Polytrichum Formosum Research Articles

UV-B tolerance of bryophyte species with different degrees of desiccation tolerance

We report on the efficiency of the primary photochemistry of photosystem II and potential thylakoid activity (represented by the variable fluorescence decrease ratio) of seven UV-B-treated bryophyte species during exposure and the subsequent recovery period. In Tortula ruralis, a strongly desiccation-tolerant grassland moss, there is no indication of any effects of UV-B irradiation. Desiccation-tolerant forest mosses ( Polytrichum formosum, Mnium hornum) are only temporarily affected by UV-B radiation or can even be positively affected by it ( Dicranum scoparium). The protective mechanism of desiccation-sensitive mesic species ( Plagiothecium undulatum, Leucobryum glaucum, Pellia epiphylla) is rapidly exhausted and they cannot tolerate increased UV-B radiation. These results support our view presented here that desiccation tolerance and UV-B tolerance involve similar defence mechanisms.

The Response of Different Cladonia Species after Treatment with Fertilizer or Lime in Heathland

The effect of deposition of different fertilizers and of lime on lichens was investigated under field conditions. Three terricolous lichens were tested: Cladonia floerkeana, C. furcata and C. portentosa. The lichens were exposed to three types of powdered fertilizer (NPK-, N-, P-fertilizer) and lime. The applied nutrients were recorded in lichen thalli and soil. The influence on lichen growth rate and vegetation cover was estimated over 2 years. The response was a clear change in vegetation cover with an exceptional stimulating effect of NPK on the moss Polytrichum formosum. A lethal effect was observed on Cladonia floerkeana following exposure to lime. NPK and P had the most significant stimulatory effect on C. furcata. Only NPK promoted the growth of C. portentosa and P, N or Ca had a negative effect.

Short-term thermal acclimation and heat tolerance of gametophytes of mosses

The ability of gametophytes of two Bryidae, Atrichum undulatum (Hedw.) P. Beauv. and Polytrichum formosum Hedw., to rapidly acquire thermotolerance was investigated by measuring chlorophyll a fluorescence and electrolyte leakage. Short-term acclimation of turgid shoots to elevated sublethal temperatures resulted in a small but significant increase in the heat stability of the photosynthetic apparatus and of cellular membranes by around 1 K, indicating that the heat hardening capacity of hydrated mosses is very low. While thermal adaptation occurred within few hours, dehardening required several days. The pattern of rapid thermal hardening and dehardening of turgid mosses resembles that of flowering plants. However, as opposed to the low potential for short-term thermal acclimation of hydrated gametophytes, a dramatic rise in heat resistance occurred with decline of the water content of the poikilohydric shoots, which was achieved either by equilibrating of the thalli at different relative humidities or by incubation in sugar solutions of various concentrations. The lower the water potential of the tissue the higher the heat tolerance of the shoots. The data show that in contrast to homoiohydric higher plants, in desiccation-resistant mosses changes in the water status of the thalli play the dominant role in short-term variations of thermal tolerance rather than specific heat hardening and dehardening reactions.

Relationships of geothermal bryophyte communities to soil characteristics at Thermal Meadow, Hotsprings Island, Queen Charlotte Islands, Canada

To determine the responses of cryptogams to the variations in temperature, pH, and humidity, we studied the vegetation of Thermal Meadow, Hotsprings Island, Queen Charlotte Islands, B.C., Canada. Only seven cryptogamic taxa were present in the samples: five mosses, one liverwort, and one lichen. Humidity limited the distribution, with Racomitrium lanuginosum and Cladina ciliata preferring the warmer, drier sites and Pleurozium schreberi and Dicranum scoparium preferring cooler, more moist sites. Polytrichum formosum was the most frequent taxon, occurring under both cool, moist conditions and warm, dry conditions. Aulacomnium palustre occurred in the mid temperature range mostly where humidity was fairly high. The pH ranged 6.8–7.2, providing insufficient variation for us to delimit species preferences.

