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The aquatic bryophyte Fontinalis antipyretica Hedw. (A) visualized through µ-XCT scanning imaging of the colony structure (B, D) and transversal (C, E) cut, in dehydrated (B,C) and hydrated (D, E) states.
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In the last decade, several works showed that even bryophytes from aquatic environments, if slowly dehydrated, can cope with desiccation in a response like the one from desert bryophytes. This led to the hypothesis that, if bryophytes from contrasting habitats can have similar responses, desiccation tolerance (DT) is partially inductive and not onl...
Citations
... If this is the case, then plant density should be less important in wetter habitats such as pools and pond margins where water loss can easily be replenished. In other bryophytes, colony structure and morphology was found be associated with differences in drying rates [23], and increased plant density was correlated with increased water retention capacity across species [11]. ...
... S. inundatum, having permanent water access, should not be under strong selection pressure for higher plant density. Environmentally correlated variations in density have been previously documented for a number of bryophytes including Sphagnum [11] and, in some bryophyte species, density was shown to associated with improved desiccation resilience [23]. S. capillifolium had the highest density and is also the species growing highest above the water table at the collection site, forming dense hummocks. ...
Peatlands have become a focal point in climate mitigation strategies as these ecosystems have significant carbon sequestration capacities when healthy but release CO2 and other greenhouse gases when damaged. However, as drought episodes become more frequent and prolonged, organisms key to the functioning of some peatlands are increasingly under pressure from desiccation. The Sphagnum mosses, which tend to keep their ecosystem waterlogged and many of whom promote peat formation, are only mildly desiccation-tolerant in comparison to other mosses. The role of Sphagnum anatomy and colony structure is poorly understood in the context of desiccation resilience. Using four different Sphagnum species belonging to four different subgenera and positions along the gradient of the water table, we show that plant morphological traits and colony density are important determinants of water storage capacity. Our results show that, as previously postulated, the majority of the water is stored in an easily exchangeable form, probably extracellularly, and that plant morphological traits, specifically the type and presence of branches, are major contributors to water storage and can explain some of the interspecies variation. We also show that plant density is another important determinant for water storage capacity as higher densities hold larger quantities of water per unit of biomass for all four species, which increases resilience to desiccation. The results presented here suggest that species choice and planting density should receive more attention when considering peatland restoration strategies.
... However, despite the lack of significant changes in the abundance of bryophyte functional groups with tree canopy cover, our results indicate that species may experience stressful conditions (i.e., high radiation and low water availability) during the early stages of post-fire succession. Indeed, compared to late successional species, early successional mosses exhibit higher desiccation tolerance and enhanced water use efficiency (densely packed shoots minimize evaporative water loss and confer protection against photoinhibition; Bates, 1998;Glime, 2017;Cruz de Carvalho et al., 2019), reflecting differences in environmental conditions along the successional gradient. ...
... It is acknowledged that bryophytes' structure and maturity change the capillarity features of the species and have functional consequences both in their potential water holding ability [24][25][26][27] and in their resistance to water loss [28]. For instance, the morphological organization of the shoots in colonies [29], leaf arrangement (e.g., succubous and incubous) [30], presence of leaf hair-points [31], thickness (e.g., costa, lamellae) and shape (e.g., lobules, water sacs) [28,[32][33][34], presence of surface wax [32], cell thickenings, and cell specialization (e.g., hyaline cells) are some of the features that improve water holding capacity. Consequently, the architecture of bryophytes acts as an efficient strategy to achieve, in a balanced way, the water economy and light capture, as well as carbon and nutrient acquisition. ...
... However, knowledge regarding the contribution of different species at different elevations, particularly in rich temperate ecosystems, is practically nonexistent. In fact, many of the results regarding the water content of bryophytes cannot be directly compared to this study, as species were not individually examined but rather grouped into categories such as "epiphytes" [41,42,54,57,58] or "soil and logs" bryophyte' communities [46], while other studies focused on different properties such as desiccation tolerance [29]. ...
... For instance, F. acicularis displays helmet-shaped lobules; C. brevipilus has white hair points; and T. brachydontium exhibits twisted leaves on drying [49]. Interestingly, in the study conducted by Cruz de Carvalho and colleagues [29], the moss C. pyriformis showed a lower recovery rate after rapid drying, a feature attributed to its looser colony structure. The same feature may help to explain the consistent low values of FWC of the congeneric C. brevipilus found in this study. ...
