Ülo Niinemets

Estonian University of Life Sciences | EMU · Chair of Crop Science and Plant Biology

Heat stress induces secondary metabolic changes in plants, channeling photosynthetic carbon and energy, away from primary metabolic processes, including, growth. Use of ACC (1-aminocyclopropane-1-carboxylate) deaminase containing plant growth promoting bacteria (PGPB) in conferring heat resistance in plants and the role of PGPB, in altering net car...

Our power to predict the future relies on our knowledge of the past. Paleoproxies are a powerful tool for understanding environmental and ecological conditions and changes across different time periods. However, constructing a functioning paleoproxy requires a well-constrained and robustly tested model. This is challenging, especially if ecological...

Plant functional traits directly affect ecosystem functions. At the species level, trait combinations depend on trade-offs representing different ecological strategies, but at the community level trait combinations are expected to be decoupled from these trade-offs because different strategies can facilitate co-existence within communities. A key r...

The tundra is warming more rapidly than any other biome on Earth, and the potential ramifications are far-reaching because of global feedback effects between vegetation and climate. A better understanding of how environmental factors shape plant structure and function is crucial for predicting the consequences of environmental change for ecosystem...

The Amazon forest is the largest source of isoprene emissions, and the seasonal pattern of leaf-out phenology in this forest has been indicated as an important driver of seasonal variation in emissions. Still, it is unclear how emissions vary between different leaf phenological types in this forest. To evaluate the influence of leaf phenological ty...

Understanding the main ecological constraints on plants' adaptive strategies to tolerate multiple abiotic stresses is a central topic in plant ecology. We aimed to uncover such constraints by analysing how the interactions between climate, soil features and species functional traits co‐determine the distribution and diversity of stress tolerance st...

Domestication has dramatically increased crop size and biomass, reflecting the enhanced accumulation of photosynthates. However, we still lack solid empirical data on the impacts of domestication on photosynthetic rates at different light intensities and on leaf anatomy, and of the relationships of photosynthesis with aboveground biomass. In this s...

Cotyledons play an important role in early seedling establishment. However, relative to primary leaves, cotyledons tend to have a different investment-on-return strategy. To detect the potential differences in the mass (M) versus area (A) scaling relationships between cotyledons and primary leaves in different light environments, a total of 75 Acer...

Traditional leaf gas exchange experiments have focused on net CO 2 exchange ( A net ). Here, using California poplar ( Populus trichocarpa ), we coupled measurements of net oxygen production (NOP), isoprene emissions and δ ¹⁸ O in O 2 to traditional CO 2 /H 2 O gas exchange with chlorophyll fluorescence, and measured light, CO 2 and temperature res...

Trichomes are specialized epidermal outgrowths covering the aerial parts of most terrestrial plants. There is a large species variability in occurrence of different types of trichomes such that the molecular regulatory mechanism underlying the formation and the biological function of trichomes in most plant species remain unexplored. Here, we used...

Ozone (O 3 ) is one of the most harmful and widespread air pollutants, affecting crop yield and plant health worldwide. There is evidence that O 3 reduces the major limiting factor of photosynthesis, namely CO 2 mesophyll conductance ( g m ), but there is little quantitative information of O 3 ‐caused changes in key leaf anatomical traits and their...

Total leaf area per plant is an important measure of the photosynthetic capacity of an individual plant that together with plant density drives the canopy leaf area index, that is, the total leaf area per unit ground area. Because the total number of leaves per plant (or per shoot) varies among conspecifics and among mixed species communities, this...

Soil phosphorus (P) availability affects plant growth and distribution. However, it is still unknown how sex‐specific variation in functional traits affects plants’ P acquisition and soil P transformation. On wet sites, female poplars had a greater specific root length (SRL), and a higher diversity of arbuscular mycorrhizal fungi (AMF) and phosphat...

Phytophthora infestans is the causal agent of late blight in potato. The occurrence of P. infestans with both A1 and A2 mating types in the field may result in sexual reproduction and the generation of recombinant strains. Such strains with new combinations of traits can be highly aggressive, resistant to fungicides, and can make the disease diffic...

The share of overall photosynthetic limitation due to stomatal conductance (gs), mesophyll conductance (gm) and biochemistry depends on environmental conditions, but there is limited information on how the environmental responsiveness of photosynthesis varies among species with different heat thresholds. The study examined the photosynthetic respon...

[This corrects the article DOI: 10.1371/journal.pone.0277337.].

