Solution: Enclosing ovules in carpel
- 1.) Pollen can only stick to stigma
- 2.) Must grow a long pollen tube to get to egg.
- 3.) Carpel interacts chemically with pollen and pollen tube
- a.) Stigma and pollen- protein interaction.
- -Favorable: Pollen tube allowed to grow.
- -Unfavorable: Not allowed to grow.
- b.) Carpel tissue and pollen tube- protein interaction
- -Favorable: Allows continued growth.
- - Unfavorable: Pollen tube killed by carpel with RNAase.