Carbon sources in plant tissue culture — which carbohydrate is most commonly used in media formulations?

Introduction / Context:
Plant cells in vitro are typically heterotrophic and require an exogenous carbon source. Media such as MS, B5, and WPM almost always include a carbohydrate; choosing the right one affects osmotic potential, callus growth, and morphogenesis.

Given Data / Assumptions:

• Question asks for the most common carbon source in standard culture media.
• Typical concentrations are around 20–30 g/L.
• Alternatives like glucose and fructose are sometimes used but less common.

Concept / Approach:

Sucrose is the dominant carbohydrate in plant tissue culture. It is inexpensive, readily available, and, upon autoclaving or in culture, can hydrolyze to glucose and fructose, which cells readily take up. Its osmotic properties and compatibility with a wide range of explants make it the default choice.

Step-by-Step Solution:

Verification / Alternative check:

Protocol collections and manufacturer datasheets list sucrose as the standard carbon source across most species and explant types.

Why Other Options Are Wrong:

Glucose and fructose are used occasionally but are not the general default. Maltose is more niche. Lactose is rarely used in plant culture.

Common Pitfalls:

Assuming glucose is preferred because it is a primary metabolite; in practice, sucrose’s handling and osmotic traits make it superior.

Final Answer:

Sucrose