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Following a request from the European Food Safety Authority, the Panel on Plant Protection Products and their Residues developed an opinion on the science to support the development of a risk assessment scheme of plant (crop) protection products on non‐target terrestrial plants (NTTPs). This scientific opinion is largely a literature review on the most up‐to‐date knowledge of factors influencing phytotoxicity testing and risk assessment of NTTPs. Specific protection goals (SPGs) were defined for off‐field, in‐field and endangered species. SPGs are closely linked to ecosystem services and functions, and include maintaining provision of water regulation, food web support, aesthetic values, genetic resources and biodiversity. Gaps were identified in standard guidelines currently used in lower tier testing (tier I/II). In these guidelines, tests are conducted at the seedling/juvenile stage using mostly annual crops, and effects are recorded at the juvenile/vegetative stage under greenhouse conditions with plants grown individually or in monoculture. Endpoints measured do not include the overall effect on the whole life cycle (germinating seeds, seedling, juvenile stages, flowering, and seed production and germinability). It is also noted that it is unknown whether the following groups of organisms are covered by the plant risk assessment as it is carried out now: ferns, mosses, liverworts, hornworts, horsetails, lichens or woody species. In terms of exposure, droplet drift is considered to be the most important factor for off‐field emissions to non‐target areas. Models are available to calculate loadings from spray drift. Higher tier assessment is not required if the risk based on the tier II level can be managed by risk mitigation measures. When required, higher tier tests should be conducted under more realistic conditions. They may include additional laboratory/greenhouse tests (e.g. to measure reproductive endpoints or species interactions), microcosms or field experiments with experimentally or already established species. Other issues were considered, including exposure to mixtures, adjuvants, co‐formulants and metabolites. Recommendations for the improvement of current guidelines and the elaboration of new guidelines and risk assessment schemes are provided.

Plants store large amounts of non-structural carbohydrates (NSC). While multiple functions of NSC have long been recognized, the interpretation of NSC seasonal dynamics is often based on the idea that stored NSC is a reservoir of carbon that fluctuates depending on the balance between supply via photosynthesis and demand for growth and respiration (the source–sink dynamics concept). Consequently, relatively high NSC concentrations in some plants have been interpreted to reflect excess supply relative to demand. An alternative view, however, is that NSC accumulation reflects the relatively high NSC levels required for plant survival; an important issue that remains highly controversial. Here, we assembled a new global database to examine broad patterns of seasonal NSC variation across organs (leaves, stems, and belowground), plant functional types (coniferous, drought-deciduous angiosperms, winter deciduous angiosperms, evergreen angiosperms, and herbaceous) and biomes (boreal, temperate, Mediterranean, and tropical). We compiled data from 121 studies, including seasonal measurements for 177 species under natural conditions. Our results showed that, on average, NSC account for ~10% of dry plant biomass and are highest in leaves and lowest in stems, whereas belowground organs show intermediate concentrations. Total NSC, starch, and soluble sugars (SS) varied seasonally, with a strong depletion of starch during the growing season and a general increase during winter months, particularly in boreal and temperate biomes. Across functional types, NSC concentrations were highest and most variable in herbaceous species and in conifer needles. Conifers showed the lowest stem and belowground NSC concentrations. Minimum NSC values were relatively high (46% of seasonal maximums on average for total NSC) and, in contrast to average values, were similar among biomes and functional types. Overall, although starch depletion was relatively common, seasonal depletion of total NSC or SS was rare. These results are consistent with a dual view of NSC function: whereas starch acts mostly as a reservoir for future use, soluble sugars perform immediate functions (e.g., osmoregulation) and are kept above some critical threshold. If confirmed, this dual function of NSC will have important implications for the way we understand and model plant carbon allocation and survival under stress.

