CLASSIFICATION OF SELF INCOMPATIBILITY
Self-incompatibility can be classified on the basis of
- flower morphology
- genes involved
- site of expression of self-incompatibility reaction and
- pollen cytology
| Basis of classification | Types of incompatibility | Brief description |
| Flower morphology | a. Heteromorhphic | Self incompatibility is associated with differences in flower morphology |
| i. Distyly | Styles and stamens are of two types i.e. short and long. | |
| ii. Tristyly | Styles and stamens have three positions i.e. short medium and long. | |
| b. Homomorhphic | Flowers do not differ in morphology | |
| i. Saprophytic | Self-incompatibility is governed by genotype of pollen producing plant. | |
| ii. Gametophytic | Self-incompatibility is governed by genetic constitution of gametes. | |
| Genes involved | a. Monoalble | Self-incompatibility is governed by single gene |
| b. Diallelic | Self-incompatibility is governed by two genes | |
| c. Polyallelic | Self-incompatibility by several genes | |
| Site of expression | a. Stigmatic | Self-incompatibility genes express on the stigma |
| b. Stylar | Self-incompatibility express in the style | |
| c. Ovarian | Self-incompatibility express in the ovary | |
| Pollen cytology | a. Binucleate | Pollen grains have two nuclei |
| b. Trinuleate | Pollen grains have three nuclei. |
SELF INCOMPATIBILITY
Based on flower morphology, self-incompatibility system is of two types.
- Heteromorphic system.
- Homomorphic system
- Gametophytic control
- Sporophytic control
