Higher Plants Research Articles

Agriculturally Improved and Semi-Natural Permanent Grasslands Provide Complementary Ecosystem Services in Swedish Boreal Landscapes

Permanent grasslands cover more than a third of European agricultural land and are important for a number of ecosystem services. Permanent grasslands used for agriculture are broadly separated into agriculturally improved and semi-natural grasslands. High cultural and natural values linked to semi-natural grasslands are well documented. However, in boreal and hemi-boreal agricultural landscapes, less information is available about the areal coverage of improved permanent grasslands and their role for ecosystem service provision and biodiversity. In Sweden, grasslands are administratively separated into semi-natural (i.e., land that cannot be ploughed) or arable (i.e., improved temporary or permanent grassland on land that can be ploughed). We used data from a large-scale environmental monitoring program to show that improved permanent grassland (i.e., permanent grasslands on arable fields) may be a previously unrecognised large area of the agricultural land use in Sweden. We show that improved permanent grasslands together with semi-natural grasslands are both comparable but also complementary providers of a range of ecosystem services (plant species richness, plant resources for pollinators and forage amount for livestock production). However, as expected, semi-natural grasslands with the highest-level AESs (special values) show high species richness values for vascular plants, plants indicating traditional semi-natural management conditions and red-listed species. Improved permanent grasslands on arable fields are likely an underestimated but integral part of the agricultural economy and ecological function in boreal landscapes that together with high nature value semi-natural grasslands provide a broad range of ecosystem services.

Plant collecting in São Tomé and Príncipe—collectors and their itineraries during the colonial period

The history of vascular plant collecting on the islands of São Tomé and Príncipe, from the earliest times up to the independence of the country in 1975 is provided, along with biographical information on all the collectors that could be traced, with notes on their itineraries, collecting localities, and collections. Aspects of the social environment prevalent in São Tomé and Príncipe at the time that historical collections were made are highlighted and contextualised to enable an improved understanding of connections between scientific-botanical endeavour, colonialism, and slavery on São Tomé and Príncipe.

Vegetational and Structural Features of Forest Clearings in Plitvice Lakes National Park

The impact of various ecological factors, biogeographical position and both former and current anthropogenic activity in Plitvice Lakes National Park greatly influenced the development of different habitat types, including forest clearings. Due to the insufficient knowledge of this habitat type, based primarily on general descriptions within the National Habitat Classification of the Republic of Croatia (NN 27/2021, NN 101/2022), this paper deals with presenting their vegetational and structural characteristics in the national park area. The following taxonomic keys were used to determine plant species: Tutin et al. (1964-1980), Pignatti (1982), Javorka and Csapody (1991) and Martinčič et al. (1999). Furthermore, scientific nomenclature of plant species was conducted using Flora Croatica Database (Nikolić 2012), while threat status was aligned by the Red Book of Vascular Flora of Croatia (Nikolić and Topić 2005). Also, protection level was adjusted according to the Regulation on strictly protected species (NN 144/2013, NN 73/2016). Spectrum of life forms and chorological types were aligned according to Pignatti (2005). Vegetation was studied in accordance with the principles of the Braun-Blanquet approach (Braun-Blanquet 1964). Together with the basic parameters of the selected plots, the research also included the collection of structural parameters of forest clearings according to Medak et al. (2023). Based on conducted research, a total of 98 plots of forest clearing habitats were established with a total of five different forest clearing communities. The largest number of forest clearing communities belonged to Salicetum capreae, followed by Eupatorietum cannabini, Atropetum bella-donae, Telekium speciosae and Rubetum idaei. A total of 257 species of vascular plants were identified in the area and classified into 60 families. The most represented family was Asteraceae, while the highest relative representation of life-forms belonged to hemicryptophytes (H). Furthermore, the most represented chorologycal type in the area was Eurasian (20.6%). The habitat type contained a total of 11 strictly protected (SZ), 6 nearly threatened (NT), 3 vulnerable (VU), 2 data-deficient (DD) and 4 endemic species. In addition, the largest number of plots had an anthropogenic origin, irregular type (shape), occupied a small area (less than 1000 m2) and were located along the edges of both forests and forest roads. The results of this paper represent the first vegetational and structural data of forest clearings in the national park area which contribute to an expansion of our knowledge and understanding of this habitat type, and form a starting point for the necessary future research.