Microplastic pollution is a largely unexplored yet pervasive environmental problem, in terrestrial environments, including impacts on plants and food crops. Plant growth and function are most often negatively impacted by plastic exposure, but these pollutants can also stimulate plant processes such as root growth and there is a tentative suggestion that monocotyledonous may be less sensitive to microplastics than dicotyledonous plants. Toxic effects include reduced plant biomass, chlorophyll content, photosynthesis, and changes to antioxidants, metabolites, and nutrients, with stimulatory effects often found at lower concentrations of exposure. There is strong evidence that roots can directly uptake and translocate plastic particles at 1 µm and under in size. Indirect effects include interactions of microplastics with other pollutants, soil properties, and soil organisms. These findings have potentially wide-ranging implications for terrestrial ecosystem function and human health. Future research should further elucidate the mechanisms of plant microplastic toxicity at realistic concentrations. This short review highlights the significance of microplastics in the terrestrial environment, where they can occur at higher concentrations than in the aquatic environment, with likely impacts on important food crop plants. The significance of these findings for human and ecosystem health remains to be elucidated and we make four recommendations to the scientific community for improved future experimentation.

• Background New roles for flavonoids, as developmental regulators and/or signalling molecules, have recently been proposed in eukaryotic cells exposed to a wide range of environmental stimuli. In plants, these functions are actually restricted to flavonols, the ancient and widespread class of flavonoids. In mosses and liverworts, the whole set of genes for flavonol biosynthesis - CHS, CHI, F3H, FLS and F3'H - has been detected. The flavonol branch pathway has remained intact for millions of years, and is almost exclusively involved in the responses of plants to a wide array of stressful agents, despite the fact that evolution of flavonoid metabolism has produced > 10 000 structures. • Scope Here the emerging functional roles of flavonoids in the responses of present-day plants to different stresses are discussed based on early, authoritative views of their primary functions during the colonization of land by plants. Flavonols are not as efficient as other secondary metabolites in absorbing wavelengths in the 290-320 nm spectral region, but display the greatest potential to keep stress-induced changes in cellular reactive oxygen species homeostasis under control, and to regulate the development of individual organs and the whole plant. Very low flavonol concentrations, as probably occurred in early terrestrial plants, may fully accomplish these regulatory functions. • Conclusions During the last two decades the routine use of genomic, chromatography/mass spectrometry and fluorescence microimaging techniques has provided new insights into the regulation of flavonol metabolism as well as on the inter- and intracellular distribution of stress-responsive flavonols. These findings offer new evidence on how flavonols may have performed a wide array of functional roles during the colonization of land by plants. In our opinion this ancient flavonoid class is still playing the same old and robust roles in presentday plants.

Nitrogen (N) and phosphorus (P) are essential components of the basic cell structure of plants. In particular, leaf N and P concentrations and their stoichiometric relationship largely determine the photosynthesis, growth, reproduction, and ecophysiological processes of plants. As important leaf functional traits, leaf N and P concentrations and their stoichiometric relationship play vital roles in indicating plant nutrient‐use strategies and their evolution in terrestrial ecosystems. They also influence physiological and ecological processes in leaves (e.g., growth rate and energy metabolism) and productivity (e.g., net primary production and net ecosystem production) at ecosystem level. However, the lack of a comprehensive data set containing paired leaf N and P concentration records has distinctly limited research on nutrient stoichiometry and leaf functional traits. Here, we provide a global database of paired records of leaf N and P concentrations. A total of 11,354 individual records were acquired spanning 1,291 sites worldwide, including 201 families, 1,265 genera, and 3,227 species. The records span a latitudinal range of 45.28 °S to 68.35 °N and a longitudinal range of 155.5 °W to 168.0 °E. The variables provided for each individual record are (1) geographical location (longitude, latitude, and altitude); (2) matched leaf N and P concentrations and N:P ratio; (3) taxonomic information (family, genera, and species); (4) life form (angiosperm/gymnosperm, monocotyledonous/dicotyledonous and woody plants/herbaceous plants; note that woody plants were further divided into coniferous, deciduous broad‐leaved, and evergreen broad‐leaved woody species and that herbaceous plants were further divided into annual and perennial species); (5) mean annual temperature (MAT) and mean annual precipitation (MAP); and (6) soil N and P concentrations and pH value in some records. To date, this database is the world's largest database of paired leaf N and P concentrations, which contains matched information of geographical location, environmental factors, and taxa. We believe that the database will play a fundamental and crucial part of ecological stoichiometric studies. There are no copyright restrictions. When using this database, we kindly request that you cite this article, respecting all the authors’ hard work during sample collection and data compilation.

