Nitella Research Articles

Taxonomy, morphology and phylogenetic placement of a new species Nitella pluripapillifera sp. nov. (Charales, Charophyta) from Japan

ABSTRACT We examined the morphology and taxonomy of specimens of the genus Nitella, collected from the main island of Okinawa, Japan. Based on their vegetative and reproductive characteristics, the samples were most similar to Nitella tumulosa, as the two species have a large monoicous thallus without mucus, an abbreviated two-celled dactyl and papillate oospore walls. Nevertheless, the two species can be differentiated based on variations in the overall appearance of thalli and the size of oogonia. Moreover, scanning electron microscopy observations revealed the detailed structures of oospores of specimens collected from Okinawa, and their oospore characteristics were clearly distinguishable from those of N. tumulosa and other related taxa. Additionally, molecular phylogenetic analyses demonstrated that the specimens collected from the main island of Okinawa were phylogenetically separated from a clade comprising specimens of N. tumulosa. Therefore, we propose a new species from the specimen collected from the main island of Okinawa as, Nitella pluripapillifera sp. nov.

Actual diversity and distribution of charal algae of the genus <i>Nitella</i> C.Agardh (Charophyta) in Ukraine)

The results of the analysis of literature and original data on the species diversity and distribution patterns of algae of the genus Nitella C.Agardh (Charophyta, Charales) in Ukraine are presented. Now, the diversity of the genus Nitella in Ukraine is represented by 9 species out of 13, known in the Europe flora of Charales, namely: Nitella capillaris (Krock.) J.Groves et Bull.-Webst., N. confervacea (Bréb.) A.Braun ex Leonh., N. gracilis (Sm.) C.Agardh, N. flexilis (L.) C.Agardh, N. mucronata (A.Braun) Miq., N. opaca (C.Agardh ex Bruz.) C.Agardh, N. syncarpa (Thuill.) Chev., N. tenuissima (Desv.) Kütz. and N. translucens (Persoon) C.Agardh. An annotated list of Ukrainian species in Ukraine. A total of 78 locations have been registered, including historical, lost, and modern ones. Most of them were found within the Pripyat-Desnianska (PpDSAP) (50) and Serednyodniprovska (SDpAP) (21), much less  within the Dnieper-Black Sea (DpAp) (3) and Carpathian-Danube (CpDnAP) (4) algofloristic subprovinces. It is suggested that main limiting factors influencing on diversity and distribution patterns of the Nitella species in Ukraine are the type of waterbodies, temperature, a degree of minimalization as well as chemical main ionic composition of water and active reaction (pH) of water.

Integrative Taxonomic, Ecological and Genotyping Study of Charophyte Populations from the Egyptian Western-Desert Oases and Sinai Peninsula.

Present-day information available on the charophyte macroalgae in Egypt, including their phylogenetic affinities, remains largely incomplete. In this study, nine charophyte populations were collected from different aquatic biotopes across the Egyptian Western-Desert Oases and Sinai Peninsula. All populations were investigated using an integrative polyphasic approach including phylogenetic analyses inferred from the chloroplast-encoded gene (rbcL) and the internal transcribed spacer (ITS1) regions, in parallel with morphotaxonomic assignment, ultrastructure of the oospore walls, and autecology. The specimens identified belonged to the genera Chara, Nitella, and Tolypella, with predominance of the first genus to which five species were assigned though they presented some interesting aberrant taxonomic features: C. aspera, C. contraria, C. globata, C. tomentosa, and C. vulgaris. Based on our integrative study, the globally rare species C. globata was reported for the second time for the whole African continent. The genus Nitella was only represented by N. flagellifera, and based on the available literature, it is a new record for North Africa. Noteworthy, an interesting Tolypella sp., morphologically very similar to T. glomerata, was collected and characterized and finally designated with the working name ‘Tolypella sp. PBA–1704 from a desert, freshwater wetland’, mainly based on its concatenated rbcL+ITS1 phylogenetic position. This study not only improved our understanding on the diversity, biogeography and autecological preferences of charophytes in Egypt, but it also broadened our knowledge on this vulnerable algal group in North Africa, emphasizing the need of more in-depth research work in the future, particularly in the less–impacted desert habitats.

