Thallus Margin Research Articles

Towards a nomenclatural clarification of the Peltigera ponojensis/monticola clade including metagenomic sequencing of type material and the introduction of P. globulata Miadl. & Magain sp. nov.

AbstractPeltigera globulata Miadl. & Magain, a new species in the P. ponojensis/monticola species complex of section Peltigera, is formally described. This clade was previously given the interim designation Peltigera sp. 17. It is found in sun-exposed and xeric habitats at high altitudes in Peru and Ecuador. Peltigera globulata can be easily recognized by its irregularly globulated margins covered mostly by thick, white pruina, somewhat resembling the sorediate thallus margins of P. soredians, another South American species from section Peltigera. The hypervariable region of ITS1 (ITS1-HR), which is in general highly variable among species of section Peltigera, does not have diagnostic value for species identification within the P. ponojensis/monticola complex. Nevertheless, no significant level of gene flow was detected among eight lineages representing a clade of putative species (including P. globulata) within this complex. ITS sequences from the holotype specimens of P. monticola Vitik. (collected in 1979) and P. soredians Vitik. (collected in 1981) and lectotype specimens of P. antarctica C. W. Dodge (collected in 1941) and P. aubertii C. W. Dodge (collected in 1952) were successfully obtained through Sanger and Illumina metagenomic sequencing. BLAST results of these sequences revealed that the type specimen of P. monticola falls within the P. monticola/ponojensis 7 clade, which represents P. monticola s. str., and confirmed that the type specimen of P. aubertii falls within a clade identified previously as P. aubertii based on morphology. The ITS sequence from the type specimen of P. soredians, which superficially resembles P. globulata, confirms its placement in the P. rufescens clade. Finally, we discovered that the name P. antarctica was erroneously applied to a lineage in the P. ponojensis/monticola clade. The ITS sequence from the type specimen of P. antarctica represents a lineage within the P. rufescens clade, which is sister to the P. ponojensis/monticola clade.

Ethyl methanesulfonate mutant library construction in Neopyropia yezoensis to provide germplasm resources for next-generation genome-selection breeding

With the development of the laver industry, germplasm depression has become a serious issue, and current cultivars cannot adapt to different aquaculture regions. In order to increasing the genetic diversity and developing more germplasm sources, it is urgent and reasonable to construct a mutant library with more new germplasms. In this research, a mutant library was constructed by ethyl methanesulfonate (EMS)-mutagenized archeospores, and the most optimal treatment procedure was determined by performing different mutagen concentrations (2.25%) and treatment times (30 min). A total of 1860 haploid thalli were produced as the M1 mutant population and further cultured into conchocelis clones for the reservation of germplasm resources. Among these, 667 individual thalli were evaluated for their phenotypic traits, including thallus length, thallus width, length/width, thallus shape, photosynthesis ability, thallus color, thallus margin, and specific growth speed. The mutation frequency of the length/width ratio was 17.39%, Fv/Fm and NPQ were 21.84% and 29.35%, respectively, and SGR was 13.59%. The mutation frequency of thallus color was 0.91%. This work may not only provide a basic practical reference guide for EMS-based mutant library construction for other seaweeds but, more importantly, also serve as a valuable resource for functional genomics research and laver breeding.

Two noteworthy ramicolous liverworts from Mount Roraima, Guyana: Frullania trigona and Metzgeria deniseana sp. nov.

Mount Roraima, at the geographical tripoint of Brazil, Guyana and Venezuela, is famous for its richness in rare and endemic species. Here we report two unusual ramicolous liverwort species from the north ridge of the mountain, located within the borders of the country of Guyana: Frullania (sect. Microphyllae) trigona and Metzgeria deniseana sp. nov. Frullania section Microphyllae is a group of ten species within subgenus Frullania, distributed in eastern Asia, Europe and tropical America, and characterized by the small dioicous plants with ocelli, caducous leaf lobes and tiny underleaves. Frullania trigona is one of the rarest species of the section and was only known from the type collection from Guadeloupe. It is recognized by the obclavate lobules with a very small mouth, leaf margins with protruding whitish trigones and the presence of a huge attachment cell at the dorsal leaf bases. The latter two features are unusual in Frullania and are unique to F. trigona. Metzgeria deniseana is a new member of the genus Metzgeria with saccate thallus lobes (= former genus Austrometzgeria) and stands out by the very irregular shaped sacs, varying from subglobose to strongly elongate, thallus margins with a wide and ill-defined border, and strongly convex gemmae with revolute margins. The discovery of Frullania trigona and Metgeria deniseana adds two further noteworthy species to the rich liverwort flora of Mount Roraima.

