Ovule culture is a plant tissue culture technique involving the in vitro cultivation of immature ovules, typically employed when seed development is hindered post-pollination due to incompatibility issues.
In more detail:
Ovule culture serves as a rescue mechanism in plant breeding. When successful pollination occurs, but the resulting seeds fail to develop properly because of incompatibility barriers, scientists can intervene. This technique involves aseptically removing the immature ovules from the plant and placing them on a nutrient-rich medium in a controlled environment to encourage their development into viable embryos or plantlets. This approach is particularly useful when fertilization has occurred, but seed maturation is arrested at an early stage.
Why is it used?
- Overcoming Incompatibility: It bypasses incompatibility barriers that prevent normal seed development.
- Embryo Rescue: It rescues embryos that would otherwise abort in vivo.
- Hybrid Production: It facilitates the production of interspecific and intergeneric hybrids.
- Reduced Breeding Time: It shortens the breeding cycle in some plant species.
How Does It Work?
- Selection of Ovules: Immature ovules are selected a few days after fertilization (timing is critical for success).
- Sterilization: Ovules are surface-sterilized to prevent contamination.
- Nutrient Medium: The ovules are placed on a specialized nutrient medium containing sugars, minerals, vitamins, and plant growth regulators (e.g., auxins, cytokinins).
- Controlled Environment: The cultures are maintained under controlled temperature, light, and humidity.
- Embryo Development: The ovules are monitored for embryo development.
- Plantlet Regeneration: Once embryos are developed, they can be further cultured to develop into plantlets.
Example:
Ovule culture has been successfully used in producing interspecific hybrids in crops like rice and lettuce, where normal sexual reproduction is difficult or impossible due to pre- or post-zygotic incompatibilities.