<p><strong><em>Nitella singaporensis</em></strong><strong> (Charophyceae, Charales): new species and implications for the taxonomy of the genus <em>Nitella</em></strong></p>

Nitella singaporensis is described as a new species based on specimens from Singapore. This study provides detailed examination of the fully mature plant. The species is described here using multiple methods including scanning electron microscopy and molecular phylogenetics. Re-examination of the type specimen of N. caespitosa, the most similar species, will be necessary for future studies. The particular oospore surface pattern visible using scanning electron microscopy, which does not equate to previously described features, is recorded here for the first time in the genus Nitella. Nitella singaporensis is placed in section Gioallenia of subgenus Tieffallenia according to its morphological and phylogenetic affinities. The presence of adventitious cells at base of the branchlets and significance of this trait for Nitella taxonomy is discussed.

Environmental predictors of charophytes in a subtropical reservoir

Abstract: Aim In this study we check whether three simple environmental factors are good predictors of charophytes occurrence. Methods The Characeae material was sampled two times a year during the years of 2001, 2002 and 2003, over 235 sites distributed along eight rivers located in Itaipu, a large subtropical reservoir. While sampling the biological material, the measurement of environmental descriptors pointed out as the most important variables predicting the occurrence of submerged macrophytes were simultaneously taken. At each sampling site, using a four meter long pipe rake, the presence and absence of Charophytes were recorded, the biological material was sampled and fixed to posterior identification in laboratory following specialized literature, and measurements of the electrical conductivity, Secchi depth and the effective fetch were taken. Results A total of 13 species, belonging to the genus Chara and Nitella, were identified. An increase of the charophytes frequency towards the dam was found, which may reflects the gradient of sedimentation and reduction of the inputs of solids and nutrients, leading to a higher underwater transparency, a suitable condition to the development of submerged macrophytes. The genus Nitella occurred in all rivers and was more frequent than the genus Chara. Regarding the effect of electrical conductivity over the charophytes, the frequency of the genus Chara was found to be affected by this variable, while the effective fetch, variable that indicates wave disturbance, affected genus Nitella. Conclusions The water transparency, related with Secchi depth, was the best predictor for the charophytes occurrence, agreeing with the distribution pattern of other submerged macrophytes of this large subtropical Reservoir.

(2721) Proposal to conserve the name Chara flexilis (Nitella flexilis) (Characeae) with a conserved type

(2721) Proposal to conserve the name <i>Chara flexilis</i> (<scp><i>Nitella flexilis</i></scp>) (<i>Characeae</i>) with a conserved type

&lt;p&gt;&lt;strong&gt;Molecular taxonomic report of &lt;em&gt;Nitella megacephala sp. nov.&lt;/em&gt; (Characeae, Charophyceae) from Korea&lt;/strong&gt;&lt;/p&gt;

We report a new taxonomic entity of Nitella megacephala sp. nov. (Charales, Charophyceae) from Korea. The characean algae collected from two sites (Haenam-gun and Kangjin-gun) had distinctive morphological characteristics representing a new Nitella species. Those samples showed a light-green color in gross morphology and a plant body length up to 13 cm. Moreover, the two-celled dactyls and head formation differed clearly from closely related Nitella species (N. moriokae, N. spiciformis, and N. translucens). From a molecular phylogenetic analysis of rbcL DNA sequences, Nitella megacephala sp. nov formed a single clade with N. translucens, N. moriokae and N. spiciformis, and was distantly related to those three species as a sister taxon. In the terms of interspecific sequence variation, Nitella megacephala showed 3.2–5.5% pairwise distance values with sister groups in phylogenetic tree (N. translucens, N. moriokae and N. spiciformis) and 3.2–9.1% with other of Nitella species. In contrast, its sister group species differed 0.3–1.7% at the interspecific level. These unique morphological and molecular taxonomic characteristics clearly support the establishment of this taxonomic entity as a new species in the genus Nitella (Nitella megacephala sp. nov.)

