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Thin layer chromatography of fructans from Porella platyphylla . The plants were extracted with 80 % ethanol. Lanes A, B and D : P . platyphylla extracts. Lane C : Helianthus tuberosus inulin standard. SUC, sucrose ; DP 3–DP 10, fructans of degree of polymerization 3–10.
Source publication
The major soluble carbohydrates in the desiccation-tolerant leafy liverwort Porella platyphylla (L.) Lindb. are sucrose and a homologous series of fructans including the trisaccharide 1-kestose. Exogenous glucose and fructose (10 mol m−3) did not affect the composition of the soluble carbohydrate pool. Sucrose caused an increase in the fructan pool...
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... by GC and fructans by the resorcinol assay. proportion of low-molecular-weight fructan (80 % ethanol soluble) and high-molecular-weight fructan (hot-water-soluble) varied between fresh, desiccated and rehydrated leaves ( Table 1). The fructans in the 80 % ethanol extract were separated by TLC which revealed a series from DP 3 to DP 10 ( Fig. 1). The trisaccharide had the same mobility as 1-ketose in the Helianthus fructan standard. Lanes A, B and D in Figure 1 illustrate the fructan pattern from a range of extracts. The larger proportion of high DP fructan in lane A was not consistently associated with any particular ...
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... trisaccharide had the same mobility as 1-ketose in the Helianthus fructan standard. Lanes A, B and D in Figure 1 illustrate the fructan pattern from a range of extracts. The larger proportion of high DP fructan in lane A was not consistently associated with any particular treatment. ...
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... , extracts from desiccated and rehydrated tissues were mixed to detect possible inhibitory factors in the rehydrated extracts. Oxygen exchange was measured in a liquid phase oxygen electrode (Hansatech LD2, Kings Lynn, UK). The electrode chamber contained 0 n 2 g f. wt. of tissue and 2 cm $ of 10 mol m − $ NaHCO in 10 mol $ m − $ Tricine-KOH buffer (pH 7 n 5) at 25 m C. PPFD was 1500 μ mol m − # s − " for the photosynthesis measurements. The extent of vacuole development in P . platyphylla leaf cells was determined by neutral red staining. The leaves were stained in 100 mol m − $ Tris-malate buffer at pH 7 n 5 containing 1500 mol m − $ sucrose, 7 n 5 mol m − $ polyvinylpyrrolidone (molecular wt 40 000) and 0 n 02 % (w \ v) neutral red before viewing with a microscope. Where probabilities are quoted the data have been subject to analysis of variance. Errors, where indicated, are standard deviations. The soluble carbohydrate pool of P. platyphylla The soluble carbohydrates in 80 % ethanol and water extracts of P . platyphylla were identified by PC, TLC and GC. Fructans and sucrose were the major components while glucose and fructose were present at considerably lower concentration (Tables 1, 2). Traces of compounds with the same retention time as trehalose and raffinose were detected by GC but their identity has not been confirmed. The fructans were detected by a ketose-specific resorcinol method (Farrar, 1993) and the low amount of fructose detected by GC makes a very small contribution to the concentrations quoted. The proportion of low-molecular-weight fructan (80 % ethanol soluble) and high-molecular-weight fructan (hot-water-soluble) varied between fresh, desiccated and rehydrated leaves (Table 1). The fructans in the 80 % ethanol extract were separated by TLC which revealed a series from DP 3 to DP 10 (Fig. 1). The trisaccharide had the same mobility as 1-ketose in the Helianthus fructan standard. Lanes A, B and D in Figure 1 illustrate the fructan pattern from a range of extracts. The larger proportion of high DP fructan in lane A was not consistently associated with any particular treatment. The soluble carbohydrate composition of P . platyphylla was not greatly affected by an external supply of sugars (10 mol m − $ ). Glucose, fructose and sucrose supplied for 4 d had little effect on the concentration of glucose, fructose or sucrose in the plants (Table 2). Fructan was slightly increased by sucrose feeding. Dark starvation for 4 d caused a 70 % decrease in sucrose, glucose and fructose, whereas fructan was decreased by 44 %. The fructans are therefore conserved in preference to sucrose. Photosynthetic oxygen evolution was unaffected by glucose and fructose and by dark starvation. However sucrose feeding decreased the rate of photosynthesis by 25 % ( P 0 n 05). Sucrose feeding and dark decreased the rate of respiration by 40 and 29 % respectively ( P 0 n 05) (Table ...
