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Ricinus communis is an important oilseed crop worldwide and is also considered one of the best potential plants for salt‐affected soil improvement in northeast China. However, little is known about photosynthesis and carbohydrate metabolism in this plant, nor the distribution of carbohydrates in cotyledons and roots under salinity stress.In the present study, seedling growth, gas exchange parameters (PN, E, gs and Ci), carbohydrate (fructose, sucrose, glucose, soluble sugar and starch) metabolism and related enzymes and genes were measured in Ricinus plants.Under salt stress, PN of cotyledons decreased significantly (P < 0.05), resulting in weak photosynthetic capacity. Furthermore, salt stress increased sucrose and glucose content in cotyledons, but decreased soluble sugar and starch content. However, sucrose increased and starch decreased in roots. This may be correlated with the increasing sugar metabolism under salinity, including notable changes in sugar‐related enzyme activities (SPS, SuSy, α‐amylase and β‐amylase) and gene expression of RcINV, RcSUS, RcAmY, RcBAM and RcGBE1.The results suggest that salinity reduces photosynthesis of cotyledons, alters carbohydrate allocation between cotyledons and roots and also promotes starch utilization in cotyledons and starch biosynthesis in roots, leading to a functional imbalance between cotyledons and roots. Together, these findings provide insights into the crucial role of sugar metabolism in improving salt‐tolerance of Ricinus during the early seedling growth stage. [ABSTRACT FROM AUTHOR]

Understanding how plants adjust their requirements for different N forms can help elucidate plant coexistence strategies in N‐limited desert ecosystems. To understand the mechanisms involved, we investigated whether two desert herbs can directly absorb dissolved organic nitrogen (N) and tested whether the patterns changed over different growth stages.Two dominant herbaceous species, Astragalus arpilobus and Arnebia decumbens, from the southern edge of the Gurbantunggut desert, China, were selected. Short‐term (24 h) 15N‐labelled tracer (15N‐NO3, 15N‐NH4, 2‐13C‐15N‐Glycine) treatments were conducted at two soil depths (0–5 cm and 5–15 cm) in the season of rapid growth (June) and in the peak biomass season (July). Enrichment in 13C and 15N was assessed in the two species receiving glycine.The ratio 13C:15N was 0.21–1.39 at the 24‐h harvest, suggesting that approximately 10.5–69.5% of glycine had been absorbed. The amount of absorbed 15N was significantly affected by species, month, soil depth and N form. The two species absorbed most 15N from the 0–5 cm soil layer, and the absorption rate in July was higher than that in June. The absorption of 15N‐NO3 and 15N‐NH4 was significantly higher than that of 2‐13C‐15N‐Glycine.The results indicate that these herbs could use amino acids in the N‐deficient desert ecosystem. The two co‐existing species used different forms of inorganic N for their requirements and maintained a specific preference throughout various growth stages. [ABSTRACT FROM AUTHOR]

Growth and functioning of Sphagnum mosses are closely linked to water level and chemistry. Sphagnum mosses occur in wet, generally acidic conditions, and when buffered, alkaline water is known to negatively impact Sphagnum. The effects of time, dose and species‐specific responses of buffered, alkaline water on Sphagnum are largely unknown.We investigated the effects of bicarbonate and calcium on the survival, growth and physiological functioning of seven Sphagnum species occurring in contrasting environments, from raised bogs to (rich) fens. Mosses were submerged in different concentrations of bicarbonate and calcium solutions for 10 weeks under climate‐controlled circumstances.After 2 weeks, all species exposed to the high bicarbonate treatment (2.0 mM) showed severe potassium leakage and swift discoloration. In contrast, species showed differential responses to the intermediate bicarbonate treatment (0.8 mM), some with a later onset of potassium leakage. S. squarrosum, S. teres & S. contortum generally persisted the longest, with all species dying after 6 to 10 weeks. Calcium alone, in contrast, negatively affected S. squarrosum, S. teres & S. contortum, causing discoloration and potassium leakage.Our study shows enrichment with bicarbonate, but not calcium, is detrimental for most Sphagnum species tested. A mechanistic model was developed that is consistent with dose and duration dependence and the species specificity. Future conservation and restoration measures for Sphagnum‐dominated habitats and Sphagnum farming (cultivation, production and harvest of Sphagnum moss biomass) should limit flooding with bicarbonate‐rich waters while investigating new management options, like acidifying surface waters to lower bicarbonate levels. [ABSTRACT FROM AUTHOR]