The vascular veins in photosynthetic leaves play an important role in transporting water and sugars throughout the plant body, and their venation pattern and vein density determine the hydraulic efficiency of the leaf. Likewise, stomatal density (SD) can influence photosynthetic gas exchange. However, the correlation between leaf vein density and S...

Urban ecosystems are formed by pronounced socio‐ecological gradients, which are distinct from other ecosystems and can simultaneously filter and promote taxa, ultimately affecting their interactions. However, the strength of the effect of filtering and facilitation across the different trophic levels could vary among biotic and abiotic factors. Her...

Urban biodiversity and ecosystem services depend on the quality, quantity, and connectivity of urban green areas (UGAs), which are crucial for enhancing urban livability and resilience. However, assessing these connectivity metrics in urban landscapes often suffers from outdated land cover classifications and insufficient spatial resolution. Spectr...

In cities, green areas are essential for biodiversity conservation, with land cover heterogeneity being a decisive factor. Yet, as heterogeneity increases for a given green area, the patch size of land covers automatically decreases, as the area available for individual species, especially habitat specialist species. This relationship, known as the...

Males and females of dioecious plants have sex‐specific adaptations to diverse habitats. The effects of inter‐ and intrasexual interactions in poplar plantations on composition, structure, and function of soil microbiota have not been explored in degraded areas. We conducted a series of greenhouse and field experiments to investigate how belowgroun...

Knowledge of a pathogen's genetic variability and population structure is of benefit to effective disease management. In this study, 193 isolates of Phytophthora infestans collected from three Estonian islands, were characterized over three years using SSRs marker data complemented by information on their mating type and resistance to metalaxyl. In...

Aim Trade‐offs among tolerances to different abiotic stressors limit polytolerance in woody plants. However, the general trait syndromes that underlie large‐scale tolerance patterns of woody plants remain controversial. Here, we tested if the leading trait dimensions that define the global spectrum of plant form and function capture the underlying...

Stomata are involved in transpiration and CO2 uptake by mediating gas exchange between internal plant tissues and the atmosphere. The capacity for gas exchange depends on stomatal density (SD), stomatal size, and pore dimensions. Most published work on stomatal quantification has assumed that stomatal distribution and stomatal density are spatially...

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, ever...

Industrial hemp cultivation restarted in Estonia in mid 2000s and the hemp cultivation area has increased very fast in recent years, but it is unknown to what extent hemp productivity can be curbed by widespread crop pests. Thus, the main aim of this study was to evaluate the presence and damage of hemp pests in northern field conditions. A field t...

Evolutionary radiations of woody taxa within arid environments were made possible by multiple trait innovations including deep roots and embolism‐resistant xylem, but little is known about how these traits have coevolved across the phylogeny of woody plants or how they jointly influence the distribution of species. We synthesized global trait and v...

Photosynthesis in both crops and natural vegetation allows light energy to be converted into chemical energy, and thus forms the foundation for almost all terrestrial trophic networks on Earth. The efficiency of photosynthetic energy conversion plays a crucial role in determining the portion of incident solar radiation that can be used to generate...

Little is known about how sex differences in root zone characteristics, such as contents of allelochemicals and soil microbial composition, mediate intra‐ and intersexual interactions in dioecious plants. We examined the processes and mechanisms of sex‐specific belowground interactions mediated by allelochemicals and soil microorganisms in Populus...

Leaf photosynthetic capacity (light-saturated net assimilation rate, AA) increases from bottom to top of plant canopies as the most prominent acclimation response to the conspicuous within-canopy gradients in light availability. Light-dependent variation in AA through plant canopies is associated with changes in key leaf structural (leaf dry mass p...

Fundamental axes of variation in plant traits result from trade-offs between costs and benefits of resource-use strategies at the leaf scale. However, it is unclear whether similar trade-offs propagate to the ecosystem level. Here, we test whether trait correlation patterns predicted by three well-known leaf- and plant-level coordination theories –...

The Estonia potato cultivar Ando has shown elevated field resistance to Phytophthora infestans, even after being widely grown for over 40 years. A comprehensive transcriptional analysis was performed using RNA-seq from plant leaf tissues to gain insight into the mechanisms activated for the defense after infection. Pathogen infection in Ando result...

Key message Stomatal area is proportional to the product of stomatal length and width with a proportionality coefficient exceeding π/4 (indicating a deviation from an elliptical shape) for four Magnoliaceae species. Abstract Stomatal size is an important factor affecting the photosynthetic and transpiration rates of vascular plants. To examine sto...