Apparent electron transport rate – a non-invasive proxy of photosynthetic CO2 uptake in lichens

During desiccation, both apparent electron transport rate (ETRapp) and photosynthetic CO2 uptake peak when external water has evaporated. External water, causing suprasaturation, weakens the strong correlation between ETRapp and CO2 uptake. Lichens are poikilohydric organisms passively regulated by ambient conditions. In theory, apparent electron transport rate (ETRapp), estimated by photosystem II yield measured in light (ΦPSII), is a proxy of photosynthetic CO2 uptake. Hydration level, however, is a complicating factor, particularly during suprasaturation that strongly reduces CO2 diffusion. Here, the cephalolichen Lobaria pulmonaria and two chlorolichens Parmelia sulcata and Xanthoria aureola were excessively hydrated before photosynthetic CO2 uptake and ΦPSII using imaging fluorescence tools were simultaneously measured while drying at 200µmol photons m-2s-1. CO2 uptake peaked when hydration had declined to a level equivalent to their respective internal water holding capacity (WHCinternal) i.e., the water per thallus area after blotting external water. CO2 uptake and ETRapp in all species were highly correlated at hydration levels below WHCinternal, but weaker at higher hydration (chlorolichens) or absent (cephalolichen). Yet, at a specimen level for the two chlorolichens, the correlation was strong during suprasaturation. The CO2 uptake-ETRapp relationship did not differ between measured species, but may vary between other lichens because the slope depends on cortical transmittance and fraction of electrons not used for CO2 uptake. For new lichen species, calibration of ETRapp against CO2 uptake is therefore necessary. At intrathalline scales, ΦPSII during drying initially increased along thallus margins before reaching maximum values in central portions when hydration approached WHCinternal. WHCinternal represents the optimal hydration level for lichen photosynthesis. In conclusion, ETRapp is an easily measured and reliable proxy of CO2 uptake in thalli without external water but overestimates photosynthesis during suprasaturation.

Two New Species of Placolecis (Lichenized Ascomycota) from China

Two new species of the lichen genus Placolecis are discovered in China, namely P. kunmingensis An. C. Yin & Li S. Wang and P. sublaevis An. C. Yin & Li S. Wang. The new combination P. loekoesiana (S.Y. Kondr., Farkas, J.J. Woo & Hur) An. C. Yin is proposed. Placolecis kunmingensis is characterized by having simple, spherical or ellipsoid, hyaline spores, and pear-shaped pycnidia; while P. sublaevis can be distinguished by its thallus forming larger aggregations with slightly flattened lobes at the thallus margin, and urn-shaped pycnidia. Descriptions, a phylogenetic tree and a key are provided for all the known Placolecis species in China.

<i>Monostroma alittorale</i>, a marine green algal species newly recorded in Korea

A marine green algal species (Chlorophyta) was collected from the eastern coast of Korea. It is morphologically characterized by monostromatic thallus, usually undulate and entire margins, cap-like chloroplast and several pyrenoids per cell. In a phylogenetic tree based on molecular data, the Korean alga nests in the same clade as Monostroma alittorale originally described from Japan, as a sister clade of M. grevillei from France. The genetic distance for ITS (Internal Transcribed Spacer) sequences among Monostroma species ranges from 2.3% to 38.2%. The value between the Korean entity and M. alittorale was calculated as 0.01%, considered to be intraspecific divergence. This Korean entity is identified as Monostroma alittorale based on morphological and molecular analyses. This is the first record of M. alittorale in Korea.