Persistence and colonization by tree species in an environment following a fire depends on the effects on seed germination and seedling development. We used seeds of Kielmeyera coriacea and Qualea parviflora as a model to test the effects of high temperatures on germination and initial development of tree seedlings.We exposed the seeds to heat flow (70, 100, 130, 150 or 170 °C) for 2 or 5 min and compared the germination with that of unheated seeds (control). Seedlings were then harvested after 3, 7 or 15 days to evaluate aerial and root mass, root:shoot ratio, presence of cotyledon opening, true leaves, and secondary roots.We found no effect on germination for seeds exposed to temperatures ≥150 °C. However, germination was significantly reduced for seeds exposed to 100 °C for both 2 and 5 min. The mass of 15‐day‐old K. coriacea seedlings was smaller when seeds were heated at 70 °C for 5 min or at temperatures higher or equal to 100 °C. Qualea parviflora seedlings did not show any difference in mass, but there were marginal differences in the presence of roots and the opening of cotyledons. Kielmeyera coriacea seedlings allocated biomass faster than Q. parviflora.High temperatures affect both quantity and quality of germinable seeds, as well as biomass allocation during initial seedling development. These factors may explain the decrease in seedlings observed after fire, suggesting a bottleneck effect that influences population dynamics and species persistence in systems with frequent fires. [ABSTRACT FROM AUTHOR]

Abscisic acid (ABA), gibberellins (GA), auxins, cytokinins (CK) and ethylene (ET) are the "classical" phytohormones, while more recent discoveries are jasmonates (JA), salicylic acid (SA), polyamines (PAs), brassinosteroids (BR) and strigolactones. Some molecules (such as phytohormones, kinases and special organic or inorganic components) have been demonstrated as central hubs for gene regulation, signalling or metabolism in plant stress responses. However, it is very difficult to accurately distinguish the roles of AMF through direct or indirect pathways, since plant stress responses are commonly followed by concurrent changes in plant growth and nutrient availability. Plant growth and development undergo continuous environmental changes, including exposure to biotic and/or abiotic stresses. [Extracted from the article]

Waterlogging and salinity impair crop growth and productivity worldwide, with their combined effects being larger than the additive effects of the two stresses separately. Here, a common forage tetraploid Lotus corniculatus (cv. San Gabriel) and a diploid L. corniculatus accession, collected from a coastal area with high frequency of waterlogging–saline stress events, were evaluated for tolerance to waterlogging, salinity and these two stresses combined. We hypothesize that, due to its environmental niche, the diploid accession would show better adaptation to combined waterlogging–saline stress compared to the tetraploid L. corniculatus.Plants were evaluated under control conditions, waterlogging, salinity and a combined waterlogging–saline treatment for 33 days. Shoot and root growth were assessed, together with chlorophyll fluorescence and gas exchange measurements. Results showed that salinity and waterlogging effects were more severe for the tetraploid accession, with a larger effect being observed under the combined stress condition.Concentrations of Na+, Cl− and K+ were measured in apical and basal leaves, and in roots. A larger accumulation of Na+ and Cl− was observed under both saline and combined stress treatments for the tetraploid L. corniculatus, for which ion toxicity effects were evident.The expression of CLC gene, coding for a Cl− transporter, was only increased in diploid L. corniculatus plants in response to the combined stress condition, suggesting that ion compartmentalization mechanisms were induced in this accession. Thus, this recently characterized L. corniculatus could be used for the introduction of new tolerance traits in other Lotus species used as forage. [ABSTRACT FROM AUTHOR]