A comparison of heavy metal deposition in selected Eastern European countries using the moss monitoring method, with special emphasis on the ‘Black Triangle’

The paper describes the use of moss analyses to compare heavy-metal pollution in Germany, Poland, the Czech Republic and the Slovak Republic. Special emphasis is placed on the regions where three countries meet within the area covered by the survey. In the countries participating, samples of Pleurozium schreberi, Scleropodium purum, Hypnum cupressiforme and Hylocomium splendens, Polytrichum formosum and Dicranum scoparium were collected at a total of 831 sampling points and analyzed for the elements Cd, Cr, Cu, Fe, Ni, Pb and Zn. The results were then presented in the form of coloured contour maps using the geographic information system (GIS) ARC-Info. The values found for heavy metals document the level of technical development in the countries concerned, which is generally characterized by a low standard in respect of emission-reducing systems. Moreover, the heavy-metal concentrations reflect the sources of emissions characteristic of the areas in which they occur. Above all, these are the primary use of coal (both hard coal and lignite) as an energy source, the chemical industry and ferrous- and non-ferrous metal working, which produce considerable emissions of particulate and fly ash, and also the use of leaded petrol. In most cases the moss method made it possible to identify the areas affected by the various industrial locations. The results show an increase in heavy-metal concentrations and higher average levels in the eastern parts of the countries compared. The paper also discusses the possibility of including the ‘three-country triangle’ further east in studies of Eastern Europe on the grounds that it constitutes another ‘Black Triangle’ in addition to the already familiar one.

New Three- and Tetraoxygenated Coumarin Glucosides from the Mosses Atrichum undulatum and Polytrichum formosum

Atrichum undulatum as well as Polytrichum formosum are containing each six different coumarin glycosides of which three are common to both species. From the nine different glycosides eight are new natural compounds. The structures have been elucidated spectroscopically.

Higher lead concentrations in the environment of former West Germany after the fall of the ‘Berlin Wall’

Biomonitoring for lead and chromium in the moss Polytrichum formosum has shown that in the years before the fall of the Berlin wall, the loading of these elements was decreasing. However in 1989/1990, localized increases in the concentration of lead in this moss in the vicinity of east-west motorways were detected. This was most likely due to the greater use of leaded petrol in eastern Germany. This observation is backed up by results from Bavaria at the Czech boarder, where localized increases in lead concentrations in the environment were found during this time period. As a result of the overall generally decreasing heavy metal loading in plants, deficiencies of essential macronutrients (Mg, Ca, K) seem to be lower also. This could be interpreted from data on Polytrichum formosum which showed an increase in these elements.

Time‐and‐site integrated long‐term biomonitoring of chemical elements by means of mosses

To use Polytrichum formosum for biomonitoring the heavy metal status of the environment and to obtain further information on the long‐term behaviour of Polytrichum concerning chemical substances, 12 chemical elements (Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Ni, Pb, Sr, and Zn) were quantitatively determined by AAS and AES/ICP measurements after sampling over regular intervals from 1985 to 1991. As already found in previous studies, all chemical elements are characterized by typical seasonal variations with maximum concentrations in the winter and lowest concentrations in the summer month due to the dilution effect of chemical elements caused by the higher biomass production of Polytrichum formosum in spring. An exception is the element K, snowing contrary behaviour throughout all the years with highest concentrations in the summer month which can be explained by the important physiological and osmolytical function of this element (e.g. for movement of the leaves). According to lower emission rates the concentratio...

Physiological Aspects of Sugar Exchange between the Gametophyte and the Sporophyte of Polytrichum formosum

The sporophyte of bryophytes is dependent on the gametophyte for its carbon nutrition. This is especially true of the sporophytes of Polytrichum species, and it was generally thought that sucrose was the main form of sugar for long distance transport in the leptom. In Polytrichum formosum, sucrose was the main soluble sugar of the sporophyte and gametophyte tissues, and the highest concentration (about 230 mm) was found in the haustorium. In contrast, sugars collected from the vaginula apoplast were mainly hexoses, with traces of sucrose and trehalose. p-Chloromercuribenzene sulfonate, a nonpermeant inhibitor of the cell wall invertase, strongly reduced the hexose to sucrose ratio. The highest cell wall invertase activity (pH 4.5) was located in the vaginula, whereas the highest activity of a soluble invertase (pH 7.0) was found in both the vaginula and the haustorium. Glucose uptake was carrier-mediated but only weakly dependent on the external pH and the transmembrane electrical gradient, in contrast to amino acid uptake (S. Renault, C. Despeghel-Caussin, J.L. Bonnemain, S. Delrot [1989] Plant Physiol 90: 913-920). Furthermore, addition of 5 or 50 mm glucose to the incubation medium induced a marginal depolarization of the transmembrane potential difference of the transfer cells and had no effect on the pH of this medium. Glucose was converted to sucrose after its absorption into the haustorium. These results demonstrate the noncontinuity of sucrose at the gametophyte/sporophyte interface. They suggest that its conversion to glucose and fructose at this interface, and the subsequent reconversion to sucrose after hexose absorption by haustorium cells, mainly governs sugar accumulation in this latter organ.

