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Mechanistic Modeling Reveals Adaptive Photosynthetic Strategies of Pontederia crassipes: Implications for Aquatic Plant Physiology and Invasion Dynamics
The invasive aquatic macrophyte Pontederia crassipes (water hyacinth) exhibits exceptional adaptability across a wide range of light environments, yet the mechanistic basis of its photosynthetic plasticity under both high- and low-light stress remains poorly resolved. This study integrated chlorophyll fluorescence and gas-exchange analyses to evaluate three photosynthetic models—rectangular hyperbola (RH), non-rectangular hyperbola (NRH), and the Ye mechanistic model—in capturing light-response dynamics in P. crassipes. The Ye model provided superior accuracy (R2 > 0.996) in simulating the net photosynthetic rate (Pn) and electron transport rate (J), outperforming empirical models that overestimated Pnmax by 36–46% and Jmax by 1.5–24.7% and failed to predict saturation light intensity. Mechanistic analysis revealed that P. crassipes maintains high photosynthetic efficiency in low light (LUEmax = 0.030 mol mol−1 at 200 µmol photons m−2 s−1) and robust photoprotection under strong light (NPQmax = 1.375, PSII efficiency decline), supported by a large photosynthetic pigment pool (9.46 × 1016 molecules m−2) and high eigen-absorption cross-section (1.91 × 10−21 m2). Unlike terrestrial plants, its floating leaves experience enhanced irradiance due to water-surface reflection and are decoupled from water limitation via submerged root uptake, enabling flexible stomatal and energy regulation. Distinct thresholds for carboxylation efficiency (CEmax = 0.085 mol m−2 s−1) and water-use efficiency (WUEi-max = 45.91 μmol mol−1 and WUEinst = 1.96 μmol mmol−1) highlighted its flexible energy management strategies. These results establish the Ye model as a reliable tool for characterizing aquatic photosynthesis and reveal how P. crassipes balances light harvesting and dissipation to thrive in fluctuating environments. These resulting insights have implications for both understanding invasiveness and managing eutrophic aquatic systems.
Addressing the long-standing limitations of double exponential and non-rectangular hyperbolic models in quantifying light-response of electron transport rates in different photosynthetic organisms under various conditions
The models used to describe the light response of electron transport rate in photosynthesis play a crucial role in determining two key parameters i.e., the maximum electron transport rate (Jmax) and the saturation light intensity (Isat). However, not all models accurately fitJ–Icurves, and determine the values ofJmaxandIsat. Here, three models, namely the double exponential (DE) model, the non-rectangular hyperbolic (NRH) model, and a mechanistic model developed by one of the coauthors (Z-P Ye) and his coworkers (referred to as the mechanistic model), were compared in terms of their ability to fitJ–Icurves and estimateJmaxandIsat. Here, we apply these three models to a series of previously collected Chlafluorescence data from seven photosynthetic organisms, grown under different conditions. Our results show that the mechanistic model performed well in describing theJ–Icurves, regardless of whether photoinhibition/dynamic down-regulation of photosystem II (PSII) occurs. Moreover, bothJmaxandIsatestimated by this model are in very good agreement with the measured data. On the contrary, although the DE model simulates quite well theJ–Icurve for the species studied, it significantly overestimates both theJmaxofAmaranthus hypochondriacusand theIsatofMicrocystis aeruginosagrown under NH4+-N supply. More importantly, the light intensity required to achieve the potential maximum ofJ(Js) estimated by this model exceeds the unexpected high value of 105μmol photons m−2s−1forTriticum aestivumandA. hypochondriacus. The NRH model fails to characterize theJ-Icurves with dynamic down-regulation/photoinhibition forAbies alba,Oryza sativaandM. aeruginosa. In addition, this model also significantly overestimates the values ofJmaxforT. aestivumat 21% O2andA. hypochondriacusgrown under normal condition, and significantly underestimates the values ofJmaxforM. aeruginosagrown under NO3–N supply. Our study provides evidence that the ‘mechanistic model’ is much more suitable than both the DE and NRH models in fitting theJ–Icurves and in estimating the photosynthetic parameters. This is a powerful tool for studying light harvesting properties and the dynamic down-regulation of PSII/photoinhibition.