Phenolic compounds weaken the impact of drought on soil enzyme activity in global wetlands.

Soil enzymes play a central role in carbon and nutrient cycling, and their activities can be affected by drought-induced oxygen exposure. However, a systematic global estimate of enzyme sensitivity to drought in wetlands is still lacking. Through a meta-analysis of 55 studies comprising 761 paired observations, this study found that phosphorus-related enzyme activity increased by 38% as result of drought in wetlands, while the majority of other soil enzyme activities remained stable. The expansion of vascular plants under long-term drought significantly promoted the accumulation of phenolic compounds. Using a 2-week incubation experiment with phenol supplementation, we found that phosphorus-related enzyme could tolerate higher biotoxicity of phenolic compounds than other enzymes. Moreover, a long-term (35 years) drainage experiment in a northern peatland in China confirmed that the increased phenolic concentration in surface layer resulting from a shift in vegetation composition inhibited the increase in enzyme activities caused by rising oxygen availability, except for phosphorus-related enzyme. Overall, these results demonstrate the complex and resilient nature of wetland ecosystems, with soil enzymes showing a high degree of adaptation to drought conditions. These new insights could help evaluate the impact of drought on future wetland ecosystem services and provide a theoretical foundation for the remediation of degraded wetlands.

Hexosamine biosynthesis and related pathways, protein N-glycosylation and O-GlcNAcylation: their interconnection and role in plants.

N-Acetylglucosamine (GlcNAc), a fundamental amino sugar moiety, is essential for protein glycosylation, glycolipid, GPI-anchor protein, and cell wall components. Uridine diphosphate-GlcNAc (UDP-GlcNAc), an active form of GlcNAc, is synthesized through the hexosamine biosynthesis pathway (HBP). Although HBP is highly conserved across organisms, the enzymes involved perform subtly distinct functions among microbes, mammals, and plants. A complete block of HBP normally causes lethality in any life form, reflecting the pivotal role of HBP in the normal growth and development of organisms. Although HBP is mainly composed of four biochemical reactions, HBP is exquisitely regulated to maintain the homeostasis of UDP-GlcNAc content. As HBP utilizes substrates including fructose-6-P, glutamine, acetyl-CoA, and UTP, endogenous nutrient/energy metabolites may be integrated to better suit internal growth and development, and external environmental stimuli. Although the genes encoding HBP enzymes are well characterized in microbes and mammals, they were less understood in higher plants in the past. As the HBP-related genes/enzymes have largely been characterized in higher plants in recent years, in this review we update the latest advances in the functions of the HBP-related genes in higher plants. In addition, HBP's salvage pathway and GlcNAc-mediated two major co- or post-translational modifications, N-glycosylation and O-GlcNAcylation, are also included in this review. Further knowledge on the function of HBP and its product conjugates, and the mechanisms underlying their response to deleterious environments might provide an alternative strategy for agricultural biofortification in the future.

Report of the General Committee: 29

SummaryDecisions of the General Committee are reported on proposals and requests in Report 74 of the Permanent Nomenclature Committee for Vascular Plants and on two older proposals: 2550 (Plagiomnium) and 2786 (Ipomoea). The General Committee has approved the list of institutional votes for the Nomenclature Section of the XX International Botanical Congress in Madrid.