Within an Open Science project, research was carried out to describe to the public of the Ghirardi Botanic Garden (BS, Lombardy, Italy) the invisible features of plants. This work is dedicated to Scutellaria altissima L. (Lamiaceae).Micromorphological, histochemical and phytochemical investigations were conducted on the vegetative and reproductive organs to correlate the structures involved in the emission of substances and their unique productivity. This work reports volatile organic compound (VOC) profiles of leaves and flowers and the composition of essential oil (EO) obtained from aerial parts of plants cultivated in Italy that have never been described before.Three morphotypes of glandular trichomes were observed: peltate, short‐stalked capitate and long‐stalked capitate. Peltate trichomes were the main producers of terpenes, short‐stalked capitates of polysaccharides and long‐stalked capitates of terpenes and polyphenols. The leaf VOC profile showed heterogeneous composition, with non‐terpene derivatives as the major chemical class (71.04%), while monoterpene hydrocarbons represented almost the totality of the flower (99.73%). The leaf presented a higher number of total (37 versus 11) and exclusive (33 versus 7) compounds. (Z)‐3‐Hexenol acetate was most abundant in the leaf and (E)‐β‐ocimene in the flower. Four common compounds were detected: β‐pinene, β‐caryophyllene, γ‐muurolene and germacrene‐D. The EO contaied 21 compounds, dominated by β‐caryophyllene, linalool and hexahydrofarnesyl acetone.This research allowed us to correlate morphotypes of the secretory structures with the production of secondary metabolites, with the aim of providing the public of the Ghirardi Botanic Garden with a dedicated iconographic approach, which accounts for olfactory perception linked to S. altissima. [ABSTRACT FROM AUTHOR]

Nutrient resorption, one of the most important strategies for plant nutrient conservation, is significantly affected by soil fertility. However, the effects of experimentally altered soil fertility on plant N and P resorption are poorly understood.The potential nutrient resorption response mechanisms of the dominant species Leymus chinensis to six N addition levels (0, 2.5, 5, 10, 20 and 40 g·N·m−2·year−1), two P addition levels (0 and 10 g P·m−2·year−1) and their interactions were studied after 3 years of treatments in a temperate meadow steppe.In both green leaves and culms, N and P addition significantly increased N and P concentrations, respectively. Nitrogen addition led to a decrease in the N resorption efficiency (NRE) of both leaves and culms. Within each N treatment, P addition decreased the P resorption efficiency (PRE) of both leaves and culms and the NRE of leaves, except in the N2.5 treatment. Both NRE and PRE in leaves were higher than those in culms under N and P addition conditions. The nutrient concentrations and resorption efficiency were significantly correlated with the soil nutrient availability.Our results suggest that plants rely more on nutrient absorption from the soil, reducing the proportion of elements obtained through nutrient resorption in nutrient‐rich environments. [ABSTRACT FROM AUTHOR]

Plants are known to respond to warming temperatures. Few studies, however, have included the temperature experienced by the parent plant in the experimental design, in spite of the importance of this factor for population dynamics.We investigated the phenological and growth responses of seedlings of two key temperate tree species (Fagus sylvatica and Quercus robur) to spatiotemporal temperature variation during the reproductive period (parental generation) and experimental warming of the offspring. To this end, we sampled oak and beech seedlings of different ages (1–5 years) from isolated mother trees and planted the seedlings in a common garden.Warming of the seedlings advanced bud burst in both species. In oak seedlings, higher temperatures experienced by mother trees during the reproductive period delayed bud burst in control conditions, but advanced bud burst in heated seedlings. In beech seedlings, bud burst timing advanced both with increasing temperatures during the reproductive period of the parents and with experimental warming of the seedlings. Relative diameter growth was enhanced in control oak seedlings but decreased with warming when the mother plant experienced higher temperatures during the reproductive period.Overall, oak displayed more plastic responses to temperatures than beech. Our results emphasise that temperature during the reproductive period can be a potential determinant of tree responses to climate change. [ABSTRACT FROM AUTHOR]