Foliar N Content Parallels Increasing Aridity in a Mediterranean‐Saharan Transition Zone: Evidence From Regional and Global Trends
ABSTRACTAimWarm deserts are characterised by water shortages and high temperature extremes. A commonly reported adaptive strategy in such environments is maximisation of photosynthetic capacity, which allows plants to achieve positive carbon budgets by taking advantage of short periods of water availability and non‐inhibitory temperatures. Considering the well‐supported interspecific covariation between photosynthetic capacity and leaf N concentration, we tested the hypothesis that environmental aridity is related to an elevated leaf nitrogen content.Location53 locations in the transitional zone spanning the Mediterranean and the Sahara Desert in Morocco. The mean maximal temperature (Tmax) within the area varied between 35.7°C and 43.5°C, and the mean annual precipitation (MAP) was between 12 and 246 mm.Taxon225 vascular species representative of local vegetation.MethodsLeaf samples were collected along a regional aridity gradient and preserved in herbarium presses. The leaf mass per area (LMA) and N concentrations expressed on leaf mass (Nmass) and area (Narea) basis were determined. We also obtained LMA and Nmass values for 6711 species from a worldwide database for comparative analysis.ResultsSignificant increases in mean LMA, Nmass and Narea accompanied the increase in Tmax and the decrease in MAP in woody species and in non‐graminoid herbs, but not in graminoids. Considering the overall aridity of our sampling area, we compared the Nmass values of Moroccan plants with those from a worldwide database. We found that at a common LMA, the Moroccan plants showed on average elevated Nmass relative to global values.Main ConclusionsThese two lines of evidence: regional gradient and global comparison confirm that hot deserts select for high leaf N content. This result suggests the direction of natural selection that will accompany future climate warming and habitat aridification.
Limitations of the Farquhar–von Caemmerer–Berry Model in Estimating the Maximum Electron Transport Rate: Evidence from Four C3 Species
The study evaluates the accuracy of two FvCB model sub-models (I and II) in estimating the maximum electron transport rate for CO2 assimilation (JA-max) by comparing estimated values with observed maximum electron transport rates (Jf-max) in four C3 species: Triticum aestivum L., Silphium perfoliatum L., Lolium perenne L., and Trifolium pratense L. Significant discrepancies were found between JA-max estimates from sub-model I and observed Jf-max values for T. aestivum, S. perfoliatum, and T. pratense (p < 0.05), with sub-model I overestimating JA-max for T. aestivum. Sub-model II consistently produced higher JA-max estimates than sub-model I. This study highlights limitations in the FvCB sub-models, particularly their tendency to overestimate JA-max when accounting for electron consumption by photorespiration (JO), nitrate reduction (JNit), and the Mehler reaction (JMAP). An alternative empirical model provided more accurate Jf-max estimates, suggesting the need for improved approaches to model photosynthetic electron transport. These findings have important implications for crop yield prediction, ecological modeling, and climate change adaptation strategies, emphasizing the need for more accurate estimation methods in plant physiology research.
Adaptive significance of age- and light-related variation in needle structure, photochemistry, and pigments in evergreen coniferous trees
Investigation on absorption cross-section of photosynthetic pigment molecules based on a mechanistic model of the photosynthetic electron flow-light response in C3, C4 species and cyanobacteria grown under various conditions
Investigation on intrinsic properties of photosynthetic pigment molecules participating in solar energy absorption and excitation, especially their eigen-absorption cross-section (σik) and effective absorption cross-section (σ′ik), is important to understand photosynthesis. Here, we present the development and application of a new method to determine these parameters, based on a mechanistic model of the photosynthetic electron flow-light response. The analysis with our method of a series of previously collected chlorophyll a fluorescence data shows that the absorption cross-section of photosynthetic pigment molecules has different values of approximately 10−21 m2, for several photosynthetic organisms grown under various conditions: (1) the conifer Abies alba Mill., grown under high light or low light; (2) Taxus baccata L., grown under fertilization or non-fertilization conditions; (3) Glycine max L. (Merr.), grown under a CO2 concentration of 400 or 600 μmol CO2 mol−1 in a leaf chamber under shaded conditions; (4) Zea mays L., at temperatures of 30°C or 35°C in a leaf chamber; (5) Osmanthus fragrans Loureiro, with shaded-leaf or sun-leaf; and (6) the cyanobacterium Microcystis aeruginosa FACHB905, grown under two different nitrogen supplies. Our results show that σik has the same order of magnitude (approximately 10−21 m2), and σ′ik for these species decreases with increasing light intensity, demonstrating the operation of a key regulatory mechanism to reduce solar absorption and avoid high light damage. Moreover, compared with other approaches, both σik and σ′ik can be more easily estimated by our method, even under various growth conditions (e.g., different light environment; different CO2, NO2, O2, and O3 concentrations; air temperatures; or water stress), regardless of the type of the sample (e.g., dilute or concentrated cell suspensions or leaves). Our results also show that CO2 concentration and temperature have little effect on σik values for G. max and Z. mays. Consequently, our approach provides a powerful tool to investigate light energy absorption of photosynthetic pigment molecules and gives us new information on how plants and cyanobacteria modify their light-harvesting properties under different stress conditions.
