how are photosynthates transported to underground storage organs from the site of their synthesis??
Photosynthates or the product of photosynthesis is transported from the leaves to other parts of the plants via phloem by the process of translocation from the source (leaves) to the sink (​cells which require food material for growth and repair).
The process can be explained as follows:
Glucose prepared at the source is converted into sucrose. Sucrose is moved to the companion cells, and then to the living phloem sieve tube cells by active transport. This process of loading creates a hypertonic condition in the phloem. Water in the adjacent xylem moves into the phloem by osmosis. As osmotic pressure builds up the phloem sap will move to the areas of lower pressure. At the sink (having reduced osmotic pressure), incoming sugars are actively transported out of the phloem as complex carbohydrates.
The process can be explained as follows:
Glucose prepared at the source is converted into sucrose. Sucrose is moved to the companion cells, and then to the living phloem sieve tube cells by active transport. This process of loading creates a hypertonic condition in the phloem. Water in the adjacent xylem moves into the phloem by osmosis. As osmotic pressure builds up the phloem sap will move to the areas of lower pressure. At the sink (having reduced osmotic pressure), incoming sugars are actively transported out of the phloem as complex carbohydrates.