Several Cerrado tree species have traits and structures that protect from fires. The effectiveness of a trait depends on the fire regime, especially the frequency. We used Vochysia elliptica, a common Cerrado tree, as a model to test whether different fire frequencies alter crown architecture and flower, fruit and seed production.We analysed the effect of fire on the production of inflorescences, fruits and seeds, as well as seed germination and tree architecture of 20 trees in each of three plots of a long‐term ecological experiment managed with different fire regimes: burned every 2 years (B), burned every 4 years (Q) in mid‐dry season and an area protected from fire (C).We found a large negative effect of fire frequency on crown architecture and on flower and fruit production. Trees in C and Q had significantly more main branches and a larger crown area than trees in B. At its peak, a tree in C was expected to produce 2.4 times more inflorescences than Q, and 15.5 times more than B, with similar magnitudes for fruits. Sixty per cent of trees in B and 10% in Q produced no fruits.The differences in architecture might explain the reduction in sexual reproduction due to a smaller physical space to produce flowers at the branch apices. Resource limitation due to plant investment to replace burned vegetative parts may also decrease sexual reproduction. Our results indicate potentially severe consequences of high fire frequencies for population dynamics and species persistence in Cerrado communities. [ABSTRACT FROM AUTHOR]

Orchids are a classic angiosperm model for understanding biotic pollination. We studied orchid species within two species‐rich herbaceous communities that are known to have either hymenopteran or dipteran insects as the dominant pollinators, in order to understand how flower colour relates to pollinator visual systems.We analysed features of the floral reflectance spectra that are significant to pollinator visual systems and used models of dipteran and hymenopteran colour vision to characterise the chromatic signals used by fly‐pollinated and bee‐pollinated orchid species.In contrast to bee‐pollinated flowers, fly‐pollinated flowers had distinctive points of rapid reflectance change at long wavelengths and a complete absence of such spectral features at short wavelengths. Fly‐pollinated flowers also had significantly more restricted loci than bee‐pollinated flowers in colour space models of fly and bee vision alike.Globally, bee‐pollinated flowers are known to have distinctive, consistent colour signals. Our findings of different signals for fly pollination is consistent with pollinator‐mediated selection on orchid species that results from the distinctive features of fly visual systems. [ABSTRACT FROM AUTHOR]

Nutations of plant organs are significantly affected by the circatidal modulation in the gravitational force exerted by the Moon and Sun (lunisolar tidal acceleration, Etide). In a previous study on nutational rotations of stem apices, we observed abrupt alterations in their direction and irregularities of the recorded trajectories. Such transitions have not yet been analysed in detail.Peppermint plants were continuously recorded with time‐lapse photography and aligned with contemporaneous time courses of the Etide estimates. Each nutational stem tip movement path was assigned to one of two groups, depending on its geometry, as: (i) regular elliptical movements and (ii) irregular movements (with a random type of trajectory). Analyses of the correlation between the plant nutation trajectory parameters and Etide, as well as of the trajectory geometry of the individual plants were performed.The trajectory geometry of young mint stem apices was related to the velocity of the apex rotation and significantly affected by the gravitational force estimated from the Etide. A low velocity of nutational movement, associated with the random character of the trajectory, usually occurred simultaneously with local minima or maxima of Etide. As the mint plant ages, the transitions in the stem tip trajectory were limited; no correspondence with Etide dynamics was observed.The results indicate that the plant tip geometry path transitions with respect to the changing gradient of lunisolar tidal acceleration could be interpreted as manifestation of a continuous accommodation of the shoot apical part to the state of minimum energy dissipation. [ABSTRACT FROM AUTHOR]

Based on the elemental composition of major biochemical molecules associated with different biological functions, the 'growth rate hypothesis' proposed that organisms with a higher growth rate would be coupled to lower C:N, especially lower C:P and N:P ratios. However, the applicability of the growth rate hypothesis for plants is unclear, especially for shrubs growing under different water supply.We performed an experiment with eight soil moisture levels (soil water content: 4%, 6%, 8%, 13%, 18%, 23%, 26% and 28%) to evaluate the effects of water availability on leaf C:N:P stoichiometry in the shrub Zygophyllum xanthoxylum.We found that leaves grew slowly and favored accumulation of P over C and N under both high and low water supply. Thus, leaf C:P and N:P ratios were unimodally related to soil water content, in parallel with individual leaf area and mass. As a result, there were significant positive correlations between leaf C:P and N:P with leaf growth (u).Our result that slower‐growing leaves had lower C:P and N:P ratios does not support the growth rate hypothesis, which predicted a negative association of N:P ratio with growth rate, but it is consistent with recent theoretical derivations of growth–stoichiometry relations in plants, where N:P ratio is predicted to increase with increasing growth for very low growth rates, suggesting leaf growth limitation by C and N rather than P for drought and water saturation. [ABSTRACT FROM AUTHOR]