Vascular plant, bryophyte, and lichen biodiversity of Agguttinni Territorial Park, Baffin Island, Nunavut, Canada: an annotated species checklist of a new Arctic protected area

Agguttinni Territorial Park is a large, newly established park on the east-central coast of Baffin Island in Nunavut, Canada. Previous knowledge of the plant and lichen biodiversity was limited and based mostly on collections made during the 1950 Baffin Island Expedition. We conducted a floristic inventory of the park in 2021 and re-examined previous collections. We recorded 141 species of vascular plants belonging to 25 families, 69 species of bryophytes in 27 families, and 93 species of lichens in 23 families. Most of the vascular plant and bryophyte species are new records for the park area, and some vascular plants, bryophytes, and lichens are newly reported for Baffin Island, Nunavut, or the Canadian Arctic or represent significant range extensions. Vascular plant species diversity varied greatly among localities, with inland valleys at the heads of fiords showing highest diversity and interior rocky barrens showing the lowest.

A new R package to parse plant species occurrence records into unique collection events efficiently reduces data redundancy

Biodiversity data aggregators, such as Global Biodiversity Information Facility (GBIF) suffer from inflation of the number of occurrence records when data from different databases are merged but not fully reconciled. The ParseGBIF workflow is designed to parse duplicate GBIF species occurrence records into unique collection events (gatherings) and to optimise the quality of the spatial data associated with them. ParseGBIF provides tools to verify and standardize species scientific names according to the World Checklist of Vascular Plants taxonomic backbone, and to parse duplicate records into unique ‘collection events’, in the process compiling the most informative spatial data, where more than one duplicate is available, and providing crude estimates of taxonomic and spatial data quality. When GBIF occurrence records for a medium-sized vascular plant family, the Myrtaceae, were processed by ParseGBIF, the average number of records useful for spatial analysis increased by 180%. ParseGBIF could therefore be valuable in the evaluation of species’ occurrences at the national scale in support for national biodiversity plans, identification of plant areas important for biodiversity, sample bias estimation to inform future sampling efforts, and to forecast species range shifts in response to global climate change.

Searching for mechanisms driving root pressure in Zea mays—a transcriptomic approach

While there are many theories and a variety of innovative datasets contributing to our understanding of the mechanism generating root pressure in vascular plants, we are still unable to produce a specific cellular mechanism for any species. To discover these mechanisms, we used RNA-Seq to explore differentially expressed genes in three different tissues between individual Zea mays plants expressing root pressure and those producing none. Working from the perspective that roots cells are utililizing a combination of osmotic exudation and hydraulic pressure mechanisms to generate positively-pressured flow of water into the xylem from the soil, we hypothesized that differential expression analysis would yield candidate genes coding for membrane transporters, ion channels, ATPases, and hormones with clear relevance to root pressure generation. In basal stem and coarse root tissue, we observed these classes of differentially expressed genes and more, including a strong cytoskeletal remodeling response. Fine roots displayed remarkably little differential expression relevant to root pressure, leading us to conclude that they either do not contribute to root pressure generation or are constitutively expressing root pressure mechanisms regardless of soil water content.

Survival and Development Strategies of Cyanobacteria through Akinete Formation and Germination in the Life Cycle

Eutrophic freshwater ecosystems are vulnerable to toxin-producing cyanobacteria growth or harmful algal blooms. Cyanobacteria belonging to the Nostocales order form akinetes that are similar to the seeds of vascular plants, which are resting cells surrounded by a thick membrane. They overwinter in sediment and germinate when conditions become favorable, eventually developing into vegetative cells and causing blooms. This review covers the cyanobacterial akinete of the Nostocales order and summarizes the environmental triggers and cellular responses involved in akinete germination and formation based on data from the literature. It also emphasizes the intimate and dynamic relationship that exists between the germination and formation of akinete in the annual life cycle of cyanobacteria. After comparing many published data, it is found that the tolerance ranges for factors affecting both akinete germination and formation do not differ significantly and are broadly consistent with the tolerance ranges for vegetative cell growth. However, the optimal range varies with different species and strains of cyanobacteria. The life cycle of cyanobacteria, as a result of akinete germination and formation, has a seasonal periodicity and spatial connectivity between the water column and the sediment. However, during the summer growing season, intimate coupling between akinete formation and germination can occur in the water column, and this can contribute to high population densities being maintained in the water column. During this time, shallow sediment could also provide suitable conditions for akinete germination, thereby contributing to the establishment of water column populations. The information summarized in this review is expected to help improve our shared understanding of the life cycle of the Nostocales cyanobacteria while also providing insights into the monitoring and management of harmful algal blooms.