Relationship between frost tolerance and sugar concentration of various bryophytes in summer and winter

Frost resistance, measured via the photosynthetic capacity after freeze-thaw treatment, and concentrations of sucrose, glucose and fructose of thalli of seven species of Bryidae and one species of Marchantiidae were determined from January to March and June to September, respectively. A distinct increase in cold tolerance from summer to winter was found in Polytrichum formosum Hedw., Atrichum undulatum (Hedw.) P. Beauv., Plagiomnium undulatum (Hedw.) Kop., Plagiomnium affine (Funck) Kop., Mnium hornum Hedw. and Pellia epiphylla (L.) Corda. While the frost resistance of the musci differed in summer and winter by 15° to more than 25° C, the hardening capacity of the thalloid liverwort was comparably low. Except in Mnium hornum, the increase in frost hardiness was accompanied by rise of the sucrose concentration in the cells, but insignificant changes in glucose and fructose contents. In contrast, Brachythecium rutabulum (Hedw.) B.S.G. and Hypnum cupressiforme Hedw. already exhibited high frost tolerances in summer, which coincided with high sucrose levels in the tissue, comparable to those found in other musci during the winter. Highly frost-resistant musci had total sugar concentrations around 90-140 mM, of which at least 80% and often more than 90% was sucrose. Artificial degradation of sucrose during exposure of mosses to higher temperatures resulted in a decline in cold hardiness. The results signify that the concentration of sugars, mainly of sucrose, may be important for the frost tolerance of bryophytes.

Effects of rural roadside levels of nitrogen dioxide on Polytrichum formosum Hedw

Polytrichum formosum Hedw. was exposed to 60 nl litre −1 (122.4 μ m −3) NO 2 for 37 weeks in a closed chamber fumigation system. This concentration was chosen to simulate roadside levels in rural areas. Over an initial winter period (October–January) growth of existing shoots was stimulated by NO 2. When new growth was recorded in April and May, NO 2 pollution over winter and spring had resulted in a 36% reduction in new (< 1 cm) shoot production, and a 46% reduction in old shoots showing new growth. It is concluded that plants of Polytrichum formosum Hedw. growing near to roads may be adversely affected by NO 2 pollution. Adverse effects of NO 2 on plants and possible synergistic effects with other pollutants could cause growth reductions in sensitive species, thus affecting species composition of roadside vegetation.

Cation‐exchange properties and adaptation to soil acidity in bryophytes

summaryCation‐exchange processes of plant tissue are often hypothesized to affect ion uptake. Fixation of cations on exchange sites could either withdraw cations from further uptake, or concentrate them for the absorption sites. For a number of bryophyte taxa (Atrichum undulatum (Hedw.) P. Beauv., Homalothecium sericeum (Hedw.) B.S.&amp;G., Leucobryum glaucum (Hedw.) Angstr., Mnium hornum Hedw., Plagiomnium undulatum (Hedw.) T. Kop., Polytrichum formosum Hedw.), these contrasting hypotheses were tested by studying cation‐exchange properties and soil preference of populations with respect to soil acidity and soil exchangeable cations (Al, H, Fe, Mn, Ca, Mg, K). Acidiphilous and acidicline taxa (preference for soils with pH &lt; 5) with relatively lower cation‐exchange capacities tolerate high exchangeable aluminium levels and low calcium levels. Neutrocline taxa (preference for soils with pH &gt; 5) with higher cation‐exchange capacity avoid aluminium in the substrate and thrive on calcium‐rich substrates. Cation‐exchange properties therefore do not protect mosses against potentially toxic cations such as aluminium through a sequestration mechanism. However cation exchange sites may increase the availability of cations. High cation‐exchange capacity was indeed shown to favour fixation of aluminium over calcium ions and hence a low capacity is a prerequisite for taxa adapted to acid soils.

