Erika Ball

Patterns of gas exchange and organic acid oscillations in tropical trees of the genus Clusia

SummaryGas exchange patterns and nocturnal acid accumulation were examined in four species of Clusia under simulated field conditions in the laboratory. Clusia alata and C. major had midday stomatal closure, substantial net CO2 exchange (

Increased Vacuolar ATPase Activity Correlated With CAM Induction in Mesembryanthemum crystallinum and Kalanchoë blossfeldiana cv. Tom Thumb.

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Adenine-nucleotide levels during crassulacean acid metabolism and the energetics of malate accumulation in Kalanchoë tubiflora

) during the night, and the highest water use efficiency (WUE). C. venosa showed a pattern similar to a C3 plant, with nighttime stomatal closure, while C. minor maintained positive

Diurnal patterns of chlorophyll a fluorescence and stomatal conductance in species of two types of coastal tree vegetation in southeastern Brazil

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Flexibility of Crassulacean Acid Metabolism in Kalanchoe pinnata (Lam.) Pers. I. Response to Irradiance and Supply of Nitrogen and Water

continuously throughout a 24-h period. However, large changes in titratable acidity, which closely matched changes in citrate and malate levels, indicated that Crassulacean acid metabolism (CAM) is active in all four species. C. venosa showed dawn-dusk oscillations in titratable acidity that were higher than the values reported for other C3-CAM intermediates, while the nighttime acid accumulation of 998 mol m−3 observed in C. major is unsurpassed by any other CAM plant. Moreover, the dawn-dusk changes in citrate levels of over 65 mol m−3 in C. alata and C. minor, and over 120 mol m−3 in C. major, are 3–6 times higher than values reported for other CAM plants. Although these oscillations in citrate levels were quite large, and the nighttime dark respiration rates were high, the O2 budget analysis suggestes that only part of the reducing power generated by the synthesis of citric acid enters the respiratory chain. Dawn-dusk changes in malate levels were just over 50 mol m−3 for C. venosa but over 300 mol m−3 for C. major. Between 28% (C. major) and 89% (C. venosa) of the malate accumulated during the night was derived from recycled respiratory CO2. These daily changes in malate and citrate levels also contributed significantly to changes in leaf sap osmolality. This variability in CO2 uptake patterns, the recycling of nighttime respiratory CO2, and the high WUE may have contributed to the successful invasion of Clusia into a wide range of habitats in the tropics.

Photosynthesis and apparent proton fluxes in Elodea canadensis

SummaryThe membrane potential of cells in leaf slices of the CAM plantKalanchoë daigremontiana Hamet et Perrier in the light and in the dark is −200 mV on the average; it is reversibly depolarized by the metabolic inhibitors FCCP (5×10−6m) and CN− (5×10−3m); it shows the light-dependent transient oscillations ubiquitously observed in green cells; it is independent of the amount of malic acid accumulated in the cells (in a tested range between 30 and 140mm); and it is considerably hyperpolarized by the fungal toxin fusicoccin (30×10−6m). Fusicoccin inhibits nocturnal malic acid accumulation in intact isolated phyllodia of the CAM plantKalanchoë tubiflora (Harv.) Hamet but does not affect remobilization of malic acid during the day.Electrochemical gradients for the various ions resulting from dissociation of malic acid, i.e., H+, Hmal− and mal2−, were calculated using the Nernst equation. With a very wide range of assumptions on cytoplasmic pH and malate concentration results of calculations suggest uphill transport of H+ and Hmal− from the cytoplasm into the vacuole, while mal2− might be passively distributed at the tonoplast. On the basis of the present data the most likely mechanism of active malic acid accumulation in the vacuoles of CAM plants appears to be an active H+ transport at the tonoplast coupled with passive movement of mal2− possibly mediated by a translocator (“catalyzed diffusion”), with subsequent formation of Hmal− (2 H++mal2−→H++Hmal−) at vacuolar pHs.