Bryophytes play a crucial role in the ecosystem’s water compartment due to their unique ability to retain water. However, their role within temperate native ecosystems is mostly unknown. To address this knowledge gap, a study was conducted on Terceira Island (Azores), focusing on 14 bryophyte species found at different altitudes (40 m, 683 m, and 1012 m); five samples were collected monthly, per species and location, and their fresh, saturated, and dry weights were examined in the laboratory; four species were collected from more than one site. Generalized linear models (GLM) were used to assert the influence of climate factors (temperature, precipitation, and relative humidity) and environmental variables on two water indicators: field water content (FWC) and relative water content (RWC). None of the examined factors, per se, were able to explain all cases. Species appear to respond to climate according to a limiting factor effect: at lower elevations, precipitation was determinant, while at medium elevations, FWC was influenced by a combination of precipitation and relative humidity. At higher elevations, temperature was retained for seven of the nine studied species. The RWC values indicated that the 14 bryophyte species remained hydrated throughout the year but rarely reached their maximum water-holding capacity, even at the highest altitude. Understanding the mechanisms by which native bryophytes acquire, store, and release water is crucial for comprehending the resilience of native vegetation in the face of climate change. This knowledge can also enable the development of strategies to mitigate the effects of climate change and protect vital water resources.
... The N to P scaling for vascular plant leaves is closely associated with relations of mass-based nutrient concentration to specific leaf area [8], which involve areamass relations depending on the quantity of hydraulic or mechanical tissues in the lamina. In most bryophytes, however, the structure of colony determines the area-mass relation, as it is colony structure that controls water retention in capillary spaces [9] and light interception [6]. Canopy mass per area, a parameter depicting bryophyte colony structure, correlated to photosynthetic rate is analogous to the relations found for the leaf economic spectrum [10], while no relationship was found at the shoot level. ...
... F v /F m measurements were taken in the morning, before the start of the light period, so that the plants had been under 12 h of dark adaptation. The latter is related to PSII reaction centers, which are open after dark adaptation and which decrease under dehydration stress; thus, this can be used as a measure of survival under drought conditions in bryophytes [17,60,61]. Chlorophyll fluorescence emissions were assessed using a pulseamplitude modulation fluorometer (model MINI-PAM, WALZ, Effeltrich, Germany) with a light saturation pulse of~5000 µmol m −2 s −1 . ...
Desiccation tolerance (DT) is the ability of an organism or structure to dry completely and subsequently survive in that air-dry state. Hornworts are excellent plant models to study desiccation effects as they have contrasting life histories which are likely associated with DT. We tested whether (1) epiphytic species had more efficient DT responses to drying and postrehydration than non-epiphytic species and whether (2) “green” spores were more sensitive than non-green spores to extreme drying. Hornwort species were collected from the Atlantic Forest of Rio de Janeiro, Brazil. We studied five species (gametophytes and spores: Dendroceros crispus, D. crispatus, Nothoceros vincentianus, Phaeoceros carolinianus; and only spores of Anthoceros lamellatus), using different relative humidity values, drying durations, and postrehydration conditions. All DT treatments affected the chlorophyll fluorescence (Fv/Fm) of gametophytes, with species-specific responses. D. crispatus and D. crispus (epiphytes) performed better than P. carolinianus and N. vincentianus, with fast recovery of Fv/Fm values postrehydration. The ability of non-green spores of P. carolinianus and A. lamellatus and green spores of D. crispus to support desiccation led us to reject our second hypothesis. The DT strategies of hornworts highlighted the trade-offs that are important in spore dispersal and plant establishment, such as fast colonization in Dendroceros spp. and potential spore soil banks in Phaeoceros and Anthoceros species.
... Among the 18 plots we collected, 7 showed symbiosis of moss species, and 5 of them have B. unguiculata distribution and have very high species coverage (table 1). This is because dense B. unguiculata plants can store more water and facilitate plant community development [25,26]. It also indicates that B. unguiculata is dominant in interspecific interactions in the study area. ...
