Question:
Male sterility of carrot is conditioned by
Male sterility of carrot is conditioned by
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Carrot is highly outcrossed and insect-pollinated.
Using the petaloid type of CGMS is highly preferred over the brown-anther type because it is more stable under varying environmental temperatures.
Using the petaloid type of CGMS is highly preferred over the brown-anther type because it is more stable under varying environmental temperatures.
Updated On: Jul 31, 2026
- Two duplicate nuclear genes
- Single recessive gene
- Single dominant gene
- One complementary recessive gene
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The Correct Option is A
Solution and Explanation
Step 1: Understanding the Concept:
Male sterility is a valuable tool in hybrid vegetable seed production as it eliminates the laborious manual emasculation process.
In carrot (Daucus carota), cytoplasmic-genic male sterility (CGMS) is widely utilized.
Step 2: Detailed Explanation:
There are two primary types of male sterility systems used in carrot hybrid seed production:
1. Brown anther type: The anthers turn brown and shrivel before anthesis.
2. Petaloid type: The stamens are replaced by a whorl of petals, completely preventing pollen development.
The inheritance of the petaloid male sterility in carrot involves an interaction between sterile cytoplasm and nuclear restorer genes.
In many commercial hybrid breeding programs, the expression of this sterility is conditioned by the interaction of specific cytoplasm with two duplicate dominant nuclear genes (often denoted as \( \text{Ms}_4 \) and \( \text{Ms}_5 \)).
Under this duplicate gene action, the presence of either dominant nuclear gene in the sterile cytoplasm maintains the male-sterile phenotype, or vice versa, depending on the specific epistatic interaction of the system.
This duplicate nuclear gene system allows breeders to maintain parent lines efficiently and produce \( 100\% \) hybrid seeds in commercial production plots.
Step 3: Final Answer:
Male sterility in carrot (specifically the petaloid type) is conditioned by two duplicate nuclear genes interacting with sterile cytoplasm.
Male sterility is a valuable tool in hybrid vegetable seed production as it eliminates the laborious manual emasculation process.
In carrot (Daucus carota), cytoplasmic-genic male sterility (CGMS) is widely utilized.
Step 2: Detailed Explanation:
There are two primary types of male sterility systems used in carrot hybrid seed production:
1. Brown anther type: The anthers turn brown and shrivel before anthesis.
2. Petaloid type: The stamens are replaced by a whorl of petals, completely preventing pollen development.
The inheritance of the petaloid male sterility in carrot involves an interaction between sterile cytoplasm and nuclear restorer genes.
In many commercial hybrid breeding programs, the expression of this sterility is conditioned by the interaction of specific cytoplasm with two duplicate dominant nuclear genes (often denoted as \( \text{Ms}_4 \) and \( \text{Ms}_5 \)).
Under this duplicate gene action, the presence of either dominant nuclear gene in the sterile cytoplasm maintains the male-sterile phenotype, or vice versa, depending on the specific epistatic interaction of the system.
This duplicate nuclear gene system allows breeders to maintain parent lines efficiently and produce \( 100\% \) hybrid seeds in commercial production plots.
Step 3: Final Answer:
Male sterility in carrot (specifically the petaloid type) is conditioned by two duplicate nuclear genes interacting with sterile cytoplasm.
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