Translocation in Phloem

Translocation is the transport of sucrose, amino acids, nutrients, etc., from the source to the sink within a plant.

Translocation in the phloem refers to the flow of different chemicals through the tissue of a plant, such as amino acids, sucrose, etc. Due to gravity, the translocation in the phloem is unaffected. Instead, sucrose is transported from the source (leaf) to the site of metabolism or storage, or “sink.” Depending on the plant’s requirements, These source and sink points can be reversed depending on the plant’s need.

Deciduous trees, for instance, exhibit the bidirectional movement of sap in the phloem by moving sugar from the roots to the developing buds in the early spring and from the photosynthesizing leaves to the roots in the summer. The xylem, in contrast, has a unidirectional movement that is always upward. As a result, depending on the situation, the food contained in phloem sap can be transferred in either direction.

Translocation Directions

The direction of movement in the phloem is variable, just like the relationship between the source and sink is. It may be bidirectional, moving either upwards or downwards. This is different from the upward movement seen in the xylem.

1. Downward Translocation: Translocation from the leaves to the stems and roots for consumption and storage is referred to as downward translocation. It occurs in the sieve tubes with the assistance of nearby partner cells.
2. Upward Translocation: It generally happens when seeds, tubers, and other plants are growing. The immature seedling’s higher growth part receives the food once it has been stored and converted into a soluble form, where it remains until the development of green leaves.

Composition of Phloem Sap

Phloem sap is the organic matter that travels via the phloem. It includes water, sucrose, other sugars, amino acids, and hormones (auxin, gibberellins, cytokinins, and abscisic acid). It moves from the places where carbohydrates are made or stored (a sugar source would be leaves that are photosynthesizing, for example) to the places where they are utilized (sugar sinks, like grains). For the components to be carried from the source to sink in the plants, the phloem sap must maintain both an osmotic potential (given by sucrose) and a particular water potential (supplied by water).

In plants, transportation is an important process. From roots to the tips of their leaves, plants carry the water and nutrients which are required to survive. The water and minerals are transported in plants by:

1. Phloem
2. Xylem

Xylem and phloem tissues are present all over the plants. These conducting tissues grow from the roots of trees and ascend through the trunks. Like spider webs, they eventually branch off into the branches and spread even more into every leaf.