Use of Polytrichum formosum (moss) as a passive biomonitor for heavy metal pollution (cadmium, copper, lead and zinc)

After sampling over regular intervals from 1985 to 1987 the heavy metals Cd, Cu, Pb and Zn were quantitatively determined by atomic emission spectrometry/inductively coupled plasma in above-ground parts of the moss Polytrichum formosum (Hedw.). All metals present a typical summer-winter oscillation (seasonal variation), which is much greater than the “inter-stand” variation of Polytrichum formosum within the forest ecosystem under investigation. To obtain comparable results on a regional or global scale it is suggested to collect all samples of Polytrichum formosum for biomonitoring purposes in the last week of September.

The Proton Electrochemical Transmembrane Gradients Generated by the Transfer Cells of the Haustorium of Polytrichum formosum and Their Use in the Uptake of Amino Acids

The epidermal cells of the sporophyte haustorium of Polytrichum formosum are modified into transfer cells. These cells are located in a strategic place allowing them to control the exchanges between the two generations. Their plasmalemma creates proton gradients (Deltapsi and DeltapH) which increase during the development of the sporophyte. As the sporophyte grows from 2 to 4 cm long, the pH of the incubation medium of the haustoria decreases from 5.2 to 4.3, and the transmembrane potential difference (PD) hyperpolarizes form -140 to -210 millivolts. These gradients become rapidly larger than that generated by the plasmalemma of the basal cells of the sporophyte. They are used to energize the uptake of the solutes present in the apoplast of the gametophyte, particularly the amino acids. Below 20 micromolar alpha-aminoisobutyric acid uptake in the transfer cells is mediated by a saturable system and is optimal at acidic pH (4.0 and 4.5). It is strongly inhibited by compounds dissipating both Deltapsi and DeltapH (10 micromolar carbonylcyanide-m-chlorophenyl hydrazone) or only Deltapsi (0.1 molar KCl). The absorption of alpha-aminoisobutyric acid and of the other neutral amino acids tested induces an alkalinization of the medium and a depolarization of membrane potential difference which is concentration dependent. These data show that the uptake of amino acids by the transfer cells of the haustorium is a secondary translocation (proton-amino acid symport) energized by a primary translocation (proton efflux). More particularly, they show that transfer cells possess a membrane enzymic equipment particularly efficient to achieve the uptake of the solutes leaked in the apoplast from other cell types.

Fluctuations of element concentrations during the growing season of Polytrichum formosum (Hedw.)

Fourteen elements (Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Ni, Pb, Sr, Ti, and Zn) were quantitatively determined by AES/ICP in aboveground parts of the endohydric moss Polytrichum formosum (Hedw.) after sampling over regular intervals from 1985 to 1987. With the exception of K, Mg, and Zn all elements showed a large continuous fluctuation (> 30%) during the growing season. Four different patterns of seasonal variation were found: (1) large seasonal variations of element concentrations (∼80%) with maximum concentrations in winter and lowest concentrations in the summer months (Al, Fe, Cr, Mg, Pb, and Ti), (2) smaller seasonal variations (∼50%) with maximum concentrations in winter and lowest concentrations in summer (Ba, Ca, Cd, Cu, Sr), (3) slight seasonal variations (∼30%) with maximum concentrations in the summer (K), and (4) slight seasonal changes (∼30%) with maximum concentrations in the winter (Mg and Zn). The relative biological variance of element concentrations between 9 different stands of Polytrichum formosum decreases in the following sequence: Ti, Al, Pb, Fe, Cr, Ni, Ba, Ca, Cu, Cd, K, Mg, Sr, Zn. The relative biological variance of individual elements is generally lower than the variance in element concentrations caused by seasonal changes. Because of its high biological variance for most elements investigated (seasonal as well as between different stands of Polytrichum formosum) this moss should only be used as a passive bioindicator, if all other environmental parameters are standardized.