Ex situ germination of European acorns: data from 93 batches of 12 Quercus species
Abstract Key message We provide data on seedlot germination potential—a key trait related to regeneration—of 12 oak species. Germination was tested at the University of Granada following international protocols with 8985 acorns from 93 batches and 16 countries across Europe. Data on germination probability, acorn origin, mass, and moisture content measured on another 4544 acorns are available at https://doi.org/10.30827/Digibug.87318. Associated metadata are available at https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/a742c6d8-bc37-4ca2-8b81-2447c5a8858d.
Variability of Functional Groups of Rhizosphere Fungi of Norway Spruce (Picea abies (L.) H.Karst.) in the Boreal Range: The Wigry National Park, Poland
Rhizosphere microbial communities can influence plant growth and development. Natural regeneration processes take place in the tree stands of protected areas, which makes it possible to observe the natural changes taking place in the rhizosphere along with the development of the plants. This study aimed to determine the diversity (taxonomic and functional) of the rhizosphere fungal communities of Norway spruce growing in one of four developmental stages. Our research was based on the ITS region using Illumina system sequencing. Saprotrophs dominated in the studied rhizospheres, but their percentage share decreased with the age of the development group (for 51.91 from 43.13%). However, in the case of mycorrhizal fungi, an opposite trend was observed (16.96–26.75%). The most numerous genera were: saprotrophic Aspergillus (2.54–3.83%), Penicillium (6.47–12.86%), Pyrenochaeta (1.39–11.78%), pathogenic Curvularia (0.53–4.39%), and mycorrhizal Cortinarius (1.80–5.46%), Pseudotomentella (2.94–5.64%) and Tomentella (4.54–15.94%). The species composition of rhizosphere fungal communities was favorable for the regeneration of natural spruce and the development of multi-generational Norway spruce stands. The ratio of the abundance of saprotrophic and mycorrhizal fungi to the abundance of pathogens was high and promising for the durability of the large proportion of spruce in the Wigry National Park and for forest ecosystems in general.
Shields against pollution: phytoremediation and impact of particulate matter on trees at Wigry National Park, Poland
Climate warming, ecological dynamics and nature conservation drive tree diversity in Wigierski National Park, Poland
In response to ongoing climate warming, tree species adapted to colder climates are expected to shift their geographic ranges northward. Within the framework of long-term ecological monitoring in Wigry National Park (northeastern Poland), observed changes in forest biocenoses reflect the combined influence of climate change and natural ecological dynamics. This study compares dendroflora composition and diversity between two monitoring periods, 2011 and 2024, as part of an ongoing effort to track climate-related ecological shifts. Tree observations and measurements were carried out using concentric circular plots. In the largest plots, all trees with a diameter at breast height (d.b.h.) ≥ 12 cm were recorded by species, and their d.b.h. was measured. In the smaller plots, all trees with a d.b.h. ≥ 2 cm and < 2 cm but taller than 30 cm were similarly identified and measured. Data were recorded with Field-Map software integrated with an electronic calliper. The species-level taxonomic data, individual counts and basal area per species and plot were used to calculate biodiversity indices. Over the 13-year interval, a marked increase in overall dendroflora diversity was observed. Notably, the dominance of canopy-forming conifers – Pinus sylvestris and, to a lesser extent, Picea abies – measured as the proportion of individuals or stem density, has declined. This decline of coniferous species has been accompanied by an increase in the abundance and diversity of broadleaved deciduous species, including Tilia cordata, Quercus robur, Betula pendula, and Acer platanoides. Other thermophilous deciduous taxa also exhibited upward trends in both presence and abundance. Furthermore, the exponential of Shannon entropy, reached the highest value when evergreen conifers comprised 35% of the stand composition in 2011 and 18% in 2024. This finding suggests that maximum dendroflora diversity reaches its highest level at an intermediate proportion of conifers presence, rather than under conifers dominance or absence. Collectively, the processes occurring in Wigierski National Park illustrate the gradual shift in ecotonal forest ecosystems from cold-adapted coniferous species to broadleaved deciduous taxa due to ongoing climate change.
