Carbon allocation

A fundamental requirement for all living organisms is the ability to acquire and allocate organic carbon. Depending on availability, carbon flux to different parts of an organism or to different molecular forms may need to increase or decrease. An added layer of complexity is introduced in photosynthetic organisms, which have the ability to produce fixed carbon via photosynthesis. Thus, plants must regulate both the rates at which they acquire fixed carbon, as well as the rates at which they use disperse it. Intricate feedback mechanisms mediate photosynthetic rates in response to over-accumulation of photosynthetic products. Conversely, when fixed carbon is limiting, carbon flux within the plants or to particular molecular forms may shift. Control of carbon flux occurs via diverse mechanisms, such as alterations in redox status and via signal transduction pathways that respond to nutrient availability. The characterization of carbon flux regulation is of both basic and applied importance. As the ability to acquire and strategically utilize nutrients is central to all life functions, nutrient response pathways are likely to have been among the first response pathways to evolve. These response pathways are thus intricately intertwined with other signaling and metabolic networks, making them particularly interesting and challenging to study. Control of carbon flux plays a critical role in regulation of plant development and growth, as well as in regulation of both primary and specialized metabolic pathways. In the future, an improved understanding of the control of carbon flux will be a prerequisite for the rational design of strategies to increase plant productivity and biomass production.