Evolution de la structure plastidiale et des reserves polysaccharidiques au cours de la déshydratation des gamétophytes feuillés duPolytrichum formosumHedw. (Polytrichales)

AbstractThe effects of a 24 h dehydration period on plastid ultrastructure and their starch content have been studied on the leafy gametophyte of a poikilohydrous moss Polytrichum formosum Hedw. It has been shown that desiccation induces a swift resorption of the starch grains in the plastids of the meristematic cells of the shoot apex without any major disorganisation of the thylakoids. However starch grains are preserved in the dehydrated tissues of the adult leaves. The starch hydrolysis is continued with a marked increase of the sucrose concentration to this may be attributed an osmoregulatory role in the first stages of the water loss. Upon rehydration the plastid ultrastructure is entirely restored with new starch inclusions appearing in less than 4 h.

Absorption of Some Amino Acids by Sporophytes Isolated from Polytrichum formosum and Ultrastructural Characteristics of the Haustorium Transfer Cells

The absorption of 14C-labelled amino acids (glycine, threonine and α-aminoisobutyric acid) by the isolated sporophyte of Polytrichum formosum takes place mainly in the haustorium. The isolation of the sporophyte does not alter the absorption capacity of its haustorium nor its ultrastructure, in particular that of its peripheral transfer cells.

Echinenone (ß,ß-Caroten-4-one) from the Gametophyte of Polytrichum formosum (Bryophyta, Musci)

Summary For the first time the keto-carotenoid echinenone has been found in the gametophyte of some samples of the moss Polytrichum formosum , besides the normal chloroplast pigments. This carotenoid was not detected in the sporophyte. Pollution by echinenone containing microorganisms (blue-green algae, bacteria) could be excluded. Protonemata and moss plantlets cultivated from the spores of those echinenone containing mosses have been able to biosynthesize this keto-carotenoid, too.

EFFECT OF DESICCATION ON DNA SYNTHESIS AND THE CELL CYCLE OF THE MOSS POLYTRICHUM FORMOSUM

SUMMARYThe effects of a 24‐h dehydration period on the mitotic and DNA‐synthetic activities have been studied in the meristematic cells of the leafy gametophyte of the moss Polytrichum formosum. During the first 2 h of water stress the mitotic index decreased dramatically, and after 6 h none of the cells was observed in division. It is concluded that the stress provokes not only cessation, but also completion of the mitotic phase, so that all the cells of the desiccated plants become interphasic. On rehydration, a period of 24 h was necessary for the first cell to enter division. After 4 h of recovery from water stress, DNA synthesis resumed in the nuclei of a few cells indicating that replication processes were not injured to any marked extent by the desiccation treatment. However, a clear increase in the number of nuclei entering the S phase was only observed 24 h after the start of rehydration. It is suggested that the effect of the dehydration period is to prevent the cells which are situated in G1 or G2 phases to enter respectively the phases of S and M of the cell cycle immediately upon rehydration. In any case the result is to delay, for about 24 h from the beginning of rehydration, the return of proliferative activity. These data are compared with those previously obtained on the metabolism of water‐stressed mosses.

Beobachtungen zur biologie und ultrastruktur der moosbewohnenden thekamöbe Nebela tincta (Rhizopoda)

Summary The present paper includes observations on the population, the structure and ultrastructure of the shell and of the cyst, and the vertical distribution in the moss as well as observations on the excystment of Nebela tincta. The population of Nebela tincta in the moss Polytrichum formosum is characterized biometrically as a distinct group. The theca of Nebela tincta consists of innumerable siliceous platelets which are embedded into a layer of a homogeneous cement at the outside. The platelets are of different size and shape. They originate from various thecamoebean species, thus representing xenosomes in the theca of Nebela tincta. The platelet-pattern differs from theca to theca, not only with respect to platelet variety, but also in the extent of surface covering by the platelets. There is no indication towards a production of platelets by Nebela tincta itself. The stages of duration (cysts) are characterized by the plasma being motionless and rounded off within a homogeneous cystic membrane. The cystic membrane fastens the plasma to the plug by which the mouth of the theca is closed. This plug is composed of organic waste particles and more or less parallel layers of the same types of siliceous platelets which are used in the construction of the shell. The vertical distribution of Nebela tincta in the moss exhibits a maximum in the zone of decomposition of the green leaflets. Excystment occurs by uptake of water, rupture of the cystic membrane, and disintegration of the plug. Both the cystic membrane and the components of the plug are phagocytized. The possible functions of the lateral pores during encystment, excystment, and active life are discussed.