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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]