Cytokinin signaling coordinates development of diverse organs in Marchantia polymorpha

ABSTRACTCytokinins play an essential role in plant growth and development. A recent study showed that the cytokinin signaling pathway was conserved in the liverwort Marchantia polymorpha, and that it controlled gemma cup and rhizoid formation during thallus development. Here we show that the type-B response regulator, MpRRB, is mainly localized in the nucleus. Moreover, observations of thalli revealed that the distribution of air pores and the shape of the thallus margin are impaired in cytokinin-deficient lines and those defective in cytokinin signaling. This suggests that cytokinins regulate cell division and/or differentiation of precursor cells derived from the apical cell, thereby coordinating development of various organs produced on the thallus.

Studies on the Morphology and In Vitro Seed Germination of Polypleurum stylosum var. laciniata (Podostemaceae)

Polypleurum stylosum var. laciniata of the family Podostemaceae, is an endemic aquatic angiosperm, which grows on rocks in fast flowing rivers and streams in Kerala (India). The plant body is thalloid and it lacks the conventional differentiation into root and shoot and is attached to the rocks with the help of rhizoids. Vegetative growth occurs in submerged conditions and lowering of water table triggers flowering. Flower buds appear along the thallus margin enclosed by a spathella and sustained by two or three pairs of bracts. The ovary lacks a distinct style and the stigma is characteristically bifid. There are two stamens with their filaments fused, which keep on elongating and mingle with the stigma at maturity. High pollen–ovule and ovule–seed ratio indicate the high probability of plant establishment. Nearly 205 minute seeds are produced in a fruit. The embryo lacks plumule and radicle. In tissue culture, the seeds germinate and produce a green radical which sticks to the hard substratum by means of the epidermal outgrowths. The main thalloid plant body originates from the hypocotyl region as a bulge and grows into a prostrate branched thallus.

Microsensor studies on Padina from a natural CO2 seep: implications of morphology on acclimation to low pH.

Low seawater pH can be harmful to many calcifying marine organisms, but the calcifying macroalgae Padina spp. flourish at natural submarine carbon dioxide seeps where seawater pH is low. We show that the microenvironment created by the rolled thallus margin of Padina australis facilitates supersaturation of CaCO3 and calcifi-cation via photosynthesis-induced elevated pH. Using microsensors to investigate oxygen and pH dynamics in the microenvironment of P.australis at a shallow CO2 seep, we found that, under saturating light, the pH inside the microenvironment (pHME ) was higher than the external seawater (pHSW ) at all pHSW levels investigated, and the difference (i.e., pHME - pHSW ) increased with decreasing pHSW (0.9 units at pHSW 7.0). Gross photosynthesis (Pg ) inside the microenvironment increased with decreasing pHSW , but algae from the control site reached a threshold at pH 6.5. Seep algae showed no pH threshold with respect to Pg within the pHSW range investigated. The external carbonic anhydrase (CA) inhibitor, acetazolamide, strongly inhibited Pg of P.australis at pHSW 8.2, but the effect was diminished under low pHSW (6.4-7.5), suggesting a greater dependence on membrane-bound CA for the dehydration of HCO3 (-) ions during dissolved inorganic carbon uptake at the higher pHSW . In comparison, a calcifying green alga, Halimeda cuneata f. digitata, was not inhibited by AZ, suggesting efficient bicarbonate transport. The ability of P.australis to elevate pHME at the site of calcification and its strong dependence on CA may explain why it can thrive at low pHSW .