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... , extracts from desiccated and rehydrated tissues were mixed to detect possible inhibitory factors in the rehydrated extracts. Oxygen exchange was measured in a liquid phase oxygen electrode (Hansatech LD2, Kings Lynn, UK). The electrode chamber contained 0 n 2 g f. wt. of tissue and 2 cm $ of 10 mol m − $ NaHCO in 10 mol $ m − $ Tricine-KOH buffer (pH 7 n 5) at 25 m C. PPFD was 1500 μ mol m − # s − " for the photosynthesis measurements. The extent of vacuole development in P . platyphylla leaf cells was determined by neutral red staining. The leaves were stained in 100 mol m − $ Tris-malate buffer at pH 7 n 5 containing 1500 mol m − $ sucrose, 7 n 5 mol m − $ polyvinylpyrrolidone (molecular wt 40 000) and 0 n 02 % (w \ v) neutral red before viewing with a microscope. Where probabilities are quoted the data have been subject to analysis of variance. Errors, where indicated, are standard deviations. The soluble carbohydrate pool of P. platyphylla The soluble carbohydrates in 80 % ethanol and water extracts of P . platyphylla were identified by PC, TLC and GC. Fructans and sucrose were the major components while glucose and fructose were present at considerably lower concentration (Tables 1, 2). Traces of compounds with the same retention time as trehalose and raffinose were detected by GC but their identity has not been confirmed. The fructans were detected by a ketose-specific resorcinol method (Farrar, 1993) and the low amount of fructose detected by GC makes a very small contribution to the concentrations quoted. The proportion of low-molecular-weight fructan (80 % ethanol soluble) and high-molecular-weight fructan (hot-water-soluble) varied between fresh, desiccated and rehydrated leaves (Table 1). The fructans in the 80 % ethanol extract were separated by TLC which revealed a series from DP 3 to DP 10 (Fig. 1). The trisaccharide had the same mobility as 1-ketose in the Helianthus fructan standard. Lanes A, B and D in Figure 1 illustrate the fructan pattern from a range of extracts. The larger proportion of high DP fructan in lane A was not consistently associated with any particular treatment. The soluble carbohydrate composition of P . platyphylla was not greatly affected by an external supply of sugars (10 mol m − $ ). Glucose, fructose and sucrose supplied for 4 d had little effect on the concentration of glucose, fructose or sucrose in the plants (Table 2). Fructan was slightly increased by sucrose feeding. Dark starvation for 4 d caused a 70 % decrease in sucrose, glucose and fructose, whereas fructan was decreased by 44 %. The fructans are therefore conserved in preference to sucrose. Photosynthetic oxygen evolution was unaffected by glucose and fructose and by dark starvation. However sucrose feeding decreased the rate of photosynthesis by 25 % ( P 0 n 05). Sucrose feeding and dark decreased the rate of respiration by 40 and 29 % respectively ( P 0 n 05) (Table ...
Citations
... Fructan, a third type of carbohydrate and energy storage component, is involved in metabolism, produced in a small fraction (15%) of the Angiosperms (van der Meer et al. 1994;van den Ende et al. 2011). The non-vascular bryophytes also synthesise fructans (Maass and Craigie 1964;Suleiman et al. 1979;Marschall 1998;Marschall 2010). Fructans as non-structural carbohydrates are the primary products of photosynthesis, key regulators of adaptation to environmental stress, provide substrates for growth and metabolism (Liu et al. 2018), act as antioxidants, scavenging reactive oxygen species and preventing cell damage under abiotic stress conditions (Peshev et al. 2013). ...
