Summary• Leaves of Arabidopsis thaliana grown under elevated or ambient CO 2 (700 or 370 µmol mol − 1 , respectively) were examined for physiological, biochemical and structural changes.• Stomatal characters, carbohydrate and mineral nutrient concentrations, leaf ultrastructure and plant hormone content were investigated using atomic absorption spectrophotometry, transmission electron microscopy and enzyme-linked immunosorbent assay (ELISA).• Elevated CO 2 reduced the stomatal density and stomatal index of leaves, and also reduced stomatal conductance and transpiration rate. Elevated CO 2 increased chloroplast number, width and profile area, and starch grain size and number, but reduced the number of grana thylakoid membranes. Under elevated CO 2 , the concentrations of carbohydrates and plant hormones, with the exception of abscisic acid, increased whereas mineral nutrient concentrations declined.• These results suggest that the changes in chloroplast ultrastructure may primarily be a consequence of increased starch accumulation. Accelerated A. thaliana growth and development in elevated CO 2 could in part be attributed to increased foliar concentrations of plant hormones. The reductions in mineral nutrient concentrations may be a result of dilution by increased concentrations of carbohydrates and also of decreases in stomatal conductance and transpiration rate.

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The involvement of actin filaments (AFs) in vesicle trafficking, cell wall construction and tip growth was investigated during pollen tube development of Picea meyeri. Pollen germination and tube elongation were inhibited in a dose-dependent manner by the latrunculin B (LatB) treatment. The fine AFs were broken down into disorganized fragments showing a tendency to aggregate. FM4-64 labeling revealed that the dynamic balance of vesicle trafficking was perturbed due to F-actin disruption and the fountain-like cytoplasmic pattern changed into disorganized Brownian movement. The configuration and/or distribution of cell wall components, such as pectins, callose and cellulose, as well as arabinogalactan proteins changed in obvious ways after the LatB application. Fourier transform infrared (FTIR) analysis further established significant changes in the chemical composition of the wall material. Our results indicate that depolymerization of AFs affects the distribution and configuration of cell wall components in Picea meyeri pollen tube by disturbing vesicle trafficking.