Biology subjects

Zoerb, C.

Publications and source records attributed to Zoerb, C..

3 recordsLinked to original sources

bioRxiv2026

Stomatal Complex Ionomes Explain Divergent Gas Exchange Responses to Salinity in Maize and Faba Bean

Salinity tolerance is commonly associated with whole leaf Na exclusion and maintenance of K homeostasis, but whether spatial ion partitioning among functional leaf compartments contributes to stress adaptation remains unclear. Here, we investigated the relationship between bulk leaf and stomatal complex ionomes and gas exchange performance under salinity using two contrasting genotypes in both maize and faba bean crops. Maize generally maintained higher photosynthesis and stomatal conductance than faba bean under salt stress, which was associated with lower Na accumulation, stronger K retention and distinct ion partitioning patterns between bulk leaf tissue and the stomatal complex. Enrichment analysis revealed that stomatal complex ion composition provided information beyond bulk leaf ion concentrations, with Na and Cl- showing distinct distribution patterns associated with photosynthetic performance. Integrating physiological and ionomic traits further demonstrated that stomatal-complex ion traits captured additional variation in salinity responses. These findings identify the stomatal complex as a functionally distinct ionomic compartment and reveal compartment-specific ion partitioning as an important mechanism underlying species-specific salinity tolerance.

plant biology↗

bioRxiv2026

Guard Cell Chloroplast Remodeling Under Salt Stress Correlates with Ion Enrichment in Faba Bean

Salinity stress alters cellular ion homeostasis and photosynthetic activity, yet how guard cell chloroplast architecture contributes to salt adaptation remains poorly understood. Here, we investigated salt-induced chloroplast remodeling in guard cells of two faba bean genotypes, Fuego and Scoop, by integrating 3D chloroplast imaging, ion enrichment analysis and photosynthetic measurements. Salt stress induced distinct genotype-dependent changes in chloroplast morphology, with Fuego exhibiting pronounced chloroplast enlargement and reduced surface area-to-volume ratios under Na2SO and high NaCl, whereas Scoop showed treatment-dependent remodeling with larger chloroplasts under low NaCl and higher surface area-to-volume ratios under Na2SO and CaCl2. These structural responses were associated with differential Na and Cl partitioning at the stomatal complex surface. In Fuego, chloroplast size was negatively associated with photosynthetic rate, whereas Scoop showed positive relationships between chloroplast size and photosynthetic performance. Multivariate analysis further revealed coordinated associations among chloroplast architecture, ion enrichment and photosynthesis that distinguished the two genotypes under salinity. Our findings demonstrate that guard cell chloroplast remodeling is closely associated with genotype-specific salt responses and local ion partitioning. Integrating organelle structural plasticity with local ion homeostasis provides a spatially resolved perspective on the cellular basis of genotype-dependent salinity adaptation.

plant biology↗

bioRxiv2024

Application of cryo-FIB-SEM for investigating organelle ultrastructure in guard cells of higher plants

Stomata are vital for CO2 and water vapor exchange, with guard cells aperture and ultrastructure highly responsive to environmental cues. However, traditional methods for studying guard cell ultrastructure, which rely on chemical fixation and embedding, often distort cell morphology and compromise membrane integrity, leaving no suitable methodology until now. In contrast, plunge-freezing in liquid ethane rapidly preserves cells in a near-native vitreous state for cryogenic electron microscopy. Using this approach, we applied Cryo-Focused Ion Beam-Scanning Electron Microscopy (cryo- FIB-SEM) to study the guard cell ultrastructure of Vicia faba, a higher plant model chosen for its sensitivity to external factors and ease of epidermis isolation, advancing beyond previous cryo-FIB-SEM applications in lower plant algae. The results firstly introduced cryo-FIB-SEM volume imaging, enabling subcellular ultrastructure visualization of higher plants like V. faba in a vitrified, unaltered state. 3D models of organelles such as stromules, chloroplast protrusions, chloroplasts, starch granules, mitochondria, and vacuoles were reconstructed from cryo-FIB-SEM volumetric data, with their surface area and volume initially determined using manual segmentation. Future studies using this near-native volume imaging technique hold promise for investigating how environmental factors like drought or salinity influence stomatal behavior and the morphology of guard cells and their organelles.

plant biology↗