Pallaviciniites oishii(comb. nov.), a thalloid liverwort from the Late Triassic of Japan

Abstract The fossil liverwort Hepaticites oishii from the Momonoki Formation in Western Honshu, Japan is critically reviewed. The type material exhibits the following characteristics: (1) small thalloid plants with well-defined midrib and lamina; (2) regularly dichotomously branching habit; (3) attenuate apical part of thallus with unnotched apex; (4) lack of ventral scales; (5) undulate lamina and margin of thallus without marginal teeth or hair; and (6) presence of rhizoids on midrib. These characters suggest an affinity of H. oishii to members of simple thalloid liverworts, particularly Pallaviciniales (Jungermanniopsida, Marchantiophyta). The species is therefore assigned to the fossil genus Pallaviciniites with a new combination: Pallaviciniites oishii (Huzioka & Takahasi) T. Katag. This liverwort fossil is significant because it constitutes the first fossil record of the order Pallaviciniales from the Late Triassic of Eurasia and is the second-oldest fossil liverwort in East Asia after Riccardiothal...

New distributional record for Pyropia koreana: confirmed to occur on the South Island, New Zealand

Hwang & Lee (Bangiales, Rhodophyta), distinguished on the basis of habitat, colour, shape, thal-lus margins and arrangement of reproductive cells. In Korea, this species is known from the eastern coast, with specimens collected in an estuarine area growing in the shallow subtidal zone (Hwang and Lee 1994, 2001, Kim and Kim 2011). As part of a major revision of the order Bangiales, Sutherland et al. (2011) transferred this spe-cies to the genus

Reappraisal of Dendroceros cucullatus (Dendrocerotaceae, Anthocerotophyta)

Dendroceros is an epiphytic or epiphyllous genus within Anthocerotophyta, with about 48 extremely specialised species in having endosporic germination (Villarreal et al. 2010; Garcia et al. 2012). Dendroceros difficilis was originally described by Stephani (1917: 1009), based on a collection made by V. Schiffner from Java, Indonesia. Hasegawa (1980) reduced a little-known species D. cucullatus Stephani (1923: 429) from the Philippines, to its synonym. An examination of the holotypes of both species, however, reveals that D. cucullatus is quite different from D. difficilis in thallus margin, structure of costa and epidermal cells of capsule. Dendroceros cucullatus is thus reinstated as a separate species. Based on Schuster’s (1987) treatment, these two species belong to subgenus Apoceros Schuster (1987: 195) based on the cavernous costa in both. Dendroceros difficilis has been described and illustrated by Hasegawa (1980) and Piippo (1993). The following description of D. cucullatus is based on the holotype kept in Geneva Herbarium (G) and recently collections from Thailand.

Caloplaca anularisandCaloplaca scrobiculataare Distinct

VONDRÁK, J. & MAYRHOFER, H. 2013. Caloplaca anularis and Caloplaca scrobiculata are distinct.— Herzogia 26: 21–29.Caloplaca anularis, described from the Western Alps, and Caloplaca scrobiculata, described from Central Asia, are distinct species. The main differences are the shape of the thallus margin, the anatomy of the thalline cortex, characters of the algal layer and the ascospores. Caloplaca anularis is a widespread lichen known from mountain ranges in Europe (Alps, Carpathians, Balkan Peninsula), Near Asia (continental Turkey and Caucasus) and Central Asia (Altay, Karakorum, Hengduan Shan). The specimens from Central Asia differ slightly from the European specimens in thallus and medulla thickness, but we consider this difference environmentally induced and taxonomically insignificant. Caloplaca scrobiculata is restricted to arid mountain ranges of Central Asia. The Central Asian Caloplaca bohlinii does not differ significantly from C. anularis. The new combination Caloplaca anularis f. ignea is made for specimens of C. anularis with a red thallus.

Gene expression indicates a zone of heterocyst differentiation within the thallus of the cyanolichen Pseudocyphellaria crocata

