Question

In plants, the photoassimilates are translocated as

• A. Sucrose
• B. Sorbitol
• C. Stachyose
• D. Sucrose, Sorbitol and Stachyose

Hint:

Reducing sugars (like glucose and fructose) are not translocated in the phloem because their free reactive aldehyde or ketone groups can react with other proteins and compounds, disrupting transport.
Plants selectively translocate non-reducing sugars instead.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
During photosynthesis, plants produce carbohydrates (photoassimilates) in their leaves (source).
These sugars must be translocated through the phloem to other parts of the plant like roots, fruits, and growing tips (sinks) for storage and energy.

Step 3: Detailed Explanation:
Let us analyze the chemical forms of sugars translocated in plants:
Plants translocate photoassimilates primarily as non-reducing sugars because they are chemically stable and less reactive than reducing sugars like glucose or fructose.
1. Sucrose:
This is the most common non-reducing disaccharide used for translocation in the vast majority of plant species.
2. Sorbitol (and Mannitol):
These are sugar alcohols.
Some plant families, particularly the Rosaceae (which includes apples, pears, and peaches), translocate a significant portion of their photoassimilates as sorbitol.
3. Stachyose (and Raffinose):
These are non-reducing oligosaccharides.
Families like Cucurbitaceae (melons, squashes) and Lamiaceae translocate sugars primarily as stachyose and raffinose alongside sucrose.
Therefore, depending on the plant family, photoassimilates can be translocated as sucrose, sorbitol, or stachyose.

Step 4: Final Answer:
In plants, photoassimilates can be translocated as sucrose, sorbitol, and stachyose.
Therefore, the correct option is (D).