... Fructans as non-structural carbohydrates are the primary products of photosynthesis, key regulators of adaptation to environmental stress, provide substrates for growth and metabolism (Liu et al. 2018), act as antioxidants, scavenging reactive oxygen species and preventing cell damage under abiotic stress conditions (Peshev et al. 2013). The role of fructans as storage carbohydrates, their function in desiccation tolerance and low temperature stress is well emphasized in higher plants (Marschall 2010), but there is only few number of articles focusing on the physiology of fructan producing bryophytes (Marschall et al. 1998;Marschall 2010). Fructan-accumulating species contain only traces (~1% ) of starch, which means that fructan is a real alternative to starch. ...
... Capitula and stem parts of Sphagnum species were extracted with 80% ethanol followed by hot water (Marschall et al. 1998). Supernatant and sediment extracts were also used for assays. ...
The prevalence of fructan-producing plants is primarily restricted to the temperate climate, while they are virtually absent from the tropical regions. Although the Sphagnum genus has a worldwide distribution and considerable ecological importance, it is relatively rare for the whole of tropical Africa. The island of Réunion is located in the tropical climate and has a rich Sphagnum flora containing 14 species. Sphagnum species - as an exception amongst mosses - synthesise fructan and have a considerable amount of sucrose as well. No data on fructan content of Sphagnum occuring in tropical habitats have been reported so far. This short paper provided data first, based on experimental results, on the non-structural carbohydrate pool, especially fructans in Sphagnum species from a tropical region, from Réunion Island. Fructans accounted for 2-4% of the total soluble carbohydrates in the examined Sphagnum species. We compared the fructan content of eight Sphagnum species collected from Réunion in relation to their altitude zone and their distribution. The species generally increased their fructan accumulation as the altitude increased. Our preliminary experimental results show that fructans as an alternative storage carbohydrate to starch may play a role in the ecological niche preference of the Sphagnum species according to altitudinal zones.
... Sorbitol is rather widely documented in liverworts (e.g. Marschall et al. 1998) but also in mosses (e.g. Pejin et al. 2012). ...
The same population of the polytrichaceous moss Polytrichum formosum was
studied over four different periods of the year, analysing its carbohydrate and
polyphenolic content and dynamics related to environmental seasonal changes. A
total of 18 different types of sugars (including mono-, di-, tri- and tetra-saccharides) and four sugar alcohols were determined. Chlorogenic acid was the most
represented among the 10 detected phenolic compounds. As inferred by the sugar
content, sucrose, fructose and glucose were the most dominant sugars, but it is
worth mentioning the abundance of trehalose and turanose at least during one of
the observed seasons. The presence of four trisaccharides and one tetrasaccharide
within P. formosum should be highlighted, as well as the first reports of turanose,
isomaltotriose, panose and rhamnose within this species. The quantitative changes
over the year clearly demonstrate carbohydrate dynamics in relation to seasonal
climatic variation. Sugars are shown to be significant constitutive molecules within
P. formosum, but also physiologically active compounds, i.e. signalling and energy
storage and supplier molecules. We assume that phenolics have moss-supportive
effects during oxidative stress and biotic interaction.
... BSC macro-phyla (bryophytes and lichens) are soil primary producers (Warren et al., 2019). The decomposition of their cellulose rich tissues releases monomers, typically glucose (Gunina and Kuzyakov, 2015) providing a supply of sugars that is a plentiful energy source (Marschall et al., 1998) consumed by heterotrophic secondary producers such as bacteria and fungi (Davis, 1981). Further, leafy liverworts contain a range of soluble carbohydrates, such as sucrose and fructan, which play roles in various aspects of their poikilohydric abilities (Marschall et al., 1998). ...