Taxonomy and phylogeny of Nitella (Charophyceae, Characeae) from Brazil with emphasis on the midwest and southeast regions

The genus Nitella is the most species-rich within the Charales. Brazilian studies on the genus are relatively scarce and consist of floristic surveys, lacking modern and more precise information. This investigation applied scanning electron microscopy to analyze the oospore wall and molecular data associated with traditional morphological characters to analyze forty-two populations of Nitella from the midwest and southeast regions of Brazil. Forty-two new sequences of rbcL, twelve of ITS1 and twenty-three of ITS2 were generated for the five species recognized in this study: Nitella acuminata A. Braun ex Wallman, Nitella axillaris A. Braun, Nitella elegans B. P. Pal, Nitella flagellifera J. Groves &amp; G. O. Allen and Nitella microcarpa A. Braun.. Phylogenetic analyses of sequences of these three markers were congruent in that they grouped our species with others from different countries to form five clades. Our results on ultrastrucure of the oospore wall were consistent with previous studies for the same species from other regions of the world. The data reinforced the conclusion that the use of ornamentation of oospore wall may be extremely useful for the construction of a natural system for Characeae at section level. Molecular evidence, reinforced by morphological data, for the Brazilian material analyzed suggests that Nitella subglomerata A. Braun and Nitella gollmeriana A. Braun could be synonymys of Nitella acuminata; and Nitella axilliformis K. Imahori appears to be the same as Nitella axillaris. However, no formal proposition was made considering that type specimens were not analyzed and these observations were based on a relatively small number of samples strictly from Brazil. We showed that even among geographically distant populations, such as from other continents, of some Nitella species, the degree of identity among DNA sequences was high.

Biogeography of Chilean Charophytes – determined by climate or by water chemistry?

Distinct distribution patterns were observed for several species of charophytes during a survey in Chile. We attempted to link these patterns to climatic conditions, but no direct causality between specific climatic factors and charophyte growth conditions could be identified. In this paper, correlations between water chemistry and occurrence of charophytes were tested as an alternative approach to explain the distribution pattern. Datasets with information about conductivity, alkalinity, pH and concentrations of calcium, magnesium, sodium, potassium, sulphate and chloride from sites inhabited by at least one charophyte species were analysed by principal component analysis. The results show that the distribution patterns of at least some species can be explained by niche differences with respect to water chemistry. The genera Chara and Nitella are in general well separated by their preferences for a given pH, alkalinity and conductivity range. Within the genus Chara, Chara squamosa, Chara braunii, Chara fulgens, and a yet unidentified taxon Chara sp., differ from this genus-specific pattern with respect to at least one parameter, whereas Chara vulgaris occupies a broad niche, covering almost the full range of all parameters except conductivity. Within the genus Nitella, niche separation by water chemistry was only possible between Nitella tenuissima and Nitella asagrayana. The chemical niche of Chara braunii was more closely related to the niche of the genus Nitella than the niche of other Chara species.

Interacoes do ácido indolil-3-acético e calcio sobre o fluxo de água de células de Nitella

The effect of indol-3-acetic acid (lAA) and calcium (Ca + +) on the flow of water through Nitella celIs was studied. Nitella cernua Braun was selected because it is possible to study the permeability of a single isolated cell. IAA was used at a concentration of 0,28 10 -3 M and CaCI 2 at 10 -3 M. The effect of IAA on the isolated cells was confirmed by the increase of plasticity and permeability of the plasmalema of the treated cells with absorption and a consequent elimination of water. The effect was reversed by Ca ions.

Using morphology and genomic template stability (GTS) tracking herbicide effect on some submersed aquatic plants

The biodiversity are related to environmental status, the natural ponds contained more aquatic plant diversity than paddy field. Some species were found only in paddy fields e.g. Najas Graminea Del., while, some species were found only in natural water pond such as Ceratophyllum demersum Linn. Therefore these major species were selected for herbicide effect testing. The effect of glyphosate and butachlor on aquatic plant was observed in experiment, the color and morphology showed changing related to higher dose treatment. The RAPD profiles was analyzed for genomic template stability (GTS), the results indicated that GTS of Hydrilla verticellata was lowest (7.14%GTS), follow by Utricularia aurea lour (30.77 % GTS), Najas Graminea Del (38.71 %GTS), and Nitella sp. (59.38%GTS), respectively. The results indicated that these herbicides caused abnormally morphology and DNA instability, the RAPD profile cloud be used as biomarker for detection of herbicide contamination in aquatic ecological system.