Nuclear power reactors are operating in 31 countries around the world. Along with reactor operations, activities like mining, fuel fabrication, fuel reprocessing and military operations are the major contributors to the nuclear waste. The presence of a large number of fission products along with multiple oxidation state long-lived radionuclides such as neptunium ( 237 Np), plutonium ( 239 Pu), americium ( 241/243 Am) and curium ( 245 Cm) make the waste streams a potential radiological threat to the environment. Commonly high concentrations of cesium ( 137 Cs) and strontium ( 90 Sr) are found in a nuclear waste. These radionuclides are capable enough to produce potential health threat due to their long half-lives and effortless translocation into the human body. Besides the radionuclides, heavy metal contamination is also a serious issue. Heavy metals occur naturally in the earth crust and in low concentration, are also essential for the metabolism of living beings. Bioaccumulation of these heavy metals causes hazardous effects. These pollutants enter the human body directly via contaminated drinking water or through the food chain. This issue has drawn the attention of scientists throughout the world to device eco-friendly treatments to remediate the soil and water resources. Various physical and chemical treatments are being applied to clean the waste, but these techniques are quite expensive, complicated and comprise various side effects. One of the promising techniques, which has been pursued vigorously to overcome these demerits, is phytoremediation. The process is very effective, eco-friendly, easy and affordable. This technique utilizes the plants and its associated microbes to decontaminate the low and moderately contaminated sites efficiently. Many plant species are successfully used for remediation of contaminated soil and water systems. Remediation of these systems turns into a serious problem due to various anthropogenic activities that have significantly raised the amount of heavy metals and radionuclides in it. Also, these activities are continuously increasing the area of the contaminated sites. In this context, an attempt has been made to review different modes of the phytoremediation and various terrestrial and aquatic plants which are being used to remediate the heavy metals and radionuclide-contaminated soil and aquatic systems. Natural and synthetic enhancers, those hasten the process of metal adsorption/absorption by plants, are also discussed. The article includes 216 references.

Ultraviolet-B radiation (UV-B, 280-315 nm) is an important environmental signal that regulates growth and development in plants. Two dose-dependent UV-B response pathways were described in plants: a specific one, mediated by UVR8 (the specific UV-B receptor) and an unspecific one, activated by the oxidative damage produced by radiation. The constitutively expressed receptor appears inactive as a dimer, with the two monomers dissociating upon UV-B irradiation. The monomer then interacts with COP1, an ubiquitin ligase, hindering its ability to poly-ubiquitinate transcriptional factor HY5, thus averting its degradation and activating the photomorphogenic response. HY5 induces the synthesis of proteins RUP1 and RUP2, which interact with UVR8, releasing COP1, and inducing the re-dimerization of UVR8. This mechanism has been thoroughly characterized in Arabidopsis, where studies have demonstrated that the UVR8 receptor is key in UV-B response. Although Arabidopsis importance as a model plant many mechanisms described in this specie differ in other plants. In this paper, we review the latest information regarding UV-B response mediated by UVR8 in different species, focusing on the differences reported compared to Arabidopsis. For instance, UVR8 is not only induced by UV-B but also by other agents that are expressed differentially in diverse tissues. Also, in some of the species analyzed, proteins with low homology to RUP1 and RUP2 were detected. We also discuss how UVR8 is involved in other developmental and stress processes unrelated to UV-B. We conclude that the receptor is highly versatile, showing differences among species.