The local dominant mosses were used to study the revegetation of the high and steep slope of the open-pit mine. Based on the improved Line Intercept Method (LIM), the rapid screening of dominant pioneer mosses for mine reforestation was carried out and the impact of habitat on the development of wild mosses was preliminarily explored. The results showed that 6 species of mosses belonging to 5 families were found in the representative plots, and Barbula unguiculata was the dominant species among the pioneer mosses. The important values of mosses were as follows: Barbula unguiculata > Brachymenium exile > Haplocladium microphyllum > Amblystegium serpens,> Sematophyllum subpinnatum > Thuidium glaucinoides. Altitude, temperature and humidity are important factors affecting the development of wild Barbula unguiculata. The improved LIM was applied in field experiment to obtain and quickly screen dominant moss, this method was also of great significance to other research areas. It is a development direction for mine regreening engineering to select superior local moss species suitable for the regional environment as the re greening seed source.
... The ease of transformation and the existence of wellcharacterized mutants in many of the developmental and stress signalling pathways in Physcomitrium are valuable resources to test the functionality of other Sphagnum genes. Lastly, our data support earlier observations that Sphagnum is able to tolerate significant levels of dehydration without losing photosynthetic capacity, and this should be taken into consideration when modelling the global responses of peatlands to changes in climate patterns especially precipitation (Wagner and Titus, 1984;Schipperges and Rydin, 1998;Proctor, 2000;Oliver et al., 2005;Proctor et al., 2007;Dise, 2009;Hájek and Vicherová, 2014;Cruz de Carvalho et al., 2019;Rastogi et al., 2020). ...
Mosses of the genus Sphagnum are the main components of peatlands, a major carbon-storing ecosystem. Changes in precipitation patterns are predicted to affect water relations in this ecosystem, but the effect of desiccation on the physiological and molecular processes in Sphagnum are still largely unexplored. Here we show that different Sphagnum species have differential physiological and molecular responses to desiccation but, surprisingly, this is not directly correlated with their position in relation to the water table. In addition, the expression of drought responsive genes is increased upon water withdrawal in all species. This increase in gene expression is accompanied by an increase in ABA, supporting a role for ABA during desiccation responses in Sphagnum. Not only do ABA levels increase upon desiccation, but Sphagnum plants pre-treated with ABA display increased tolerance to desiccation, suggesting that ABA levels play a functional role in the response. In addition, many of the ABA signalling components are present in Sphagnum and we demonstrate, by complementation in Physcomitrium patens, that Sphagnum ABI3 is functionally conserved. The data presented here, therefore, support a conserved role for ABA in desiccation responses in Sphagnum.
... Bryophytes show poikilohydry and desiccation tolerance that is the optimal pattern of adaptation at their scale and, possess water content equivalent to that of their environment. Bryophytes are considered to be desiccation-tolerant plants, i.e., capable of reviving from an air-dry state (de Carvalho et al., 2019). According to Gao et al. (2018), most bryophytes can survive −20 to −40 MPa desiccation for short durations, which is beyond the range that most crop species can withstand. ...
Dehydration and rejuvenation during rehydration is the salient feature of certain plants which can withstand drought. The present study was undertaken to justify the tolerance capacity of Campylopus flexuosus, the moss of the Ponmudi belts of Thiruvananthapuram, against dehydration followed by rehydration. Fresh leafy plants of C. flexuosus were hydrated, afterwards dried, and rehydrated under in vitro environment. In the course of loss of water from cells, the relative water content of desiccated thallus was reduced after 4 h with intense inward curling. Upon rehydration, the RWC was regained 85% of its initial water content within hours. The rehydrated thallus showed the normal morphology. Photosynthetic parameters like chlorophyll b (1.01 to 1.56 μg g –1 ), and total carotenoid (0.251 to 0.514 μg g –1 ) increased remarkably in the desiccated state. Superoxide radical (O2 _) content increased (11.4 nmol/g FW), resulting in an oxidative burst during desiccation. Consequently, antioxidant enzymes such as catalase (0.369 U mg protein −1), superoxide dismutase ( 2.68 to 6.02 Units mg−1), peroxidase ( 0.12 μmol min−1 g−1 protein) and glutathione reductase ( 312 Units mg−1 protein) activities were up-regulated in the desiccated thallus to ameliorate oxidative damage. Increased malondialdehyde (1.08 nmol g−1 FW) content during desiccation substantiates membrane damage and loss of its integrity. During desiccation, the osmolytes sucrose and proline (27.6 and 2.57 μmol/g FW respectively) were enhanced to maintain cell structure integrity. After rehydration, biochemical and morphological properties were maintained similar to hydrated conditions. Thus, the study reflects the unique adaptations of the moss to tide over desiccation tolerance.
