Question

Define the male sterility and self-incompatibility.

Hint:

Remember: Male sterility is the failure to produce functional pollen (used in hybrid seed production). Self-incompatibility is a genetic mechanism that prevents self-fertilization by rejecting self-pollen (promotes cross-pollination).

Answer 1

Step 1: Definition of Male Sterility.
Male Sterility is a condition in plants where the male reproductive organs (anthers) are either absent, non-functional, or fail to produce viable pollen grains. The female reproductive organs remain normal and functional. Male sterility is an important tool in hybrid seed production as it eliminates the need for manual emasculation. Types of male sterility:

• Genetic Male Sterility (GMS): Controlled by nuclear genes
• Cytoplasmic Male Sterility (CMS): Controlled by mitochondrial genes
• Cytoplasmic-Genetic Male Sterility (CGMS): Interaction of nuclear and cytoplasmic genes

Uses:

• Facilitates hybrid seed production
• Eliminates emasculation cost and labor
• Ensures high purity of hybrid seeds

Examples: Onion, carrot, maize, sunflower, rice \vspace{0.3cm}
Step 2: Definition of Self-Incompatibility.
Self-Incompatibility is a genetic mechanism in flowering plants that prevents fertilization by pollen from the same flower or same plant. The pistil recognizes and rejects self-pollen, thereby promoting cross-pollination and outbreeding. Types of self-incompatibility:

• Gametophytic Self-Incompatibility (GSI): Rejection determined by pollen's own genotype (e.g., Apple, Pear, Tomato)
• Sporophytic Self-Incompatibility (SSI): Rejection determined by pollen parent's genotype (e.g., Cabbage, Mustard, Sunflower)

Mechanism:

• Recognition proteins on pollen and stigma
• If same S-alleles present, pollen germination or tube growth is inhibited
• Prevents inbreeding depression

Uses:

• Promotes genetic diversity
• Useful in hybrid breeding programs
• Maintains heterozygosity

Examples: Brassica (cabbage, cauliflower), radish, apple, pear