Belgium

Stomata arise during leaf epidermal development as specialised structures for gas-exchange. Stomatal numbers, apertures and distribution between leaf surfaces can affect plant water balance, growth and yield. While the mechanisms that govern the formation of stomata on the abaxial (lower) leaf surface are well-studied, how stomata develop on the adaxial (upper) leaf surface is poorly understood. How the distribution of stomata between leaf sides (stomatal ratio) is determined and adjusted in response to plant growth environment also remains unclear.
We addressed the effects of environmental conditions on adaxial and abaxial stomatal patterns in Arabidopsis thaliana. Acclimation to dry air or warm temperatures in Arabidopsis leaves manifests in substantial changes in stomatal density, small changes in stomatal ratio and minor, if any, changes in stomatal index. Thus, acclimation to growth environment may be mostly mediated by changes in cell expansion and less by alterations in leaf developmental program.
We also explored the relationships between stomatal anatomical traits and yield in crops. In spring wheat that has relatively more stomata on the adaxial leaf surface, higher adaxial but not abaxial stomatal density was negatively associated with yield, especially under dry and warm conditions. In tomato that has less stomata on the adaxial than abaxial leaf surface, higher stomatal ratios were positively associated with yield. Thus, manipulation of adaxial stomatal densities and stomatal ratios may increase yield in both monocot and dicot crops. Understanding how adaxial stomatal development is controlled and how stomatal ratios are regulated is necessary to achieve this goal.

SEB Conference 2025

Stomatal distribution between leaf surfaces and its relationships with yield

stomatal ratio

stomatal patterning

stomatal development

stomatal density

yield

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technical paper

Proboscideans (e.g. elephants, mammoths, and mastodons) include some of the largest known land mammals. Their limbs evolved a columnar structure and unique reorientation to withstand extreme vertical compression. Recent studies identified two distinct limb morphotypes—robust and gracile—independent of body mass, raising questions about their functional differences under compressive loads. To explore the functional implications of these morphotypes, we used finite element analysis (FEA) to simulate compressive forces on proboscidean humeri. Our results show that the broader, more robust morphotype resists compressive stress more effectively than the slimmer morphotype, suggesting functional specialisations in load-bearing strategies. While FEA is rarely applied to bone compression tests, our findings highlight its potential for investigating biomechanical adaptations in graviportal species. This study enhances our understanding of proboscidean limb evolution and establishes a methodological framework applicable to other large-bodied taxa, such as sauropod dinosaurs.

Testing Functional Differences in Proboscidean Limb Morphotypes Under Compression Using Finite Element Analysis

Sabre-toothed cats (Felidae: Machairodontinae†) are considered to have wide gape angles compared to conical toothed cats (e.g. lions, leopards, etc.). Intuitively, a wider gape may have allowed for larger prey to be dispatched with a neck bite. In this study, we took an experimental approach using 3D-printed skulls to investigate maximum gape angles in African cats from the Pliocene-to-Holocene (including conical and sabre-tooth cats). We tested whether representative skulls could physically fit around the neck, upper throat, and muzzle of high-quality taxidermed models of potential prey items (including suids, gazelle, antelope and bovids, rhinocerotids, and proboscideans). To account for soft tissue restrictions on maximum gape, we conducted a comparative study on fully-fleshed and de-fleshed heads of house cats (Felis catus), leopard (Panthera pardus), and lion (P. leo), examining both maximum myological (fully fleshed) and osteological gape angles. Osteological gape angles were larger across the specimens; we therefore used the highest, lowest, and mean differences in angles between osteological and myological gape angles as a range of conservative correction-factors for the gape angles of the 3D-printed skulls. Current results indicate comparable killing potential between medium-sized sabre-tooth cats (Dinofelis, Megantereon, Lokotunjailurus) and modern leopards and cheetahs. The extremely long sabres of Megantereon prevented the initiation of a killing bite on many medium and large ungulates, including adult alcelaphine, tragelaphine, and reduncine bovids (e.g. Kobus ellipsiprymnus). Finalising experimental results and applying prey-preference analyses will provide a more tangible range of prey which African sabre-tooths could have physically killed.