1. Dispersal via animals (zoochory) is a primary mechanism for seed exchange between habitat patches. Recent studies have established that many plant species can survive waterbird gut passage. To quantify the patterns and consequences of waterbird-mediated dispersal, information on ingestion and gut passage must be combined with bird movement data. Such analysis has recently revealed seed dispersal kernels by migrating waterbirds. However, since many waterbird populations are largely resident, and migrating populations spend only a minor part of the main dispersal season (autumn—winter) on active migration, daily regional-scale movements probably cause more frequent dispersal. 2. We synthesized high-resolution empirical data on landscape-scale movements and seed gut passage times in a key disperser species, the mallard (Anas platyrhynchos), using a spatially explicit, mechanistic model to quantify dispersal distributions resulting from daily autumn-winter movements. We evaluated how landscape composition and seed traits affect these dispersal patterns. 3. The model indicates that mallards generate highly clumped seed deposition patterns, dispersing seeds primarily between core areas used for foraging and resting. Approximately 34% of all dispersed seeds are transported to communal roost areas, which may function as reservoirs for mallarddispersed species, and 7% are transported between foraging areas. Landscape-dependent movement patterns strongly affect the dispersal distributions, resulting in multi-modal dispersal kernels, with dispersal distances increasing with fragmentation of freshwater foraging habitat. Seed size-related gut retention times determine the proportion of seeds being dispersed away from the ingestion area, with larger seeds (20 mm³) having a 8—10% higher potential for long-distance dispersal than smaller seeds (0.2 mm³), if surviving gut passage. However, twice as many small seeds will finally accomplish long-distance dispersal due to their higher gut passage survival. 4. Synthesis. Firstly, this study reveals how seed dispersal patterns resulting from daily waterfowl movements are shaped by landscape-dependent differences in movement patterns. Secondly, seed survival appears more important than retention time in determining the scale of long-distance dispersal by non-migrating mallards. We conclude that the frequent flights of staging waterbirds result in directed dispersal over distances inversely related to wetland availability, indicating that they maintain landscape connectivity across a range from wet to increasingly dry landscapes.

Summary Terrestrial plants create roughly 84 Tmol biogenic silicon (BSi) each year. This substantial uptake of dissolved silicon (DSi) by land plants represents an important, yet often overlooked, pathway of Si on the global scale. Agricultural crops account for ~35% of BSi created by land plants globally due to a combination of large biomass and relatively high Si concentrations in the tissue of many crops. In this review, we investigate the global importance of terrestrial BSi fixation by agricultural crops. Using annual data from 1961 to 2012 of the 10 most important crops (ranked by mass produced globally), we quantify how agriculture has altered the amount of BSi created on land. Over this time period, average annual BSi production by the top 10 crops tripled globally, increasing by an additional 39 Gmol Si each year. We refer to this BSi in agricultural crops as human‐appropriated biogenic Si (HABSi). Based on projected increases in human populations and land cover change, HABSi is projected to increase by 22–35% by 2050. Human agricultural practices are increasing the size of relatively labile plant BSi pool on land. Considering its bioavailable nature, we suggest that increasing plant BSi on land has the capacity to alter Si availability in downstream receiving waters, although this depends on the fate of harvesting and threshing losses, which varies substantially across the globe. We highlight similarities between the N, P and Si cycles in agricultural settings, such as the often unidirectional flow of Si away from croplands (similar to N) and soil BSi depletion (similar to P). We then address how changing human diets will continue to alter plant BSi cycling in future decades. Lay Summary

Bioactive C17 and C18 acetylenic oxylipins have shown to contribute to the cytotoxic, anti-inflammatory, and potential anticancer properties of terrestrial plants. These acetylenic oxylipins are widely distributed in plants belonging to the families Apiaceae, Araliaceae, and Asteraceae, and have shown to induce cell cycle arrest and/or apoptosis of cancer cells in vitro and to exert a chemopreventive effect on cancer development in vivo. The triple bond functionality of these oxylipins transform them into highly alkylating compounds being reactive to proteins and other biomolecules. This enables them to induce the formation of anti-inflammatory and cytoprotective phase 2 enzymes via activation of the Keap1–Nrf2 signaling pathway, inhibition of proinflammatory peptides and proteins, and/or induction of endoplasmic reticulum stress, which, to some extent, may explain their chemopreventive effects. In addition, these acetylenic oxylipins have shown to act as ligands for the nuclear receptor PPARγ, which play a central role in growth, differentiation, and apoptosis of cancer cells. Bioactive C17 and C18 acetylenic oxylipins appear, therefore, to constitute a group of promising lead compounds for the development of anticancer drugs. In this review, the cytotoxic, anti-inflammatory and anticancer effects of C17 and C18 acetylenic oxylipins from terrestrial plants are presented and their possible mechanisms of action and structural requirements for optimal cytotoxicity are discussed.