... They help improve soil stability, fix basic nutrients like nitrogen (N) and carbon (C), and increase the organic matter content in soils, facilitating other plants to grow roots and serving as a habitat for other organisms [1]. They are also susceptible to rapid dehydration under low relative humidity and quickly resume metabolic activity upon rehydration [2][3][4]. Furthermore, mosses can recover quickly after an environmental perturbation, being one of the earlier colonizers among biological soil crust (BSC) components [5]. Moreover, they are totipotent, i.e., any vegetative moss tissue can be a propagule from which grows a new plant [6]. ...
... It would be expected that acrocarpous species, such as B. argenteum, T. nitida, and T. squarrosa, would grow more at higher temperatures and with longer photoperiods. These smaller species with cushion life forms can equilibrate more slowly with the relative humidity of their environment and therefore resist desiccation better [4,33]. However, this was only observed for T. nitida where the growth achieved at 20 °C and with a 20/4 h photoperiod was much higher than for other temperatures. ...
Bryophytes are poikilohydric organisms that play a key role in ecosystems, while some of them are also resistant to drought and environmental disturbances but present a slow growth rate. Moss culture in the laboratory can be a very useful tool for ecological restoration or the development of urban green spaces (roof and wall) in the Mediterranean region. Therefore, we aim to: (i) determine the optimal culture conditions for the growth of four moss species present in the Mediterra-nean climate, such as Bryum argenteum, Hypnum cupressiforme, Tortella nitida, and Tortella squarrosa; (ii) study the optimal growth conditions of the invasive moss Campylopus introflexus to find out if it can be a threat to native species. Photoperiod does not seem to cause any recognisable pattern in moss growth. However, temperature produces more linear but slower growth at 15 °C than at 20 and 25 °C. In addition, the lower temperature produced faster maximum cover values within 5-8 weeks, with at least 60% of the culture area covered. The study concludes that the culture of moss artificially in the organic gardening substrate without fertilisers is feasible and could be of great help for further use in environmental projects to restore degraded ecosystems or to facilitate urban green spaces in the Mediterranean area. Moreover, this study concludes that C. introflexus could successfully occupy the niche of other native moss species, especially in degraded areas, in a future global change scenario.
... leaf frequency). Indeed, moss colony density and height have been reported to correlate positively with water retention capacity (Proctor, 1982;Elumeeva et al., 2011), shoot morphology controls dehydration rate of mosses (Cruz de Carvalho et al., 2019), and leaf width is positively related to water retention in Sphagnum mosses (Bengtsson et al., 2020). However, to our knowledge, there is no empirical evidence that these hydrology-related traits affect cyanobacterial colonization of mosses. ...
Background and aims:
Cyanobacteria associated with mosses represent a main nitrogen (N) source in pristine, high latitude and altitude ecosystems due to their ability to fix N2. However, despite progress made regarding moss-cyanobacteria association, the factors driving the large interspecific variation in N2 fixation activity between moss species remain elusive. The aim of the study was to identify the traits of mosses that determine cyanobacterial colonization and thus, N2 fixation activity.
Methods:
Four moss species varying in N2 fixation activity were used to assess cyanobacterial abundance and activity to correlate it with moss-traits (morphological, chemical, water-balance traits) for each species.
Key results:
Moss-hydration rate was one of the pivotal traits, explaining 56% and 38% variation in N2 fixation and cyanobacterial colonization, respectively, and was linked to morphological traits of the moss species. Higher abundance of cyanobacteria was found on shoots with smaller leaves, and with a high-frequency of leaves. High phenol concentration inhibited N2 fixation but not colonization. These traits driving interspecific variation in cyanobacterial colonization, however, are also affected by the environment, and lead to intraspecific variation. Approximately 24% of paraphyllia, filamentous appendages on Hylocomium splendens stems, were colonized by cyanobacteria.
Conclusions:
Our findings show that interspecific variations in moss traits drive differences in cyanobacterial colonization and thus, N2 fixation activity among moss species. The here-identified key traits that control moss-associated N2 fixation and cyanobacterial colonization could lead to improved predictions of N2 fixation in different moss species as a function of their morphology.