Wide is the gape that feeds - examining the physical constraints of biting in conical and sabre-toothed felids

Accurately distinguishing and classifying fibre types within composite bundles presents significant challenges, particularly for micro-scale fibres arranged in hierarchical structures. Biological fibre composites, such as spider silk or arterial walls, contain fibres that cannot be easily isolated, while their minimal mass makes characterisation through conventional techniques like mass spectroscopy, Raman spectroscopy, or proteomics time-consuming and, in some cases, impossible. In this work, we address this challenge by introducing a new method based on statistical classification and physically-constrained optimization. The approach exploits the ability of obtaining data both from the single fibres, e.g. through scanning electron microscopy, and from the composite fibre network, e.g. mechanical properties. The fibre-dependent data are used to run a labelling procedure using Gaussian Mixture Models. We use this first composition of the fibre sub-populations, as the start of a Mixed-Integer Linear Programming (MILP), to further categorize fibres based on their linear phase behavior, their mechanical properties, and their biological constraints. This integrated methodology proves particularly valuable for natural materials, where multiple fibre types with distinct mechanical functions coexist within a single structure. Through testing, we demonstrate robust classification performance when combining geometrical and mechanical properties. This method successfully distinguishes between overlapping distributions and resolves ambiguities that pure statistical approaches cannot address. To facilitate adoption across disciplines, we provide our implementation as an open-source Python package. By applying this method to other biological fibre networks, we could improve our understanding of how fibre bundles are organised in nature, and how they reach their optimal mechanical performance.

A Hierarchical Cluster-Separation Framework for Analysing Fibre-Based Biological Materials

Insect ovipositors and stingers have extensive variation in their morphology depending on the substrate they penetrate or probe. From an engineering perspective, stingers are micro penetration devices capable of penetrating a substrate and delivering a package. Understanding the role played by the microstructures and substrate property on the insertion and extraction forces will enable us to design efficient bioinspired micro needles and transdermal medical patches.
Quasi-static insertion and extraction experiments on honeybee stingers were conducted on artificial homogeneous substrate(humimic) and fibrous chicken muscle. The force required to remove the stinger from the fibrous substrate was 3 times more than that of in the homogenous substrate due to the rearward facing barb making it harder to pull out. The barbs, in addition to helping the stinger anchor, were found to significantly reduce the insertion forces. The increased stress concentration at the site of the barbs can contribute to the decreased insertion force.  Stingers with barbs were found to require one-third the insertion force in humimic and half the insertion force in the fibrous substrate, compared to modified barbless stingers. In biomedical applications, a reduced insertion force would translate to less pain and less tissue damage. Higher extraction forces could be beneficial in designing mechanically adhering patches.

Assessing the role of  barbs and substrate properties on insertion and extraction forces in worker honeybee stingers

This project explores how life science students' career trajectories and professional identities are shaped by their historical perspectives, curriculum experiences, and interactions with facilitators. Conducted at Imperial College London, it highlights the importance of recognising students' prior experiences and providing support to enhance their engagement with the life sciences discipline.

Traversing the Bridge: How Interactions and Facilitators Influence Career Trajectories and Professional Identities 

The deterioration of indoor air quality (IAQ) poses a serious health risk because of the high concentration levels of CO2  and air pollutants. Within the frame of our project ‘NEUROPLANT’ (NEURal netwOrks trained with measurements of pollutants removal by PLANTs and their associated microbiome at different spatial and temporal scales), this study explores the air phytoremediation potential of plants as an eco-sustainable solution to improve IAQ. We assessed the capacity of three common indoor plant species (i.e. Schefflera actinophylla, Spathiphyllum wallisii and Epipremnum aureum) to reduce ambient CO2  concentration through photosynthesis.  The dynamic response of CO2  assimilation to short-term increasing levels of light and CO2  was measured in leaves of potted plants, that were previously acclimated to chamber high and low light levels. In the short-term photosynthetic efficiency increased in response to elevated CO2  concentrations and high light intensity, whereas long-term exposure to high light likely induced photoinhibition. This suggests that the ability of indoor plant species to improve ambient CO2  assimilation, and in turn IAQ, can be dramatically enhanced by high ambient CO2   concentration, but only to a limited extent by high light levels. Data allowed us to identify key parameters of photosynthetic performance for developing and training an air phytoremediation model, based Long-Short-Term-Memory Recurrent Neural Network (LSTM RNN) artificial intelligence (AI), able to predict the impact of different plant species on IAQ in real indoor settings. This will assist architects and policymakers in designing and optimizing plant-based air purification systems for sustainable improvement of IAQ.