Biodiversity Changes of Charophytes in Lakes and Ponds of the Duero Basin (NW-Spain) over a Twenty-year Period

With the main goal of investigate the charophyte diversity changes over a period of 20 years, an extensive survey of lakes and ponds of the Duero basin was conducted during the summer of 2005. The results were then compared with those obtained by Alonso & Comelles during a decade (1977-86). Out of the 39 visited water bodies that contained water in 2005, only 14 hosted 10 taxa of charophytes: 8 belonging to the genus Chara and 2 to the genus Nitella. Unlike previous studies, all the water bodies examined in 2005 were highly affected by anthropogenic disturbances. However, no significant differences between sites with or without charophytes were found for any of the studied ecological variables. This suggests that charophytes can adapt to a wide range of habitat conditions, and highlights the need to preserve and maintain the previous heterogeneous nature of the visited water bodies. Moreover, a reduction in charophyte species richness was noted over time. This may have been due to the increasing effect of anthropogenic disturbances, which were mostly related to agricultural and livestock farming activities and alter the water quality of the ecosystems as well as the charophyte flora they harbour.

Predicting aquatic macrophyte occurrence in soft-water oligotrophic lakes (Pyrenees mountain range)

Distribution of aquatic macrophytes in lakes is related to geographical, morphological, catchment and water chemistry variables as well as human impacts, which modify the original environment. Here, we aim at building statistical models to establish the ecological niches of 11 aquatic macrophytes (10 different phanerogams and the genus Nitella ) from oligotrophic soft-water lakes and infer their ecological requirements and environmental constraints at the southernmost limit of their distribution. Macrophyte occurrence and environmental variables were obtained from 86 non-exploited oligotrophic soft-water lakes from the Pyrenees (Southern Europe; 42o50´N, 1o00´E); macrophytes inhabited 55 of these lakes. Optimum ranges and macrophyte occurrence were predicted in relation to 18 geographical, morphological, catchment and water chemistry variables using univariate and multivariate logistic models. Lakes at low altitude, in vegetated catchments and with low water concentration of NO 3 - and SO 4 -2 , were the most suitable to host macrophytes. In general, individual species of aquatic macrophytes showed clear patterns of segregation along conductivity and pH gradients, although the specific combination of variables selected in the best models explaining their occurrence differed among species. Based on the species response to pH and conductivity, we found Isoetes lacustris have its optimum in waters with low conductivity and pH (i.e. negative monotonic response). In contrast, Callitriche palustris , Ranunculus aquatilis , Subularia aquatica , Nitella spp., and Myriophyllum alterniflorum showed an optimum at intermediate values ( i.e. unimodal response), whereas Potamogeton berchtoldii , Potamogeton alpinus , and Ranunculus trichophyllus as species had their optimum at relatively high water pH and conductivity (i.e. positive monotonic response). This pattern has been observed in other regions for the same species, although with different optima and tolerance ranges. The parsimonious models developed here allowed us to explore niche requirements for each species and to predict the occurrence of macrophytes and of individual species in any particular lake by using only few, easily measured environmental variables. This is of interest to forecast possible changes related to global change and to assist managers in making conservation, management and restoration decisions.

Aquatic macrophytes of Lake Rotopounamu, a montane volcanic lake in New Zealand

Abstract Lake Rotopounamu (710 m a.s.l.) is located in red beech/kamahi forest in Tongariro National Park in the central North Island of New Zealand. The maximum depth of the lake is 7.9 m, and it has neutral pH (7.1), soft water, and a predominantly silty substrate. It probably alternates between warm thereintictic and polymictic. No exotic, aquatic macrophytes are present. Beds of sedges (including Baumea rubiginosa (Spreng.) Boeck.) are patchy on the southern shores. Submerged communities have 2 zones: at 0.1–2.5 m deep a low growing, inshore community of Myriophyllum pedunculatum Hook.f., Lilaeopsis lacustris Hill, and Glossostigma elatinoides Benth. and at 2.5–7.9 m deep a characean algal community of Nitella pseudoflabellata (Nordst.) Bailey and N. leptostachys var. Leonhardii (R.D.W.) R.D.W. Three species of aquatic liverwort are also recorded. The absence of a tall macrophyte zone, found in many other New Zealand lakes, is discussed.