Amino acids represent an important component in the diet of the Venus flytrap ( Dionaea muscipula), and supply plants with much needed nitrogen resources upon capture of insect prey. Little is known about the significance of prey-derived carbon backbones of amino acids for the success of Dionaea's carnivorous life-style., The present study aimed at characterizing the metabolic fate of 15N and 13C in amino acids acquired from double-labeled insect powder. We tracked changes in plant amino acid pools and their δ13C- and δ15N-signatures over a period of five weeks after feeding, as affected by contrasting feeding intensity and tissue type ( i.e., fed and non-fed traps and attached petioles of Dionaea)., Isotope signatures ( i.e., δ13C and δ15N) of plant amino acid pools were strongly correlated, explaining 60% of observed variation. Residual variation was related to contrasting effects of tissue type, feeding intensity and elapsed time since feeding. Synthesis of nitrogen-rich transport compounds ( i.e., amides) during peak time of prey digestion increased 15N- relative to 13C- abundances in amino acid pools. After completion of prey digestion, 13C in amino acid pools was progressively exchanged for newly fixed 12C. The latter process was most evident for non-fed traps and attached petioles of plants that had received ample insect powder., We argue that prey-derived amino acids contribute to respiratory energy gain and loss of 13CO2 during conversion into transport compounds ( i.e., 2 days after feeding), and that amino-nitrogen helps boost photosynthetic carbon gain later on ( i.e., 5 weeks after feeding). [ABSTRACT FROM AUTHOR]

Naturalists Fritz and Hermann Müller hypothesised that heteranthery often leads to a division of labour into 'feeding' and 'pollinating' stamens; the latter often being as long as the pistil so as to promote successful pollination on the bees' back. In many buzz-pollinated species of Senna, however, the so-called pollinating stamens are short and not level with the stigma, raising the question of how pollen is shed on the bees' back. Here we explore a mechanism called 'ricochet pollination'. We test whether division of labour is achieved through the interaction between short lower stamens and strongly concave 'deflector petals'., We studied the arrangement and morphology of the floral organs involved in the ricochet pollination, functioning of the flowers through artificial sonication and observed the interactions between bees and flowers in the field., The middle stamens are adapted to eject pollen downwards, which can be readily collected on the bee mid legs. Most of the pollen is ejected towards the deflector petal(s). Pollen from this set of stamens is more likely to contribute to pollination. The pollen grains seem to ricochet multiple times against the deflector petals to eventually reach the bee's back., The pollen ricochet mechanism promotes a division of labour by involving additional floral organs, such as petals, reinforcing the Müllers' division-of-labour hypothesis. However, alternative, non-multiexclusive hypotheses could be explored in genus Senna and other angiosperm species. [ABSTRACT FROM AUTHOR]

Orbital movement of the Moon generates a system of gravitational fields that periodically alter the gravitational force on Earth. This lunar tidal acceleration (Etide) is known to act as an external environmental factor affecting many growth and developmental phenomena in plants. Our study focused on the lunar tidal influence on stem elongation growth, nutations and leaf movements of peppermint., Plants were continuously recorded with time-lapse photography under constant illumination as well in constant illumination following 5 days of alternating dark-light cycles. Time courses of shoot movements were correlated with contemporaneous time courses of the Etide estimates. Optical microscopy and SEM were used in anatomical studies., All plant shoot movements were synchronised with changes in the lunisolar acceleration. Using a periodogram, wavelet analysis and local correlation index, a convergence was found between the rhythms of lunisolar acceleration and the rhythms of shoot growth. Also observed were cyclical changes in the direction of rotation of stem apices when gravitational dynamics were at their greatest. After contrasting dark-light cycle experiments, nutational rhythms converged to an identical phase relationship with the Etide and almost immediately their renewed movements commenced. Amplitudes of leaf movements decreased during leaf growth up to the stage when the leaf was fully developed; the periodicity of leaf movements correlated with the Etide rhythms., For the fist time, it was documented that lunisolar acceleration is an independent rhythmic environmental signal capable of influencing the dynamics of plant stem elongation. This phenomenon is synchronised with the known effects of Etide on nutations and leaf movements. [ABSTRACT FROM AUTHOR]