Extinction risk predictions for the world's flowering plants to support their conservation.

More than 70% of all vascular plants lack conservation status assessments. We aimed to address this shortfall in knowledge of species extinction risk by using the World Checklist of Vascular Plants to generate the first comprehensive set of predictions for a large clade: angiosperms (flowering plants, c. 330 000 species). We used Bayesian Additive Regression Trees (BART) to predict the extinction risk of all angiosperms using predictors relating to range size, human footprint, climate, and evolutionary history and applied a novel approach to estimate uncertainty of individual species-level predictions. From our model predictions, we estimate 45.1% of angiosperm species are potentially threatened with a lower bound of 44.5% and upper bound of 45.7%. Our species-level predictions, with associated uncertainty estimates, do not replace full global, or regional Red List assessments, but can be used to prioritise predicted threatened species for full Red List assessment and fast-track predicted non-threatened species for Least Concern assessments. Our predictions and uncertainty estimates can also guide fieldwork, inform systematic conservation planning and support global plant conservation efforts and targets.

Rarities pattern of vascular plants in the high-altitude forests of Indian western Himalaya: Conservation implications

The assessment of plant rarity patterns and mapping of endemic species is a challenging task, however, this kind of assessment having great conservation significance. In the present study, a classification system of rarity, considering biogeographical, ecological and abundance of species was developed along with assessing the vegetation composition. Following systematic random approach of vegetation sampling, three altitude transects were sampled within each 100 m interval in three possible aspects (North-West, North-East and South-West) in the high-altitude forested zone (2000–3300 m asl) of Kedarnath Wildlife Sanctuary (KWS). The study identified a total of 295 plant species (191 genera and 70 families) in the studied region. Considering different attributes of rarity, 8- rarity groups were used for identification of rare and endemic plants. Altogether, most of the species exhibited wide geographical distribution an attribute of commonness, and few of these have narrow distributions due to habitat specificity. The lower altitudinal zone exhibited the maximum floristic diversity (184 spp.; 62.4 %), and minimum in the higher zone (134 spp.; 45.4 %). Tree species richness decreases, and its endemic subset increased along the altitudinal gradient due to remoteness, habitat heterogeneity, isolation of the areas and other environmental factors. A sharp decline was observed in the tree species richness from lower (33 spp.; 84.6 %) to higher altitude (8 spp.; 20.51 %). The species to genera ratio in the entire altitudinal range was 1.2 for trees and 1.6 for shrubs and herbs. Rarity analysis of these native and endemic species has highlighted conservation priorities at local and regional scale.

Arid agroecosystem plant diversity results from habitat-specific traditional management

In the arid landscapes of South Morocco's Saharan fringe, traditional agroecosystems stand out for their rich diversity of segetal vegetation. This study examines the segetal flora of these unique agroecosystems, investigating their richness, community characteristics and composition. We collected 155 relevés in fields located in the Guelmim province comprising three agroecosystem types: Oases, terraced and floodplain fields (faïd). We found 221 vascular plant species including seven regional endemics and one nationally very rare species. Using TWINSPAN, we identified three plant communities, each restricted to a specific agroecosystem type, displaying differences in species composition, floristic status, life-form and biogeographical spectra. Oasis vegetation had the highest overall number of species, terraced fields had the highest diversity, and therophytes were dominant across all communities, with faïds being the most therophyte-rich. The pan-Mediterranean chorotype dominated all three community types. Apophytes dominated, particularly in faïd and terraced fields, surpassing oasis fields rich in ruderals. We found that traditional cereal agroecosystems in southern Morocco harbor species-rich segetal plant communities created by habitat-based land-use systems. Our results highlight the significance of agricultural practices and local abiotic factors in shaping the agroecosystems, which are adapted to arid environments and sensitive to environmental and social changes.