Development of the symbiotic association in the bipartite lichen Pseudocyphellaria crocata was investigated by characterizing two regions of the thallus. Thallus organization was examined using microscopy. A HIP1-based differential display technique was modified for use on Nostoc strains, including lichenized strains. Northern hybridization and quantitative real-time polymerase chain reaction were used to confirm differential display results, and determine expression levels of key cyanobacterial genes. Photosystem II yield across the thallus was measured using pulse-amplitude modulated fluorescence. Microscopy revealed structural differences in the thallus margins compared with the centre and identified putative heterocysts in both regions. Differential display identified altered transcript levels in both Nostoc punctiforme and a lichenized Nostoc strain. Transcript abundance of cox2, atpA, and ribA was increased in the thallus margin compared with the centre. Expression of cox2 is heterocyst specific and expression of other heterocyst-specific genes (hetR and nifK) was elevated in the margin, whereas, expression of psbB and PSII yield were not. Structural organization of the thallus margin differed from the centre. Both regions contained putative heterocysts but gene expression data indicated increased heterocyst differentiation in the margins where photosystem II yield was decreased. This is consistent with a zone of heterocyst differentiation within the thallus margin.

Primary hemiepiphytism and gametophyte morphology in Elaphoglossum amygdalifolium (Dryopteridaceae)

Elaphoglossum amygdalifolium holds a critical phylogenetic position as sister to the remaining ca. 600 extant species of Elaphoglossum and may provide important insight into the evolution of epiphytism in this clade of ferns. Here, we present the first examination of growth habit and gametophyte morphology for this species. We show that the cordate to elongate-cordate gametophytes occur up to 0.5 m above the ground on the base of tree trunks. Unlike the gametophytes of all other studied species of Elaphoglossum, rhizoids are absent along the thallus margin and the hairs present on the margin lack whitish waxy caps; both differences are pleisiomorphic for the genus. Sporelings of E. amygdalifolium produce a single long root that grows straight into the soil where it branches profusely. Mature sporophytes have long-creeping rhizomes that climb to heights of at least 3 m and produce two types of roots: “feeding roots” that reach the ground and “clasping roots” that anchor the sporophyte to its host plant. Our observations reveal that E. amygdalifolium is a primary hemiepiphyte, the first example of this growth habit to be documented in Elaphoglossum. Results of an ancestral state reconstruction of growth habit in bolbitidoid ferns show that both primary hemiepiphytism and holoepiphytism are equally likely to be the ancestral character state for Elaphoglossum.

An Early Carboniferous leaf-colonizing fungus

Documented evidence of fungi inhabiting the leaves of Palaeozoic land plants is rare. This paper describes impressions of rosette-like fungal thalli on a dispersed plant cuticle from the Lower Carboniferous of Chemnitz-Glosa (Germany). Circular structures in the centre of one thallus are interpreted as infection pores. Host reactions occur in the form of extensive cutinizations around the thallus margins. The thalli are interpreted as hyphopodia or some other epiphyllous structure of a parasitic fungus that facilitated host attachment and penetration. This discovery represents the oldest direct fossil evidence of fungal growth on leaf surfaces.

New insights in the evolution of the liverwort family Aneuraceae (Metzgeriales, Marchantiophyta), with emphasis on the genus Lobatiriccardia

AbstractPhylogenetic analyses using two fast evolving plastid markers (rps4, trnL‐F) reveal the occurrence of the Australasiatic liverwort genus Lobatiriccardia in the Neotropics. Two new species, Lobatiriccardia oberwinkleri and L. verdoornioides are reported from Ecuador. Phylogenetic reconstructions support Lobatiriccardia and Aneura as monophyletic sister groups and do not place Verdoornia as the first branching Aneuracean taxon but rather sister to Aneura and Lobatiriccardia, which is consistent with mycothallus development in Aneuraceae. Subsequently, Aneuraceae, as treated here, include Aneura, Lobati‐ riccardia, Riccardia, and Verdoornia. Although high levels of genetic structure can be observed among members of the Aneura pinguis complex, current species delimitations are questionable, and detailed analyses of cryptic speciation and biogeographic patterns are needed to understand the evolution of Aneura, with particular attention paid to the non‐photosynthetic species Aneura mirabilis. Ancestral state reconstructions suggest an evolutionary trend of female gametangia, and subsequently the sporophyte, moving from a central position on the dorsal side of the thallus (Verdoornia) to a marginal position between thallus lobes (Lobatiriccardia) to a more ventral (quasi latero‐ventral) position under the thallus margin (Aneura).