With the projected increase in drought duration and intensity in future, small water bodies, and especially the terrestrial-aquatic interfaces, will be subjected to longer dry periods with desiccation of the sediment. Drought effects on the plant-sediment microorganism carbon continuum may disrupt the tight linkage between plants and microbes which governs sediment carbon and nutrient cycling, thus having a potential negative impact on carbon sequestration of small freshwater ecosystems. However, research on drought effects on the plant-sediment carbon transfer in aquatic ecosystems is scarce. We therefore exposed two emergent aquatic macrophytes, Phragmites australis and Typha latifolia, to a month-long summer drought in a mesocosm experiment., We followed the fate of carbon from leaves to sediment microbial communities with 13 CO2 pulse labelling and microbial phospholipid-derived fatty acid ( PLFA) analysis., We found that drought reduced the total amount of carbon allocated to stem tissues but did not delay the transport. We also observed an increase in accumulation of 13C-labelled sugars in roots and found a reduced incorporation of 13C into the PLFAs of sediment microorganisms., Drought induced a switch in plant carbon allocation priorities, where stems received less new assimilates leading to reduced starch reserves whilst roots were prioritised with new assimilates, suggesting their use for osmoregulation. There were indications that the reduced carbon transfer from roots to microorganisms was due to the reduction of microbial activity via direct drought effects rather than to a decrease in root exudation or exudate availability. [ABSTRACT FROM AUTHOR]

We studied biotically pollinated angiosperms on Macquarie Island, a remote site in the Southern Ocean with a predominately or exclusively dipteran pollinator fauna, in an effort to understand how flower colour affects community assembly. We compared a distinctive group of cream-green Macquarie Island flowers to the flora of likely source pools of immigrants and to a continental flora from a high latitude in the northern hemisphere. We used both dipteran and hymenopteran colour models and phylogenetically informed analyses to explore the chromatic component of community assembly. The species with cream-green flowers are very restricted in colour space models of both fly vision and bee vision and represent a distinct group that plays a very minor role in other communities. It is unlikely that such a community could form through random immigration from continental source pools. Our findings suggest that fly pollination has imposed a strong ecological filter on Macquarie Island, favouring floral colours that are rare in continental floras. This is one of the strongest demonstrations that plant-pollinator interactions play an important role in plant community assembly. Future work exploring colour choices by dipteran flower visitors would be valuable. [ABSTRACT FROM AUTHOR]

The two-pore cation channel TPC1 operates as a dimeric channel in animal and plant endomembranes. Each subunit consists of two homologous Shaker-like halves, with 12 transmembrane domains in total (S1-S6, S7-S12). In plants, TPC1 channels reside in the vacuolar membrane, and upon voltage stimulation, give rise to the well-known slow-activating SV currents., Here, we combined bioinformatics, structure modelling, site-directed mutagenesis, and in planta patch clamp studies to elucidate the molecular mechanisms of voltage-dependent channel gating in TPC1 in its native plant background., Structure-function analysis of the Arabidopsis TPC1 channel in planta confirmed that helix S10 operates as the major voltage-sensing site, with Glu450 and Glu478 identified as possible ion-pair partners for voltage-sensing Arg537. The contribution of helix S4 to voltage sensing was found to be negligible. Several conserved negative residues on the luminal site contribute to calcium binding, stabilizing the closed channel., During evolution of plant TPC1s from two separate Shaker-like domains, the voltage-sensing function in the N-terminal Shaker-unit (S1-S4) vanished. [ABSTRACT FROM AUTHOR]