Mosses and vascular plants show diverging diversity patterns along a latitudinal gradient in boreal bogs and fens

AbstractQuestionsThe latitudinal biodiversity gradient; i.e., the increase in biodiversity towards the equator, is one of the most prominent biodiversity patterns. Nevertheless, many questions remain to be answered about the influence of multiple environmental factors on the latitudinal biodiversity gradient, especially for mosses, and the functional diversity of mosses and vascular plants. This study aims at evaluating the influence of latitude, climate, environmental variables, and habitat types (bog vs fen) on taxonomic and functional diversity (α‐diversity and β‐diversity) and the composition of vascular plant and moss species.Location49° N to 55° N in Northwestern Quebec, Canada.TaxonMosses, vascular plants.MethodsWe used a database containing 376 phytosociological plots (400 m2) sampled in boreal peatlands located along a 600‐km latitudinal gradient. We evaluated changes in α‐diversity and β‐diversity in response to latitude, longitude, climate, and local abiotic variables for both taxonomic groups using linear mixed effect models. We evaluated the effects of these variables on taxonomic and functional composition using variance partitioning by redundancy analysis.ResultsMoss diversity increased with latitude, although the effects were masked by environmental variables, whereas vascular plant diversity decreased with latitude in fens and did not vary with latitude in bogs. We observed a decrease in taxonomic and functional uniqueness with latitude. Moss and vascular plant taxonomic and functional composition were primarily structured by contrasting local conditions in bogs and fens, whereas climatic variations along the latitudinal gradient played a secondary role.ConclusionsOur results highlight the contrasting biodiversity patterns in both peatland types and the importance of local habitat conditions in structuring vascular plant and moss diversity. These patterns varied depending on the diversity indicator used, as α‐ and β‐diversity and functional and taxonomic diversity were often decoupled. Future studies should therefore include more than one diversity indicator and consider the differences between ecosystems and taxon groups.

Ecological indicator values of understorey plants perform poorly to infer forest microclimate temperature

AbstractQuestionEcological indicator values (EIVs) reflect species‘ optimal conditions on an environmental gradient, such as temperature. Averaged over a community, they are used to quantify thermophilization stemming from climate change, i.e. the reshuffling of communities toward more warm‐adapted species. In forests, understorey plant communities do not keep up with global warming and accumulate a climatic debt. Although the causes are still debated, this thermal lag may be partly explained by forest microclimate buffering. For the first time, we test whether community means of EIVs are able to capture microclimate (here, under forest canopies) temperature across, or also within forests.Location157 forest plots across three French deciduous forests covering a large macroclimatic gradient.MethodsTo assess whether EIVs can be used to infer the mean and range of microclimate temperature in forests, we measured understorey air temperature for ca. 1 year (10 months) with sensors located 1 m above the ground. We surveyed bryophytes and vascular plants within 400‐m2 plots, and computed floristic temperature from ordinal‐scale EIVs (Ellenberg, Julve) and degree‐scale EIVs (ClimPlant, Bryophytes of Europe Traits) for both temperature and continentality, i.e. temperature annual range. Finally, we fitted linear models to assess whether EIVs could explain the mean and range of microclimate temperature in forests.ResultsVascular plant and bryophyte communities successfully reflected differences in mean annual temperatures across forests but largely failed to do so for microclimate variation within forests. Bryophytes did not perform better than vascular plants to infer microclimate conditions. The annual range of microclimate temperatures was poorly associated with ordinal‐scale EIVs for continentality but was positively correlated with degree‐scale EIVs for annual range within lowland forests, especially for vascular plant communities.ConclusionOverall, the capabilities of EIVs to infer microclimate was inconsistent. Refined EIVs for temperature are needed to capture forest microclimates experienced by understorey species.

