Pathways of Translocation

The path that sugars and other molecules take while moving through a plant begins in the organs these nutrients are used. Source regions, or sources, are the organs where the pathway starts, and sink regions, or sinks, The predominant organ for the formation of sugars is the leaf, by the process of photosynthesis, leaf is the primary organ for the production of sugars.

These sugars are transported to other parts of the plant or utilized locally by the leaf. Leaves are the main source regions, mature leaves can act as sources. Young leaves are unable to fully nourish themselves with their own sugar production.

Other sink tissues include growing reproductive tissues like seeds and fruit, which store resources for later use, and root systems, which cannot perform photosynthesis and must be fed by the leaves. Tubers (like potatoes and yams) and tap roots are additional storage organs that function as translocation sinks and are significant crops for human consumption (e.g., carrots and beets). 

The translocation pathway is made up of plant structures like the stem of a herbaceous plant, the trunk, and branches of a tree, or the petiole of a leaf that are situated between terminal source and sink tissues. These tissues act as sinks because each of these structures contains a large number of living cells that need to be fed. However,  they serve dual roles, because in some plants (e.g., cereals such as rice and wheat) the stems act as temporary storage organs for nutrients.

 These stems are transformed into source regions that supply nutrients for the developing seeds at later stages of the plant’s life cycle. Pea pods, for example, can undertake photosynthesis, as can a variety of non-leafy green tissues.

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.