Bamboos are one of the fastest growing plants on Earth, and are widely considered to have high ability to capture and sequester atmospheric carbon, and consequently to mitigate climate change. We tested this hypothesis by measuring carbon dioxide ( CO2) emissions from bamboo culms and comparing them with their biomass sequestration potential. We analysed diurnal effluxes from Bambusa vulgaris culm surface and gas mixtures inside hollow sections of various bamboos using gas chromatography. Corresponding variations in gas pressure inside the bamboo section and culm surface temperature were measured. SEM micrographs of rhizome and bud portions of bamboo culms were also recorded. We found very high CO2 effluxes from culm surface, nodes and buds of bamboos. Positive gas pressure and very high concentrations of CO2 were observed inside hollow sections of bamboos. The CO2 effluxes observed from bamboos were very high compared to their carbon sequestration potential. Our measurements suggest that bamboos are net emitters of CO2 during their lifespan. [ABSTRACT FROM AUTHOR]

Prescribed burning is an important management tool in many parts of the world. While natural fires generally occur during the driest and warmest period of the year, prescribed burning is often timed out-of-season, when there is higher soil moisture and lower biomass combustibility. However, fire season may influence seedling recruitment after fire, e.g. through the effect of seed hydration status on fire tolerance. In non-fire-prone temperate regions, anthropogenic fire may occur exclusively in periods outside the growing season with higher soil moisture, which may have negative consequences on seedling recruitment. Fire tolerance of moist and dry seeds of 16 temperate European herbaceous species belonging to four families was assessed using heat treatment of 100 °C for 5 min and subsequent germination trials. Moist seeds of Asteraceae, Poaceae and Brassicaceae had a predominantly negative reaction to the heat treatment, while those of Fabaceae tolerated it or germination was even enhanced. The reaction of dry seeds was completely different, with positive responses in three species of the Fabaceae and fire tolerance in species of other families. Our results point out that hydration status may significantly influence the post-fire germination of seeds. Dry seeds were found to tolerate high heat, while moist seeds were harmed in more than half of the species. This implies that if prescribed burning is applied in temperate grasslands of Europe, it should be timed to dry periods of the dormant season in order to protect seeds from negative effects of fire. [ABSTRACT FROM AUTHOR]

Fungal endophytes have been documented in almost all terrestrial plant groups. Although the endophyte infection syndrome in agronomic cultivars is well studied, relatively little work addresses questions of spatial ecology and fire effects on epichloae endophyte infection in native grasses, and none, to our knowledge, in sub- Saharan Africa. We sampled seven populations of the native Festuca costata Nees along the spline of the Drakensberg range in South Africa at several spatial scales, including both recently burned and unburned stands. We tested epichloae presence and prevalence with immunoblot assays, PCR and genetic sequencing. We found epichloae endophytes were present and prevalent (38-98% infection rates depending on location). Variation in infection rates occurred primarily among locations, but also among bunches. There was little evidence that endophyte infection rates varied with fire. Novel evidence of epichloae infection of a native Festuca in South Africa opens the door to several new research questions, from the phylogenetic relationship between epichloae of sub- Saharan Africa and other continents to the ecological advantages or disadvantages that endophytes confer upon their hosts, especially in a fire-prone ecosystem vulnerable to global environmental change. [ABSTRACT FROM AUTHOR]

Living plant neighbours, but also their dead aboveground remains ( i.e. litter), may individually exert negative or positive effects on plant recruitment. Although living plants and litter co-occur in most ecosystems, few studies have addressed their combined effects, and conclusions are ambivalent. Therefore, we examined the response in terms of seedling emergence and growth of herbaceous grassland and forest species to different litter types and amounts and the presence of competitors. We conducted a pot experiment testing the effects of litter type (grass, oak), litter amount (low, medium, high) and interspecific competition (presence or absence of four Festuca arundinacea individuals) on seedling emergence and biomass of four congeneric pairs of hemicryptophytes from two habitat types (woodland, grassland). Interactions between litter and competition were weak. Litter presence increased competitor biomass. It also had positive effects on seedling emergence at low litter amounts and negative effects at high litter amounts, while competition had no effect on seedling emergence. Seedling biomass was negatively affected by the presence of competitors, and this effect was stronger in combination with high amounts of litter. Litter affected seedling emergence while competition determined the biomass of the emerged individuals, both affecting early stages of seedling recruitment. High litter accumulation also reduced seedling biomass, but this effect seemed to be additive to competitor effects. This suggests that live and dead plant mass can affect species recruitment in natural systems, but the mechanisms by which they operate and their timing differ. [ABSTRACT FROM AUTHOR]