Experimental warming and nitrogen deposition in clear‐cuts and forest edges: Assessing impacts on plant communities and tree seedling performance

AbstractQuestionsDo nitrogen deposition and climate warming affect tree seedlings and plant communities in different habitats? In these habitats, how do microenvironments, including soil properties and, when applicable, edge effects relate to plant performance?LocationThe University of British Columbia Malcolm Knapp Research Forest, Maple Ridge, British Columbia, Canada.MethodsWe assessed performance of Pseudotsuga menziesii (Mirb.) Franco, Thuja plicata Donn ex D. Don and Tsuga heterophylla (Raf.) Sarg. planted tree seedlings and associated vascular plant communities. Performance of tree seedlings (height) and under vascular plant communities (percent cover) were examined in an experiment with warming (open‐top chambers) and nitrogen deposition (ammonium nitrate applied at 10 kg N ha−1 year−1) treatments applied to subplots in six forest edges and six clear‐cuts (N = 298 total subplots).ResultsIn clear‐cuts, tree seedling height increased with experimental warming and differed among species, and vascular plant cover increased with warming. In clear‐cuts, species identity, not soil variables, was a strong predictor of height, and plant cover was negatively related to pH. In forest edges, edge position and some soil variables were related to height, but not plant cover. There were no interaction effects found between experimental nitrogen deposition and warming.ConclusionsOur results suggest that moderate warming can enhance tree seedling height and understorey vascular plant cover in clear‐cuts in Pacific Northwest coastal ecosystems, but low nitrogen deposition may not have an effect alone or synergistically with warming.

Different seasonal dynamics of contrasting aquatic plants and the consequences for the submerged macrophyte biodiversity

Global warming shifts climate zones to the north, resulting in changes in biodiversity. One of the species adaptation strategies to survive is to change their phenology. In temperate climate, most aquatic plants show their peak of biomass in summer. In our study, we hypothesised that the rare charophyte Lychnothamnus barbatus and the partially invasive vascular plant Myriophyllum spicatum may apply a different seasonality and cause a decrease in the biodiversity of submerged macrophytes. The object of our study was a mesotrophic temperate lake in Western Poland with abundant submerged vegetation, where macrophyte seasonality was studied from November 2015 to November 2019 (autumn, spring, summer). Altogether, 29 taxa of plants were recorded, including 13 species of charophytes (40 % of the Polish charophyte flora) but only four species co-dominated, two eutrophic vascular plants, Ceratophyllum demersum and M. spicatum, and two charophytes, the rare mesotrophic L. barbatus and common Nitellopsis obtusa. M. spicatum due to its expansiveness in the shallow littoral decreased biodiversity in the study lake. Moreover, C. demersum negatively affected the endangered L. barbatus by direct competition for habitats in the lake. L. barbatus and M. spicatum dominated in vegetation in autumn while the further two species co-dominated in summer. L. barbartus and M. spicatum seem to avoid high competition in summer, which proves a high adaptive potential with respect to climate warming. However, further study in other lakes is needed to verify the relevance of our findings in terms of the conservation of rare macrophyte species.

MiCOL6, MiCOL7A and MiCOL7B isolated from mango regulate flowering and stress response in transgenic Arabidopsis.

