that consists of an axis of alternating internodes and nodes, with whorls of branchlets arising from the nodes. Conspicuous spherical to ovoid structures believed by most to be the bulbils of P. cranii are often found together with the axes and branchlets; however, they have so far only been insufficiently studied. Here, we revisit the bulbils, along with the rhizoids on which they were formed, based on new material from the Rhynie and Windyfield chert sites. The bulbils are up to 540 μm in diameter and occur singly or in groups on rhizoid nodes. A small node recognizable at the apical end in some specimens is evidence that the bulbils are modified branch rhizoids. There is also evidence of lower-order branch rhizoids extending from the apical node, as well as for sprouting. Palaeonitella cranii thrived in shallow pools and outflow channels of the Rhynie geothermal wetland. The bulbils might have enabled the plant to persist if photosynthesis was limited and to regenerate if the thallus was destroyed, but they might also have served as dispersal units. Other significantly inflated cells, which are not bulbils, may occur in both axes and branchlets of P. cranii , but are generally rare. Some of these cell alterations may be due to parasites. This study complements our understanding of P. cranii , the only fossil charophyte known from both above- and below-ground parts of the thallus, and from reproductive structures. • Palaeonitella cranii is the only charophyte described to date from the Rhynie chert. • Known from above- and below-ground thallus parts and reproductive structures. • Rhizoid nodes were formed in essentially the same way as in present-day charophytes. • Bulbils are branch rhizoids comprised of one inflated cell, with nodes at both ends. • P. cranii is a whole plant taxon, remarkably similar to present-day charophytes. [ABSTRACT FROM AUTHOR]

A new species, Saksenaea dorisiae (Mucoromycotina, Mucorales), isolated from a water sample originating from a private well in Manastirica, Petrovac, in the Republic of Serbia (Europe), is described and illustrated. The new taxon is well supported by multilocus phylogenetic analysis that included the internal transcribed spacer (ITS) region, domains D1 and D2 of the 28S rRNA gene (LSU), and translation elongation factor-1α gene (tef-1α), and it is resolved in a clade with S. oblongispora and S. trapezispora. This fungus is characterized by its moderately slow growth at 15 and 37°C, sparse rhizoids, conical-shaped sporangia, and short-cylindrical sporangiospores. Saksenaea dorisiae is a member of the opportunistic pathogenic genus often involved in severe human and animal mucormycoses encountered in tropical and subtropical regions. Despite its sensitivity to several conventional antifungals (terbinafine and ciclopirox), the fungus can potentially evoke clinically challenging infections. This is the first novel taxon of the genus Saksenaea described from the moderately continental climate area of Europe. [ABSTRACT FROM AUTHOR]

We investigated the effects of activated charcoal (AC), culture medium strength and various levels of thidiazuron (TDZ) on asymbiotic in vitro seed germination and seedlings development of Pecteilis radiata , an endangered terrestrial orchid. Seeds were inoculated in culture bottle containing quarter-, half- and full-strength Murashige and Skoog (1962) medium (MS) with 0, 1, 2, 4 or 8 μM thidiazuron (TDZ), 3% (w / v) sucrose, and 0.8% (w / v) plant agar. The culture medium strength, TDZ levels, and their interactions had a significant (P <.0001) effect on asymbiotic seed germination. Seeds cultured on full-strength MS medium containing 2 μM TDZ had the highest frequency of asymbiotic seed germination (90.2%) as compared with half-strength MS plus 2 μM TDZ (59.3%) and quarter-strength MS plus 2 μM TDZ (46.8%). The protocorms with rhizoids were subcultured on MS medium containing 0, 1, 2, 3, or 4 g L−1 activated charcoal (AC) for conversion of seedlings. The highest frequency of seedling conversion (91.7%) was obtained on MS medium containing 2 g L−1AC. The in vitro raised seedlings were acclimatized in the greenhouse with an 82% survival rate. The methanolic protocorm extract contained higher amounts of phenolics and flavonoids than shoot and tuber extracts. The methanolic protocorm extract of P. radiata also exhibited strong antioxidant activity. • An efficient protocol for asymbiotic in vitro seed germination of P. radiata has been established. • High frequency of asymbiotic seed germination in vitro was achieved on MS basal medium devoid of natural additives. • The addition of TDZ in the growth medium enhanced the frequency of asymbiotic seed germination. • The inclusion of AC in the growth medium reduced the protocorm browning. • The methanolic protocorm extract of P. radiata exhibited strong antioxidant activity. [ABSTRACT FROM AUTHOR]

Premise of research. Microbial mats in the Lower Devonian Windyfield chert comprise diverse communities of organisms; however, little information on the various life forms that occur in these formations is available. A recently cut and thin-sectioned block of Windyfield chert contains an extensive microbial mat that formed among an in situ stand of charophytes. Methodology. Thin sections of the chert were screened systematically at high magnification (×400 and ×1000) in transmitted light. Images of fossils were captured digitally and processed in Adobe Photoshop CS6. Pivotal results. The microbial mat contains 15 specimens of Nimbosphaera rothwellii nov. gen. et sp., a hitherto unknown microfossil composed of a vesicle containing spheroidal bodies and enveloped in a prominent sheath. Extending from some vesicles are a bulbous appendage and putative rhizoids. The fossils resemble the sheathed zoosporangia of certain extant chytrids, in particular Rhizophydium coronum , thus suggesting affinities of N. rothwellii to Chytridiomycota. Conclusions. This discovery expands our knowledge of the diversity of organisms that thrived in early nonmarine microbial mats and provides further evidence that microbial mat frameworks served as a conservation trap for delicate microbial life in the Rhynie and Windyfield settings. [ABSTRACT FROM AUTHOR]

Introduction. Heterophyllium albicans Thér., H. henryi Tixier, H. micro-alare (Broth. & Paris) Broth. and H. tonkinense (Broth. & Paris) Broth. were all either poorly known species or known only from the type collections since their inception. Methods. Examination of the type material confirmed that the alar cell structure in these species do not conform to the generic concept of Heterophyllium (Schimp.) Kindb. The study also revealed some new features previously unreported in these species, i.e., the filamentous pseudoparaphyllia, one of the characteristic features of the genus Isopterygium Mitt. Key Results & Conclusions. Three new combinations, Isopterygium albicans (Thér.) Y.Jia & S.He, I. micro-alare (Broth. & Paris) Y.Jia & S.He, and I. tonkinense (Broth. & Paris) Y.Jia & S.He are proposed. Heterophyllium henryi Tixier is treated as a new synonym of Brotherella henonii (Duby) M.Fleisch. [ABSTRACT FROM AUTHOR]