Rust infection results in stress volatile emissions, but due to the complexity of host-pathogen interaction and variations in innate defense and capacity to induce defense, biochemical responses can vary among host species. Fungal-dependent modifications in volatile emissions have been well documented in numerous host species, but how emission resp...

Volatile organic compounds (VOCs) play key roles in plant abiotic and biotic stress resistance, but even for widespread crops, there is limited information on variations in the magnitude and composition of constitutive VOC emissions among cultivars with varying stress resistance. The foliage VOC emissions from nine local and commercial potato culti...

Australia’s distinctive biogeography means that it is sometimes considered an ecologically unique continent with biological and abiotic features that are not comparable to those observed in the rest of the world. This leaves some researchers unclear as to whether findings from Australia apply to systems elsewhere (or vice-versa), which has conseque...

Aim Theoretical, experimental and observational studies have shown that biodiversity–ecosystem functioning (BEF) relationships are influenced by functional community structure through two mutually non‐exclusive mechanisms: (1) the dominance effect (which relates to the traits of the dominant species); and (2) the niche partitioning effect [which re...

Desiccation-rehydration studies in cryptogams constitute an important tool to understand the relation of key physiological traits with species stress tolerance and environmental adaptability. Real-time monitoring of responses has been limited by the design of commercial or custom measuring cuvettes and difficulties in experimental manipulation. We...

As Earth's climate has varied strongly through geological time, studying the impacts of past climate change on biodiversity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in biodiversity. Here, we assessed the influence of Quaternary climate change on spatial dissimila...

Plant microbiota can greatly impact plant growth, defense, and health in different environments. Thus, it might be evolutionarily beneficial for plants to be able to control processes related to microbiota assembly. Dioecious plant species display sexual dimorphism in morphology, physiology, and immunity. These differences imply that male and femal...

Climate change enhances the frequency of heatwaves that negatively affect photosynthesis and can alter constitutive volatile emissions and elicit emissions of stress volatiles, but how pre-exposure to mildly warmer temperatures affects plant physiological responses to subsequent severe heat episodes remains unclear, especially for aromatic plants w...

Biomagnetic monitoring increasingly is applied to assess particulate matter (PM) concentrations, mainly using plant leaves sampled in small geographical area and from a limited number of species. Here, the potential of magnetic analysis of urban tree trunk bark to discriminate between PM exposure levels was evaluated and bark magnetic variation was...

Urban ecosystems are associated with socio-ecological conditions that can filter and promote taxa. However, the strength of the effect of ecological filtering on biodiversity could vary among biotic and abiotic factors. Here, we investigate the effects of habitat amount, temperature, and host-enemy biotic interactions in shaping communities of cavi...

Rust infection results in decreases in photosynthesis and stress volatile emissions, but how these changes vary among host species has not been studied. We demonstrated the impact of the obligate biotrophic fungus, Puccinia coronata f. sp. avenae, on foliage physiological processes is stronger in the primary host, Avena sativa (cultivated oat), tha...

Plants are frequently exposed to heat stress as a result of global warming. Heat stress leads to a series of physiological responses including stress volatile elicitation, but how heat stress-induced volatile cues affect the behavior of herbivores is poorly understood. In this study, the polyphagous herbivore Spodoptera litura (tobacco cutworm, TCW...

Stomatal density (SD) is important to photosynthetic rates. However, it is time-consuming to measure SD. Here, we provide a method for estimating SD based on the scaling relationship between SD and mean nearest neighbour distance (MNND) of sampled stomatal centres. 397 leaves from eight Magnoliaceae species were used for this study. For each leaf,...

Fundamental axes of variation in plant traits result from trade-offs between costs and benefits of resource-use strategies at the leaf scale. However, it is unclear whether trade-offs and optimality principles in functional traits of leaves are conserved at the ecosystem level. We tested three well-known leaf- and plant-level coordination theories...

Plants have diverse leaf shapes that have evolved to adapt to the environments they have experienced over their evolutionary history. Leaf shape and leaf size can greatly influence the growth rate, competitive ability, and productivity of plants. However, researchers have long struggled to decide how to properly quantify the complexity of leaf shap...

Here we provide the ‘Global Spectrum of Plant Form and Function Dataset’, containing species mean values for six vascular plant traits. Together, these traits –plant height, stem specific density, leaf area, leaf mass per area, leaf nitrogen content per dry mass, and diaspore (seed or spore) mass – define the primary axes of variation in plant form...