Modeling light response of effective quantum efficiency of photosystem II for C3 and C4 crops
Effective quantum efficiency of photosystem II (ΦPSII) represents the proportion of photons of incident light that are actually used for photochemical processes, which is a key determinant of crop photosynthetic efficiency and productivity. A robust model that can accurately reproduce the nonlinear light response of ΦPSII (ΦPSII–I) over the I range from zero to high irradiance levels is lacking. In this study, we tested a ΦPSII–I model based on the fundamental properties of light absorption and transfer of energy to the reaction centers via photosynthetic pigment molecules. Using a modeling-observation intercomparison approach, the performance of our model versus three widely used empirical ΦPSII–I models were compared against observations for two C3 crops (peanut and cotton) and two cultivars of a C4 crop (sweet sorghum). The results highlighted the significance of our model in (1) its accurate and simultaneous reproduction of light response of both ΦPSII and the photosynthetic electron transport rate (ETR) over a wide I range from light limited to photoinhibition I levels and (2) accurately returning key parameters defining the light response curves.
Genomic investigations of successful invasions: the picture emerging from recent studies
ABSTRACTInvasion biology aims to identify traits and mechanisms that contribute to successful invasions, while also providing general insights into the mechanisms underlying population expansion and adaptation to rapid climate and habitat changes. Certain phenotypic attributes have been linked to successful invasions, and the role of genetics has been critical in understanding adaptation of invasive species. Nevertheless, a comprehensive summary evaluating the most common evolutionary mechanisms associated with successful invasions across species and environments is still lacking. Here we present a systematic review of studies since 2015 that have applied genomic tools to investigate mechanisms of successful invasions across different organisms. We examine demographic patterns such as changes in genomic diversity at the population level, the presence of genetic bottlenecks and gene flow in the invasive range. We review mechanisms of adaptation such as selection from standing genetic variation and de novo mutations, hybridisation and introgression, all of which can have an impact on invasion success. This comprehensive review of recent articles on the genomic diversity of invasive species led to the creation of a searchable database to provide researchers with an accessible resource. Analysis of this database allowed quantitative assessment of demographic and adaptive mechanisms acting in invasive species. A predominant role of admixture in increasing levels of genetic diversity enabling molecular adaptation in novel habitats is the most important finding of our study. The “genetic paradox” of invasive species was not validated in genomic data across species and ecosystems. Even though the presence of genetic drift and bottlenecks is commonly reported upon invasion, a large reduction in genomic diversity is rarely observed. Any decrease in genetic diversity is often relatively mild and almost always restored via gene flow between different invasive populations. The fact that loci under selection are frequently detected suggests that adaptation to novel habitats on a molecular level is not hindered. The above findings are confirmed herein for the first time in a semi‐quantitative manner by molecular data. We also point to gaps and potential improvements in the design of studies of mechanisms driving rapid molecular adaptation in invasive populations. These include the scarcity of comprehensive studies that include sampling from multiple native and invasive populations, identification of invasion sources, longitudinal population sampling, and the integration of fitness measures into genomic analyses. We also note that the potential of whole genome studies is often not exploited fully in predicting invasive potential. Comparative genomic studies identifying genome features promoting invasions are underrepresented despite their potential for use as a tool in invasive species control.