... The decomposition of their cellulose rich tissues releases monomers, typically glucose (Gunina and Kuzyakov, 2015) providing a supply of sugars that is a plentiful energy source (Marschall et al., 1998) consumed by heterotrophic secondary producers such as bacteria and fungi (Davis, 1981). Further, leafy liverworts contain a range of soluble carbohydrates, such as sucrose and fructan, which play roles in various aspects of their poikilohydric abilities (Marschall et al., 1998). Sucrose acts as a fuel source that supports the rehydration-induced repair and recovery mechanisms, while fructan stabilizes macro-molecules during desiccation and prevents sucrose crystallization (Marschall et al., 1998). ...
... Further, leafy liverworts contain a range of soluble carbohydrates, such as sucrose and fructan, which play roles in various aspects of their poikilohydric abilities (Marschall et al., 1998). Sucrose acts as a fuel source that supports the rehydration-induced repair and recovery mechanisms, while fructan stabilizes macro-molecules during desiccation and prevents sucrose crystallization (Marschall et al., 1998). The uptake and utilization of these soluble sugars ensures the bacterial communities can maintain the activities essential to their establishment and survival (Gunina and Kuzyakov, 2015;Slate et al., 2019). ...
Biological soil crusts (BSCs) are communities of bryophytes, lichens, bacteria, and fungi and are the primary colonizing communities in early successional landscapes. In early ecosystem development BSCs often improve the physical and chemical conditions while also promoting soil microbial communities. Although BSCs are considered ecosystem engineers in many early successional environments, the links between BSC functional processes and their developmental stage are unclear, especially in landscapes recovering from anthropogenic disturbances. In this study we examined natural BSC development over a 30-year chronosequence on two mining impacted landscapes in both boreal and arctic regions of Canada. Using High Throughput Sequencing (HTS), we found similar ubiquitous ruderal bryophytes and bacteria species common at both study areas, but significant differences in lichen and fungal community structure between the two locations. In addition, community assembly of BSC macro (bryophytes and lichens) and micro (bacteria and fungi)-phyla changed over the first 30 years of recovery at both mine sites, however, these changes were unique to each study location. We observed nutrient accumulation in the crust layer but did not find clear trends in available nutrients or gas flux over time. Instead, changes in our functional measurements were associated with colonization by specific BSC species. Further, the bacterial community at both mines seemed to be responding to changes in the bryophyte communities as they developed over time. This suggests that the establishment of bryophyte communities in early succession may be driving micro-phyla BSC community composition. A holistic view of BSCs as they develop over time in relation to their functional abilities needs further investigation, and this study provides insight into these interactions. This knowledge will improve both our understanding of early stage BSC development and our ability to develop restoration techniques to effectively restore landscapes disturbed by anthropogenic activities.
... In M. polymorpha, chlorophyll fluorescence (López-Pozo et al., 2019), survival after desiccation (Pence et al., 2005;Akter et al., 2014), cell ultrastructure (Duckett et al., 2014), and gene expression (Marks et al., 2019) have been studied in some of the desiccation experiments, but surprisingly, gas exchange measurements are lacking. In P. platyphylla desiccation stress studies have included measurements of chlorophyll fluorescence (Proctor, 2003), O 2 gas exchange (Hinshiri and Proctor, 1971), ion leakage (Brown and Buck, 1979), cell metabolite content (Marschall et al., 1998;Marschall, 2010), cell ultrastructure (Sütő and Marschall, 2016), and photosynthetic 14 CO 2 uptake (Gupta, 1977), among others (Table S2 at Zenodo). ...
