Question

In vegetatively propagated material somatic mutations of spontaneous origin are commonly referred to as

• A. Cultivar
• B. Variety
• C. Bud sports
• D. Chimera

Hint:

When a spontaneous genetic change (mutation) happens in a bud of a vegetatively propagated plant, it can lead to a branch with different traits. This is called a "bud sport." Many new fruit and ornamental cultivars have originated as bud sports.

Answer 1

The Correct Option is C

Vegetatively propagated plants are clones, meaning they are genetically identical to the parent plant. However, spontaneous mutations can occur in the somatic (body) cells of these plants.
If such a mutation occurs in a cell that gives rise to a bud or a branch, that bud or branch may develop with characteristics different from the rest of the plant (e.g., different flower color, fruit size, leaf variegation, or growth habit).
This mutated bud or branch is known as a bud sport (or simply sport).
Bud sports are a significant source of new cultivars in many vegetatively propagated crops like roses, apples, grapes, and citrus. If the sport has desirable characteristics, it can be propagated vegetatively to create a new cultivar. Let's look at the other options:
(1) Cultivar: A "cultivated variety"; a plant selected for desirable characteristics that are maintained during propagation. A bud sport can become a new cultivar if selected and propagated.
(2) Variety: In botany, "variety" has a specific taxonomic rank. "Cultivar" is preferred for cultivated plants.
(4) Chimera: A plant composed of tissues of two or more genetically different types, often arising from mutation in a meristem. A bud sport can result in a chimera if the mutation affects only some cell layers in the meristem. While related, "bud sport" is the more direct term for the spontaneous somatic mutation leading to a new phenotypic branch or bud. Thus, "bud sports" is the common term for these spontaneous somatic mutations in vegetatively propagated material. Bud sports

Answer 2

Distinguishing by where the term is applied:
"Cultivar" and "variety" are broad classification ranks applied to any distinct, named plant type regardless of how it originated - they don't specifically describe the mutation event itself, so both are ruled out as the specific term being asked for.
"Chimera" describes the internal tissue structure of a plant made of two genetically distinct cell layers, which is a possible internal consequence of a bud mutation, but it is not the general name for the phenomenon of a spontaneous somatic mutation appearing on vegetatively propagated material.
The commonly used horticultural term for a spontaneously arising, genetically different shoot, branch or bud on an otherwise clonal plant is a bud sport - this is the term breeders use when scouting orchards or rose gardens for new mutant branches to propagate.