Tag: Photosynthesis

Cell walls are complex mixtures of cellulose microfibrils, proteins and other materials. Their mechanical properties can be measured and modeled, but it is not always simple to translate these measurements to changes at the molecular level. Zhang et al. used atomic force microscopy to provide an unprecedented…

Plant growth is often limited by the availability of nitrogen (N), which is required to synthesise monomers and macromolecules, and is especially important in the synthesis of the carbon assimilating enzymes of the Calvin-Benson-Bassham (CBB) cycle.  In this article, Kelly has demonstrated that photosynthetic…

A major factor in determining photosynthetic rate is the availability of CO2 at the site of fixation in the chloroplast stroma.  Classically, this has been thought to be mainly limited by stomatal conductance (diffusion from the air, through stomata, to sub-stomatal cavities).  However, more recently…

Mesophyll CO2 conductance (gm) is an important factor in determining the concentration of CO2 at the site of fixation in the chloroplast stroma, and as such is crucial for determining photosynthetic capacity.  The mesophyll cell wall provides a major site of resistance to CO2 diffusion into the stroma…

It is relatively simple to determine net O2 flux in leaves.  However, this data provides no information on the underlying processes responsible for this flux, namely gross oxygen production (GOP, water splitting), mitochondrial respiration in light, Rubisco oxygenation, and photorespiration.  In this…

Phosphorus (P) is an essential macronutrient, and P deficiency limits plant productivity. P influences many aspects of photosynthesis P-deficient plants typically remain green and do not develop leaf chlorosis and yet P starvation immediately affects CO2 assimilation. Specifically, P deficiency is believed…

The carbon-fixing enzyme Rubisco (Ribulose‐1,5‐bisphosphate carboxylase/oxygenase) is much-maligned and has been described as “sluggish” and with “confused specificity”. In this new Review, Bathellier et al. argue that it is “not really so bad”. Their reasoning is that when Rubisco’s…

Following up on earlier studies in which they introduced cyanobacterial Rubisco into tobacco, Lin and Hanson endeavoured to introduce into tobacco Rubisco genes from a red alga, which has an unusually high CO2/O2 specificity. Although they were able to demonstrate the presence of the genes and their…

Phosphorus deficiency is widespread and can severely limit plant growth.  Carstensen et al. investigated how P deficiency affects photosynthesis in barley. They compared chlorophyll a fluorescence transients (OJIP transients) between P-deficient, sufficient and resupplied plants. They observed depletion…