An eco-physiological investigation of indoor plants photosynthetic CO2 sequestration capacity for implementing artificial intelligence (AI) predictive models

Amaranthus sp. (amaranths) is a genus of plants in Amaranthaceae family. Several species, like A. cruentus, are minor crops cultivated for either seed production or for their edible leaves. They are renowned for their tolerance to biotic and abiotic stress and their excellent nutritional quality, making them promising crops in challenging environmental conditions. Soil salinity is one of the main abiotic stress constraining crop growth, mostly in (semi-)arid regions. Most of the crops used today are glycophyte (i.e. salt sensitive); finding salt-tolerant cultivars or new species is therefore a priority for sustainable agriculture. Photosynthetic activity of Amaranthus cruentus (red amaranth, a plant with C4-type photosynthesis) was studied in response to a moderate saline stress (75 mM in irrigation water) in controlled conditions. Analysis of photosynthesis parameters, recorded with an infrared gas analyzer coupled with a fluorimeter (IRGA), showed a deleterious effect of salt stress on the light-independent reactions of photosynthesis (net carbon assimilation), but not on the light-dependent reactions (electron transport rate and quantum yield of photosystem II). Transpiration and stomatal conductance were also affected by salt. Transcriptomic and proteomic analysis were also performed on leaves. Differentially expressed genes and differentially accumulated proteins involved in metabolic pathways related to photosynthesis were used to explain photosynthetic activity data. Finally, chlorophylls and carotenoids content in leaves were compared to IRGA and -omics data.

Effect of salt stress on the photosynthetic activity of four Amaranthus cruentus cultivars

Water use efficiency (WUE) is gaining importance as a key trait to grow crops under water limited conditions. Stomata, the small pores on the leaf surface that govern water and carbon dioxide exchange, exert a key influence on WUE through their conductive capacity (gs). gs maximum and minimum is determined by the size and density of stomata, and operational gs by density and the operational pore.  All these structural features are related based on allometric relationships that take into account the cost of investment in these features for the benefit of higher gas exchange rates. However, the effect these relationships have on WUE especially at different scales has not been fully explored. I present a simple modeling analysis of the effect of stomatal anatomy on WUE, and attempt to scale it using crop models by integrating it with optimality coefficients. Stomatal operational pore (aop) changes in response to environmental conditions. In leaves with high densities, maximum operational pores per surface area is smaller compared to lower density leaves, but high density leaves experience higher rates of increase in gs, and hence photosynthesis, for small changer in aop, making them more sensitive to environmental changes. Attempting to link these anatomical variations to stomatal sensitivity can provide more basis for incorporating stomatal variation in crop models and provide a mechanistic basis for selecting for genetic traits such stomatal density.

Stomatal anatomical basis for crop water use efficiency

Stomata are small microscopic pores that regulate plant gas diffusion and water loss. An increase in food requirements and changes in climate conditions affect global food security. In addition, rising air temperatures and increases in droughts affect changes in stomatal traits and cause stress in plants. Wheat (Triticum aestivum), the most widely cultivated food crop, supplies one-fifth of the total calories of the world’s population. Therefore, it is important to understand how stomata respond to environmental stress factors. So far, it has been found that in wheat the adaxial surface has more stomata compared to the abaxial surface. Still, less is known about the relationship between stomatal traits and grain yield and how stomata behave in different environmental conditions. Field trials were carried out with 25 winter wheat varieties in two years (2023-2024) to investigate stomata anatomical characteristics and their impact on crop formation. Trials in growth chambers with nine winter wheat varieties were conducted under controlled conditions to investigate abaxial and adaxial stomatal sensitivity to changes in relative air humidity. Field trial results showed positive correlations between grain yield and leaf adaxial stomatal density in 2024 and also as two-year averages. In both years, stomatal densities and stomata guard cell length had a negative relationship. In growth chamber trials, adaxial side stomata were more sensitive to changes in air humidity than abaxial side stomata. By understanding how stomatal traits are related to grain yield, we could breed more suitable wheat varieties for changing climate conditions.

Influence of stomatal characteristics on winter wheat grain yield

The mitochondrial membrane lipid composition in ectothermic bivalves plays a crucial role in their ability to adjust fluidity according to the environment. The observed inverse relationship between lifespan and fatty acid unsaturation indicates that increased longevity is associated with the presence of oxidation-resistant membranes. Cardiolipin (CL), a critical mitochondrial lipid, plays a central role in age-related processes such as mitochondrial dynamics and apoptosis, triggered by ROS-mediated CLs oxidation. Moreover, CL's influence on cristae structure and supercomplex organisation, modulated by fatty acid composition, highlights its essential role in maintaining mitochondrial function. To understand its role in longevity, we examined CL fatty acid composition across seven bivalve species, with lifespan ranging from 4 to over 500 years. We predicted that long-lived species would exhibit higher CL content per mitochondrion and distinct polyunsaturated fatty acid profiles within CLs. Our preliminary results confirmed higher CL content in Arctica islandica, the species known for its exceptional longevity. This study explores how CL composition might impact apoptosis and mitochondrial function, potentially revealing climate change resilience mechanisms in long-lived bivalves.

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Testing Functional Differences in Proboscidean Limb Morphotypes Under Compression Using Finite Element Analysis

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Influence of stomatal characteristics on winter wheat grain yield