Photosynthate partitioning is the deferential distribution of photosynthates to plant tissues. A photosynthate is the resulting product of

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...

, these products are generally sugars. These sugars that are created from photosynthesis are broken down to create energy for use by the plant. Sugar and other compounds move via the phloem to tissues that have an energy demand. These areas of demand are called sinks. While areas with an excess of sugars and a low energy demand are called sources. Many times sinks are the actively growing tissues of the plant while the sources are where sugars are produced by photosynthesis—the leaves of plants. Sugars are actively loaded into the phloem and moved by a positive pressure flow created by solute concentrations and

turgor pressure Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall. It is also called ''hydrostatic pressure'', and is defined as the pressure in a fluid measured at a certain point within itself when at equilibriu ...

between

xylem Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived from ...

and

phloem Phloem (, ) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process is ...

vessel elements (specialized plant cells). This movement of sugars is referred to as translocation. When sugars arrive at the sink they are unloaded for storage or broken down/metabolized. The partitioning of these sugars depends on multiple factors such as the vascular connections that exist, the location of the sink to source, the developmental stage, and the strength of that sink. Vascular connections exist between sources and sinks and those that are the most direct have been shown to receive more photosynthates than those that must travel through extensive connections. This also goes for proximity: those closer to the source are easier to translocate sugars to. Developmental stage plays a large role in partitioning, organs that are young such as

meristem The meristem is a type of tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells conti ...

s and new leaves have a higher demand, as well as those that are entering reproductive maturity—creating fruits, flowers, and seeds. Many of these developing organs have a higher sink strength. Those with higher sink strengths receive more photosynthates than lower strength sinks. Sinks compete to receive these compounds and combination of factors playing in determining how much and how fast sinks receives photosynthates to grow and complete

physiological Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

activities.

References

{{reflist Photosynthesis