Desiccation-rehydration experiments have been employed over the years to evaluate desiccation tolerance of bryophytes (Bryophyta, Marchantiophyta, and Anthocerotophyta). Researchers have applied a spectrum of protocols to induce desiccation and subsequent rehydration, and a wide variety of techniques have been used to study desiccation-dependent changes in bryophyte molecular, cellular, physiological, and structural traits, resulting in a multifaceted assortment of information that is challenging to synthesize. We analysed 337 desiccation-rehydration studies, providing information for 351 species, to identify the most frequent methods used, analyse the advances in desiccation studies over the years, and characterize the taxonomic representation of the species assessed. We observed certain similarities across methodologies, but the degree of convergence among the experimental protocols was surprisingly low. Out of 52 bryophyte orders, 40% have not been studied, and data are lacking for multiple remote or difficult to access locations. We conclude that for quantitative interspecific comparisons of desiccation tolerance, rigorous standardization of experimental protocols and measurement techniques, and simultaneous use of an array of experimental techniques are required for a mechanistic insight into the different traits modified in response to desiccation. New studies should also aim to fill gaps in taxonomic, ecological, and spatial coverage of bryophytes.
... In addition to these roles, some studies also investigated the possible alterations of the fructans pool and the photosynthetic responses of plants. For example, the depression of the photosynthesis did not affect the levels and fructans and the high DP pool was maintained even though mono-and disaccharide pools were affected (Marschall et al., 1998;Thomas and James, 1999;Marschall, 2010). In a similar study on different varieties of wheat and chicory, the depression of photosynthesis did not affect the accumulation of fructans, although hexoses pool was negatively correlated to the photosynthesis rate (Martínez-Carraseo et al., 1993;Monti et al., 2005). ...
Drought, one of the major abiotic stresses affecting plants, is characterized by a decrease of water availability, resulting in a decrease of the water potential (Ψ) of the cells. One of the strategies of plants in resisting to this low Ψ and related stresses is regulating their water-plant relation and the interplay between Ψsolutes and the turgor pressure (Ψp). This regulation avoids the dehydration induced by low Ψ and is resulting from the accumulation of specific molecules which induce higher tolerance to water deficit and also other mechanisms that prevent or repair cell damages. In plants, fructans, the non-structural carbohydrates (NSC), have other physiological functions than carbon reserve. Among these roles, fructans have been implicated in protecting plants against water deficit caused by drought. As an efficient strategy to survive to this abiotic stress, plants synthesize fructans in response to osmotic pressure in order to osmoregulate the cellular flux, therefore, protecting the membrane damage and maintaining Ψp. Although different studies have been conducted to elucidate the mechanisms behind this strategy, still the concept itself is not well-understood and many points remain unclear and need to be elucidated in order to understand the causal relation between water deficit and fructans accumulation during water scarcity. This understanding will be a key tool in developing strategies to enhance crop tolerance to stressful dry conditions, particularly under the changing climate prediction. This review aims to give new insights on the roles of fructans in the response and resistance of plants to water deficit and their fate under this severe environmental condition.
... Bryophytes produce and accumulate a vast array of other molecules exerting biological effects, including saccharides, lipids, vitamins and nitrogen-and sulfur-containing compounds. Some examples are reported in Figure 4. Beside the traditional saccharides, for example sucrose, which can be found in both flowering plants and bryophytes, tri-, oligo-and polysaccharides, such as the rare fructooligosaccharide 1-ketose extracted from the moss Rhodobryum ontariense and the liverwort Porella platyphylla [123,124], are unique for bryophytes. Lipids found in bryophytes include (i) membrane lipids, such as sterols (in particular, in higher evolved mosses have been found stigmasterol, campesterol and sitosterol), fatty acids and glycerol-, phosphor-and sphingo-lipids; (ii) storage lipids, such as triacylglycerols and sterol esters; (iii) surface lipids involved in the formation of part of the cuticle, such as cutin and waxes and (iv) signaling lipids, including phosphoinositides and oxylipins [125]. ...