An overview of Nitella (Characeae, Charophyceae) in Australia

The genus Nitella Ag. in algal family Characeae is characterised by furcate (forked) branchlets, compressed oospores (i.e. oval in cross-section), terminal antheridia and a 10-celled coronula on the oogonium. Species of Nitella are submerged plants that grow in a variety of wetland and riverine habitats. Approximately 89 taxa of Nitella (species, subspecies, varieties and forms) have been described on the basis of Australian collections, and published estimates of the number of species range from 18 to &gt;35. The lower value is based on the assumption that infra-specific variation is great, species have a wide distribution, monoecy and dioecy are not indicative of speciation and the number of furcations and the ratio of branchlet segment lengths vary for a species owing to the environment in which they grow. The higher value is based on evidence that morphological characters are relatively constant for a species, that oospore variation is a good indication of speciation and that monoecious and dioecious entities are not inter-fertile. An overview of Australian members of the genus is presented here as a framework for further taxonomic work. Representatives of all three subgenera of Nitella occur in Australia, with subgenus Nitella poorly represented, and subgenera Tieffallenia and Hyella equally speciose. The subgenera are defined here in relation to the Australian taxa they contain. In the present treatment, section Migularia is transferred from subgenus Tieffallenia to subgenus Hyella, and several species are transferred to subgenus Tieffallenia. Within subgenus Tieffallenia, variation in vegetative and oospore morphology is useful for distinguishing among sections and species. However, although members of subgenus Hyella display a similar range of variation in vegetative morphology, most of the species have similar, reticulate, oospore ornamentation. Australia is home to a large number of endemic species of Nitella, many of which are dioecious. The total number of species and the degree of endemism have been underestimated in earlier studies, and it is likely that more than 50 species of Nitella will be recognised on the basis of Australian specimens. A key to the subgenera, and keys to sections in the subgenera are provided.

Review: Taxonomy of Nitella (Charales, Charophyceae) based on comparative morphology of oospores and multiple DNA marker phylogeny using cultured material

SUMMARYThe genus Nitella is the largest group in the Charales and has the highest diversity of vegetative and oospore morphologies. In his worldwide monograph on the Charales, R. D. Wood characterized the sections and species of Nitella mainly on the basis of vegetative morphology and treated oospore wall morphology as diagnostic at the infraspecific level. Therefore, many species of Nitella exhibiting distinct external morphology of the oospore wall (EMOW) were reduced to infraspecific rank and only 53 of 204 species previously described were recognized within Nitella. However, recent morphological and molecular phylogenetic studies have demonstrated the phylogenetic validity of using EMOW for diagnosing some species of Nitella. More recently, a scanning electron microscopy (SEM) study of internal morphology of the oospore wall (IMOW) and multiple DNA marker analyses using both nuclear and chloroplast gene sequences were conducted to improve our understanding of the taxonomy of Nitella at the species level, on the basis of cultured material of a large number of species. Multiple DNA marker analyses resolved detailed and robust phylogenetic relationships within the genus and demonstrated the taxonomic and phylogenetic significance of IMOW. In addition, they supported the taxonomic decisions based on differences in oospore morphology, suggesting that an integrated approach, involving both SEM studies of the EMOW and IMOW and multiple DNA marker analyses, is appropriate to address problems at lower taxonomic levels within the genus, as well as to construct a natural taxonomic system for the genus. In this paper, recent morphological and molecular phylogenetic studies are reviewed and recent improvements in taxonomy of Nitella are summarized. Moreover, the evolution of morphological features and phylogenetic relationships within Nitella are discussed, focusing especially on oospore morphology.

A fundamental plant evolutionary problem: the origin of land-plant sporophyte; is a new hypothesis possible?

