Abstract Cadmium (Cd) contamination poses a major threat to forest ecosystems, and Broussonetia papyrifera is a promising woody species with strong Cd tolerance and accumulation capacity. Vacuolar H + ‐ATPase (V‐ATPase) is central to ion homeostasis and heavy metal detoxification, yet the organ‐ and domain‐specific roles of its subunits in Cd responses remain unclear. We integrated physiological measurements, transcript profiling, enzyme activity assays and genome‐wide analyses to characterize V‐ATPase subunits ( BpVHAs ) and their functions under a 30‐day Cd treatment in roots, stems and leaves of B. papyrifera . Cd stress caused only mild electrolyte leakage but triggered substantial V‐ATPase accumulation and enhanced activity. V‐ATPase activity displayed a tissue‐graded temporal pattern, with roots responding earliest and most strongly. We identified 22 BpVHA genes belonging to conserved V 0 and V 1 domains, whose promoters were enriched in stress‐ and hormone‐related cis ‐elements. Most genes exhibited a rise‐then‐fall expression trend during Cd exposure, with V 0 subunits induced earlier, more strongly and for longer than V 1 subunits. Mantel tests showed that V 1 expression correlated more strongly with V‐ATPase activity in roots, whereas V 0 expression dominated in stems and leaves. Our findings highlight BpVHA‐a2 , BpVHA‐a3 and BpVHA‐c1 as key contributors to Cd detoxification. We propose a model in which roots rely on rapid V 1 ‐driven ATP hydrolysis, while aerial tissues depend on sustained V 0 ‐mediated proton pumping to support vacuolar Cd sequestration. This study provides new insights into heavy metal tolerance in woody plants and identifies promising molecular targets for breeding and phytoremediation in Cd‐contaminated environments.
Abstract Mechanical interactions are increasingly recognized as integral components of plant development, yet their contribution to cell‐fate decisions remains incompletely understood. Here, we examine how spatial organization, growth heterogeneity and mechanical constraints contribute to developmental patterning in plant tissues. Using Arabidopsis, tobacco and tomato as experimental systems, we combined three‐dimensional confocal imaging, quantitative analysis of cell and nuclear geometry, and perturbation of growth and developmental state. Root hair morphogenesis and vascular differentiation were examined in relation to spatial position, cellular geometry and local developmental context. Our analyses reveal structured relationships between cell geometry, position and developmental state. During root hair development, changes in cellular organization are associated with spatially patterned growth behaviour. In vascular tissues, xylem and phloem differentiation likewise occur within geometrically constrained cellular environments. Together, these observations indicate that heterogeneous growth generates distinct local mechanical contexts associated with developmental transitions. We propose that mechanical interactions should be considered an active component of plant signalling rather than simply a consequence of growth. Integrating biochemical regulation with tissue geometry and mechanically generated context provides a more complete framework for understanding how plant cells coordinate fate, growth and differentiation across scales.
Abstract Plant reproduction along elevational gradients may be limited by insufficient pollination service, variation in selfing capacity or post‐pollination constraints, yet these mechanisms are rarely studied together across multiple co‐occurring species. We examined how seed production, pollen limitation and selfing capacity vary along the full elevational gradient of Afromontane grasslands on Mount Cameroon. We combined a hand‐pollination experiment with recordings of flower visitors at four elevations above the timberline (2300–3800 m a.s.l.). In seven zoogamous species, we quantified natural seed production, pollen limitation and indices of autonomous and facilitated selfing from controlled pollination treatments, while independently measuring visitation frequency and visitor diversity on unmanipulated plants. Natural seed production peaked at intermediate elevation and declined sharply towards the summit, where the pollen‐limitation index was highest. At the highest elevation, some species produced few or no seeds even after supplemental outcrossing. Autonomous and geitonogamous selfing capacities showed no consistent elevational trends despite partial self‐compatibility in several species. Visitation frequency and diversity declined towards the summit, and natural seed production increased with visitation frequency, whereas pollen limitation and selfing indices showed no clear relationships with visitation metrics. Together, our results indicate that elevational variation in reproductive success is linked to changes in pollination service, but that pollen limitation and selfing capacity do not track visitation in a simple way. No increase in selfing capacity towards the summit suggests limited potential for increased reproductive assurance through selfing under high‐elevation conditions, while additional processes after pollen delivery may also constrain seed production near upper vegetation limits.
Abstract The invasive South African plant Carpobrotus edulis threatens biodiversity and disrupts coastal ecosystems, yet the effects of soil legacies on the life cycle of native plants remain poorly understood. Here, we assessed whether a short‐term invasion by C. edulis induces soil changes that remain after removal and affect the performance of the endangered dune plant Iberodes littoralis subsp. gallaecica across its life cycle. In 16 experimental plots (eight previously invaded and eight non‐invaded), we characterised soil properties at two depths and sowed seeds from five I. littoralis populations to assess germination, survival to flowering, flowering phenology, flower number, leaf reflectance, biomass traits and reproductive output. Previously invaded plots showed reductions in NH 4 + –N, total N, Cu and Zn, and increases in δ 13 C, P and Al, while invasion effects on NO 3 − –N and pH varied with soil depth, as did soil–plant relationships. Soil legacies promoted germination in I. littoralis but reduced survival to flowering, flowering duration, growth and reproductive investment, ultimately resulting in lower seed production. Despite phenotypic differences among provenances, intra‐specific variation did not mitigate the adverse effects of soil legacies on plant performance. Our findings show that just 14 months of C. edulis invasion can leave soil legacies in nutrient availability and soil chemistry, with functional consequences for I. littoralis across its full life cycle. These results highlight the importance of considering legacy effects of invasion beyond early life stages of native plants and accounting for depth‐related variation in soil properties and soil–plant relationships in restoration planning.
Orchid seeds primarily contain lipid reserves, yet details of their deposition, in quantity and quality, remain unknown. Deposition begins as carbohydrates, which are eventually converted into fatty acids during seed development. This research aimed to dissect the pattern of lipid deposition in seeds of Dactylorhiza fuchsii and Disa uniflora, from pollination to seed storage, including at five stages of seed maturation, germination capacity and relationships among fatty acids (FAs). The capsules were harvested, cleaned and measured. Extracted seeds were analysed using differential scanning calorimetry (DSC), moisture content determinations, in vitro germination tests in three different media and seed viability. A portion of the seeds was dried to analyse lipid content and types via Gas Chromatography-Mass Spectrometry (GC-MS). While Dact. fuchsii seeds showed a high percentage of dry matter at the end of maturation, Disa uniflora had a lower one. Lipid accumulation profiles differed. The proportions of saturated and unsaturated FA varied, with Disa uniflora having more saturated FA than Dact. fuchsii. Seeds began to germinate before the midpoint of capsule maturation, and germination increased with maturation time in both species, with Disa uniflora seeds reaching full germination at capsule dehiscence. Conversely, Dact. fuchsii seeds did not germinate because the seed carapace may hinder germination. Nevertheless, at capsule maturity, seeds from both species were highly viable based on the tetrazolium test. Mature seeds of both species were desiccation-tolerant (4.5% RH) and could be stored dry at 5 degrees C for 3 months without loss of viability, suggesting the possibility of long-term seed banking for conservation.