Usually regarded as less evolved than their more recently diverged vascular sisters, which currently dominate vegetation landscape, bryophytes seem having nothing to envy to the defensive arsenal of other plants, since they had acquired a suite of chemical traits that allowed them to adapt and persist on land. In fact, these closest modern relatives of the ancestors to the earliest terrestrial plants proved to be marvelous chemists, as they traditionally were a popular remedy among tribal people all over the world, that exploit their pharmacological properties to cure the most different diseases. The phytochemistry of bryophytes exhibits a stunning assortment of biologically active compounds such as lipids, proteins, steroids, organic acids, alcohols, aliphatic and aromatic compounds, polyphenols, terpenoids, acetogenins and phenylquinones, thus it is not surprising that substances obtained from various species belonging to such ancestral plants are widely employed as antitumor, antipyretic, insecticidal and antimicrobial. This review explores in particular the antifungal potential of the three Bryophyta divisions—mosses (Musci), hornworts (Anthocerotae) and liverworts (Hepaticae)—to be used as a sources of interesting bioactive constituents for both pharmaceutical and agricultural areas, providing an updated overview of the latest relevant insights.
... Fresh roots were extracted in 80% ethanol solution followed by hot water treatment (10 ml g −1 FW) and centrifuged at 10 000 g for 10 min at 4 • C as previously described (Marschall, Proctor and Smirnoff 1998;Zhang et al. 2017). The ethanolic extract and the previously mentioned fermentation culture were used to analyze soluble carbohydrates. ...
... For the in vitro test, acarbose (1, 2, 5, 10 or 20 mM) and pyridoxal hydrochloride (2.5, 5, 10 or 20 mM) were added to reaction mixtures (200 mM citrate buffer, pH 5.5 and 20 mM sucrose). The doses applied were chosen according to previous studies (Marschall, Proctor and Smirnoff 1998;Bonfig et al. 2010). Then, 20 μl of the supernatant prepared for the previously described soluble invertase assay was added to the mixture and maintained at 30 • C for 30 min. ...
... Rice seedlings inoculated with or without Ph. liquidambaris were cultured in a low-N nutrient solution with or without 10 mM of pyridoxal hydrochloride, which has been previously reported (Marschall, Proctor and Smirnoff 1998) and confirmed to inhibit root invertase activity ( Figure S10). In addition, 10 mM of pyridoxal hydrochloride did not cause visible damage to rice seedlings or fungal growth. ...
The mechanisms underlying nitrogen (N)-regulated plant-fungi interactions are not well understood. N application modulates plant carbohydrate (C) sinks and is involved in the overall plant-fungal association. We hypothesized that N regulates plant-fungi interactions by influencing the carbohydrate metabolism. The mutualistic fungus Phomopsis liquidambaris was found to prioritize host hexose resources through in vitro culture assays and in planta inoculation. Rice-Ph. liquidambaris systems were exposed to N gradients ranging from N-deficient to N-abundant conditions to study whether and how the sugar composition was involved in the dynamics of N-mediated fungal colonization. We found that root soluble acid invertases were activated, resulting in increased hexose fluxes in inoculated roots. These fluxes positively influenced fungal colonization, especially under N-deficient conditions. Further experiments manipulating the carbohydrate composition and root invertase activity through sugar feeding, chemical treatments and the use of different soil types revealed that the external disturbance of root invertase could reduce endophytic colonization and eliminate endophyte-induced host benefits under N-deficient conditions. Collectively, these results suggest that the activation of root invertase is related to N deficiency-enhanced endophytic colonization via increased hexose generation. Certain combinations of farmland ecosystems with suitable N inputs could be implemented to maximize the benefits of plant-fungi associations.
... Asterisks indicate significant differences (Student's t test, *p ≤ 0.05, **p ≤ 0.01) endogenous SAG12 of cotton and thus postpone the leaf senescence ( Supplementary Fig. 2). However, high level of sugars in leaves would repress the expression of photosynthetic genes and thereby inhibit net photosynthesis (Marschall et al. 1998;Rook and Bevan 2003). Therefore, retaining more sugar in the leaf would produce two negative consequences for the plant: decreasing the photosynthetic capacity of leaves, and reducing the nutrient remobilization from senescing leaves to the sink organs. ...