The origin of the sporophyte in land plants represents a fundamental phase in the plant evolution. Today this subject is controversial and, in my opinion, scarcely considered in our textbooks and journals of botany, in spite of its importance. There are two conflicting theories concerning the origin of the alternating generations in land plants: the "antithetic" and the "homologous" theory. These have never been fully resolved. The antithetic theory maintains that the sporophyte and gametophyte generations are fundamentally dissimilar and that the sporophyte originated in an ancestor organism with haplontic cycle by the zygote dividing mitotically rather than meiotically, and with a developmental pattern not copying the developmental events of the gametophyte. The sporophyte generation was an innovation of critical significance for the land-plant evolution. By contrast, the homologous theory simply stated that a mass of cells forming mitotically from the zygote adopted the same developmental plan of the gametophyte, but giving origin to a diploid sporophyte. In this context, a very important question concerns the possible ancestor or ancestors of the land plants. Considerable evidences at morphological, cytological, ultrastructural, biochemical and, especially, molecular level, strongly suggest that the land plants or Embryophyta (both vascular and non-vascular) evolved from green algal ancestor(s), similar to those belonging to the genus Coleochaete, Chara and Nitella, living today. Their organism is haploid for most of their life cycle, and diploid only in the zygote phase (haplontic cycle). On the contrary, the land plants are characterized by a diplo-haplontic life cycle. Several questions are implied in these theories, and numerous problems remain to be solved, such as, for example, the morphological difference between gametophyte and sporophyte (heteromorphism, already present in the first land plants, the bryophytes), and the strong gap existing between these last with a sporophyte dependent on the gametophyte, and the pteridophytes having the gametophyte and sporophyte generations independent. On the ground of all of the evidences on the ancestors of the land plants, the antithetic theory is considered more plausible than the homologous theory. Unfortunately, no phylogenetic relationship exists between some green algae with diplontic life cycle and the land plants. Otherwise, perhaps, it should be possible to hypothesize another scenario in which to place the origin of the alternating generations of the land plants. In this case, could the gametophyte be formed by gametes produced from the sporophyte, through their mitoses or a delayed fertilization process?

Observations on the morphology and oospore wall ornamentation in culture of the rediscovered Japanese endemic Nitella gracilens (Charales, Chlorophyta)

The Japanese endemic charalean species Nitella gracilens Morioka (=N. furcata subsp. furcata var. sieberi f. gracilens) was thought to be extinct until it was rediscovered at the type locality, Lake Ashinoko, Kanagawa Prefecture. Uni-charalean cultures of N. gracilens were established and sexual organs developed and matured. The morphology of this alga, examined by light microscopy, corresponds closely with the original description by Morioka, particularly with regard to the oospores. The mature oospore walls of N. gracilens are orange or yellowish-brown and the fossa wall of the oospore is smooth or has a finely granulate ornamentation. In addition, scanning electronic microscopic examination demonstrated that the fossa walls have minute granulate structures that are compactly arranged. These observations contrast with a previous report that the oospore wall ornamentation of this taxon is reticulate. Since oospore wall ornamentation and the form of the dactyls in N. gracilens are essentially different from those of other infraspecific taxa of N. furcata sensu Wood (1965), N. gracilens should be maintained as a distinct morphological species within the genus Nitella.

Observations on the morphology and oospore wall ornamentation in culture of the rediscovered Japanese endemic Nitella gracilens (Charales, Chlorophyta)

The Japanese endemic charalean species Nitella gracilens Morioka (=N. furcata subsp. furcata var. sieberi f. gracilens) was thought to be extinct until it was rediscovered at the type locality, Lake Ashinoko, Kanagawa Prefecture. Uni-charalean cultures of N. gracilens were established and sexual organs developed and matured. The morphology of this alga, examined by light microscopy, corresponds closely with the original description by Morioka, particularly with regard to the oospores. The mature oospore walls of N. gracilens are orange or yellowish-brown and the fossa wall of the oospore is smooth or has a finely granulate ornamentation. In addition, scanning electronic microscopic examination demonstrated that the fossa walls have minute granulate structures that are compactly arranged. These observations contrast with a previous report that the oospore wall ornamentation of this taxon is reticulate. Since oospore wall ornamentation and the form of the dactyls in N. gracilens are essentially different from those of other infraspecific taxa of N. furcata sensu Wood (1965), N. gracilens should be maintained as a distinct morphological species within the genus Nitella.

Preliminary ESR study and relation with ion exchange thermodynamics of copper adsorbed on a biological ion exchanger — The Nitella flexilis cell wall

Precision sur la caracterisation de deux sites d'adsorption des ions cuivriques sur cette algue dont la paroi cellulaire a des proprietes d'echange de cation, dues aux anions polygalacturoniques (pectines)