Variation in growth rate and ecophysiology among 34 grassland and savanna species under contrasting N supply: a test of functional group differences.

•   We tested the hypothesis that biological trait-based plant functional groups provide sufficient differentiation of species to enable generalization about a variety of plant ecophysiological traits or responses to nitrogen (N). •   Seedlings of 34 North American grassland and savanna species, representing 5 functional groups, were grown in a glasshouse in an infertile soil with or without N fertilization. •   Forbs, C and C grasses, on average, had similar relative growth rates (RGR), followed in declining order by legumes and oaks, but RGR varied greatly among species within functional groups.

Plant diversity enhances ecosystem responses to elevated CO2 and nitrogen deposition.

Human actions are causing declines in plant biodiversity, increases in atmospheric CO2 concentrations and increases in nitrogen deposition; however, the interactive effects of these factors on ecosystem processes are unknown. Reduced biodiversity has raised numerous concerns, including the possibility that ecosystem functioning may be affected negatively, which might be particularly important in the face of other global changes. Here we present results of a grassland field experiment in Minnesota, USA, that tests the hypothesis that plant diversity and composition influence the enhancement of biomass and carbon acquisition in ecosystems subjected to elevated atmospheric CO2 concentrations and nitrogen deposition.

Phospholipid composition of chlorophyll-free mitochondria isolated via protoplasts from oat mesophyll cells.

Mitochondria were isolated from oat primary leaves via mesophyll protoplasts and subjected to phospholipid analysis. In mesophyll cells mitochondria account for only small proportions of cellular phospholipids (in the order of 5%) and proteins (in the order of 2%). Contamination by lipids from other membranes was insignificant as indicated by the absence or very low levels of chlorophyll, galactolipids and steryl glycosides.

Localization of sulfolipid labeling within cells and chloroplasts.

Spinach chloroplasts were purified on gradients of Percoll which preserved envelope impermeability and CO2-dependent oxygen evolution in the light. Application of (35)SO4″ to purified chloroplasts resulted in a light-dependent labeling of a lipid component which was indentified as sulfoquinovosyl diacylglycerol. Fractionation of chloroplasts showed that after 5 min of labeling most of the newly synthesized sulfolipid was present in thylakoids.