Growth of crustose lichens: a review

.Crustose species are the slowest growing of all lichens. Their slow growth and longevity, especially of the yellow‐green Rhizocarpon group, has made them important for surface‐exposure dating (lichenometry). This review considers various aspects of the growth of crustose lichens revealed by direct measurement including: 1) early growth and development; 2) radial growth rates (RGR, mm yr−1); 3) the growth rate–size curve; and 4) the influence of environmental factors. Many crustose species comprise discrete areolae that contain the algal partner growing on the surface of a non‐lichenized fungal hypothallus. Recent data suggest that ‘primary’ areolae may develop from free‐living algal cells on the substratum while ‘secondary’ areolae develop from zoospores produced within the thallus. In more extreme environments, the RGR of crustose species may be exceptionally slow but considerably faster rates of growth have been recorded under more favourable conditions. The growth curves of crustose lichens with a marginal hypothallus may differ from the ‘asymptotic’ type of curve recorded in foliose and placodioid species; the latter are characterized by a phase of increasing RGR to a maximum and may be followed by a phase of decreasing growth. The decline in RGR in larger thalli may be attributable to a reduction in the efficiency of translocation of carbohydrate to the thallus margin or to an increased allocation of carbon to support mature ‘reproductive’ areolae. Crustose species have a low RGR accompanied by a low demand for nutrients and an increased allocation of carbon for stress resistance; therefore enabling colonization of more extreme environments.

CHARACTERIZATION OF MARTENSIA (DELESSERIACEAE, RHODOPHYTA) BASED ON A MORPHOLOGICAL AND MOLECULAR STUDY OF THE TYPE SPECIES, M. ELEGANS, AND M. NATALENSIS SP. NOV. FROM SOUTH AFRICA(1).

An examination of a series of collections from the coast of Natal, South Africa, has revealed the presence of two species of Martensia C. Hering nom. cons: M.elegans C. Hering 1841, the type species, and an undescribed species, M.natalensis sp. nov. The two are similar in gross morphology, with both having the network arranged in a single band, and with reproductive thalli of M.elegans usually larger and more robust than those of M.natalensis. Molecular studies based on rbcL sequence analyses place the two in separate, strongly supported clades. The first assemblage occurs primarily in the Indo-West Pacific Ocean, and the second is widely distributed in tropical and warm-temperate waters. Criteria that have been used in the past for separating the two, namely, the number and shape of the blades, the presence of a single- versus a multiple-banded network, and blade margins entire or toothed, were determined to be unreliable. Although the examination of additional species is required, the morphology and position of procarps and cystocarps, whether at or near the corners of the longitudinal lamellae and the cross-connecting strands or along the lobed, membranous edges of the longitudinal lamellae or on the thallus margins, may prove to be diagnostic at the subgenus level. We recognize subg. Martensia, including the type of Martensia: M.elegans and subg. Mesotrema (J. Agardh) De Toni based on Martensia pavonia (J. Agardh) J. Agardh.

Intrathalline Variation of Chlorophyll a Fluorescence Emission in The Epiphytic Lichen Flavoparmelia Caperata

Abstract The intrathalline heterogeneity of chlorophyll a fluorescence (CaF) in thalli of the foliose lichen Flavoparmelia caperata was studied measuring Fo, Fm, Fv/Fm, ΔF/Fm′, NPQ and Ft in two spots of 25 mm2 positioned at ca 0.8 and 3 cm from the thallus margin. Measurements were carried out both in the field and in the laboratory using north-exposed, epiphytic thalli occurring in a deciduous wood of the Karst plateau (Trieste, NE Italy). With the exception of NPQ, all parameters were statistically higher in the marginal spots than in the central ones, suggesting that the level of photochemical activity is higher where the photobiont cells are more dense and younger. Fm and Fv/Fm of marginal spots measured in the field were statistically lower than those measured in the laboratory, probably as a consequence of the different pre-treatment conditions. The importance of selecting a specific measuring spot, particularly for biomonitoring purposes, is discussed.