The CONSTANS/CONSTANS-Like (CO/COL) family has been shown to play important roles in flowering, stress tolerance, fruit development and ripening in higher plants. In this study, three COL genes, MiCOL6, MiCOL7A and MiCOL7B, which each contain only one CCT domain, were isolated from mango (Mangifera indica), and their functions were investigated. MiCOL7A and MiCOL7B were expressed mainly at 20 days after flowering (DAF), and all three genes were highly expressed during the flowering induction period. The expression levels of the three genes were affected by light conditions, but only MiCOL6 exhibited a clear circadian rhythm. Overexpression of MiCOL6 promoted earlier flowering, while overexpression of MiCOL7A or MiCOL7B delayed flowering compared to that in the control lines of Arabidopsis thaliana under long-day (LD) and short-day (SD) conditions. Overexpressing MiCOL6, MiCOL7A or MiCOL7B in transgenic plants increased superoxide dismutase (SOD) and proline levels, decreased malondialdehyde (MAD) levels, and improved survival under drought and salt stress. In addition, yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) analyses showed that the MiCOL6, MiCOL7A and MiCOL7B proteins interact with several stress- and flower-related proteins. This work demonstrates the functions of MiCOL6, MiCOL7A and MiCOL7B and provides a foundation for further research on the role of mango COL genes in flowering regulation and the abiotic stress response.

TaCRT3 Is a Positive Regulator of Resistance to Blumeria graminis f. sp. tritici in Wheat.

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most prevalent diseases of wheat worldwide and can lead to severe yield reductions. Identifying genes involved in powdery mildew resistance will be useful for disease resistance breeding and control. Calreticulin (CRT) is a member of multigene family widely found in higher plants and is associated with a variety of plant physiological functions and defense responses. However, the role of CRT in wheat resistance to powdery mildew remains unclear. TaCRT3 was identified from the proteomic sequence of an incompatible interaction between the wheat (Triticum aestivum) cultivar Xingmin 318 and the Bgt isolate E09. Following analysis of transient expression of the GFP-TaCRT3 fusion protein in Nicotiana benthamiana leaves, TaCRT3 was localized in the nucleus, cytoplasm, and cell membrane. Transcript expression levels of TaCRT3 were significantly upregulated in the wheat-Bgt incompatible interaction. More critically, knockdown of TaCRT3 using virus-induced gene silencing resulted in attenuated resistance to Bgt in wheat. Histological analysis showed a significant increase in Bgt development in TaCRT3-silenced plants, whereas the pathogen-related gene was significantly downregulated in TaCRT3-silenced leaves. In addition, overexpression of TaCRT3 in wheat enhanced the resistance to powdery mildew, the growth of Bgt was significantly inhibited, and the area of H2O2 near the infection site and the expression of defense-related genes of the salicylic acid pathway significantly increased. These findings imply that TaCRT3 may act as a disease resistance factor that positively regulates resistance to powdery mildew, during which SA signaling is probably activated.

N-fertilization and disturbance exert long-lasting complex legacies on subarctic ecosystems

Subarctic ecosystems are subjected to increasing nitrogen (N) enrichment and disturbances that induce particularly strong effects on plant communities when occurring in combination. There is little experimental evidence on the longevity of these effects. We applied N-fertilization (40 kg urea-N ha−1 year−1 for 4 years) and disturbance (removal of vegetation and organic soil layer on one occasion) in two plant communities in a subarctic forest-tundra ecotone in northern Finland. Within the first four years, N-fertilization and disturbance increased the share of deciduous dwarf shrubs and graminoids at the expense of evergreen dwarf shrubs. Individual treatments intensified the other’s effect resulting in the strongest increase in graminoids under combined N-fertilization and disturbance. The re-analysis of the plant communities 15 years after cessation of N-fertilization showed an even higher share of graminoids. 18 years after disturbance, the total vascular plant abundance was still substantially lower and the share of graminoids higher. At the same point, the plant community composition was the same under disturbance as under combined N-fertilization and disturbance, indicating that multiple perturbations no longer reinforced the other’s effect. Yet, complex interactions between N-fertilization and disturbance were still detected in the soil. We found higher organic N under disturbance and lower microbial N under combined N-fertilization and disturbance, which suggests a lower bioavailability of N sources for soil microorganisms. Our findings support that the effects of enhanced nutrients and disturbance on subarctic vegetation persist over decadal timescales. However, they also highlight the complexity of plant–soil interactions that drive subarctic ecosystem responses to multiple perturbations across varying timescales.