Key message
Sink-specific expression of a sucrose transporter protein gene from the C4 plant maize can promote carbohydrate accumulation in target tissues and increase both fiber and seed yield of cotton.
Abstract
Sucrose is the principal form of photosynthetic products transported from source tissue to sink tissue in higher plants. Enhancing the partition of carbohydrate to the target organ is a promising way to improve crop productivity. The C4 plant Zea mays exhibits a substantially higher rate of export of photosynthates than many C3 plants, and its sucrose transporter protein ZmSut1 displays important role in sucrose allocation. To investigate how use of ZmSUT1 gene to increase the fiber and seed yield of cotton, in this study, we expressed the gene in cotton under a senescence-inducible promoter PSAG12 and a seed coat-specific promoter BAN, respectively. We show that senescence-induced expression of ZmSUT1 results in an increase of sugar accumulation in leaves. Although the leaf senescence was postponed in PSAG12::ZmSUT1 cotton, the photosynthetic rate of the leaves was decreased. In contrast, seed coat-specific expression of the gene leads to an increase of sugar accumulation in fibers and bolls, and the leaf of transgenic BAN::ZmSUT1 cotton displayed higher photosynthetic capacity than the wild type. Importantly, both fiber and seed yield of transgenic BAN::ZmSUT1 cotton are significantly enhanced. Our data indicate the potential of enhancing yield of carbohydrate crops by the regulation of sugar partitioning.
... Ultrastructural studies of the liverwort Southbya nigrella by Pressel et al. (2009) showed that oil bodies remain intact during dehydration, but change drastically in shape and consistency during rehydration. Marschall et al. (1998) proposed that during drying some of the cell's soluble carbohydrates are likely converted to oil body terpenoids, and that oil bodies in this way could act as a store of carbon to buffer the soluble carbohydrate pool. Thus, some of the terpenoids in liverworts may function in desiccation tolerance, serving as modulators of cytoplasmic osmotic potential. ...
Bryophytes are close extant relatives of the ancestral land plant. As such, they have retained many innovations that had enabled the adaptation of early land plants to the terrestrial environment. One of such important innovations is the elaboration of an enormously diverse array of secondary metabolites. This article reviews current knowledge of terpenoid secondary metabolites, which constitute the largest family of plant metabolites, in bryophytes from three perspectives: chemical diversity, biosynthesis, and biological functions. The diversity of terpenoids in bryophytes, particularly in liverworts, is enormously rich. More than 1600 terpenoids have been reported from this plant group. While many terpenoids are observed in both bryophytes and seed plants, some are unique to bryophytes. It is just the beginning for us to understand the molecular and biochemical basis underlying terpenoid biosynthesis in bryophytes. Compared to seed plants, which have only one type of terpene synthase genes, so-called typical plant terpene synthase genes, bryophytes employ not only typical plant terpene synthase genes but also another class of terpene synthase genes called microbial-terpene synthase-like (MTPSL) genes for terpenoid biosynthesis. Biochemical studies suggest the MTPSLs are largely responsible for the terpenoid diversity in bryophytes, particularly sesquiterpenes and monoterpenes. Existing literature indicates that terpenoids made by bryophytes have important functions in diverse biological and ecological processes, particularly as defenses against biotic and abiotic stresses. The continued development of genomic resources and molecular tool kit for bryophytes will accelerate characterization of terpenoids biosynthesis and their biological functions in this important lineage of plants.
... Positive carbon balance is essential to surviving repeated cycles of drying and wetting; significant growth requires continuously wet periods of a few days or more. The mechanisms of desiccation-tolerance in bryophytes, including expression of LEA proteins, high content of non-reducing sugars (Marschall et al. 1998) and effective antioxidant and photo-protection, are at least partly constitutive, allowing survival of rapid drying, and employ an active rehydration-induced repair and recovery mechanism. During their recovery phase the changes in gene expression resulting from mRNA sequestration and alterations in translational controls elicited upon rehydration are also important to repair processes following rewetting (Proctor et al. 2007b). ...
