What is Heteromorphic Self-incompatibility – Definition?
Heteromorphic self incompatibility is associated with flower morphology, exists in heterostylous flowers. Do not have much importance in crop plants.
The genes responsible for self-incompatibility in heterostylous flowers are strongly linked to the genes responsible for flower polymorphism, so these traits are inherited together.
The associated concepts are distyly and tristyly.
What is Distyly? – Definition
Here, both stamens and styles are of two types.
Stamens may be low and high; styles short and long. It is determined by a single gene, with two alleles.
The flower with short style and high stamen is called as thrum type and flower with long style and low stamen is called as pin type. Both thrum and pin flowers differ for six characters in addition to stamen and style length.
| Cross | Result |
|---|---|
| Ss (thrum) X Ss (thrum) | Incompatible |
| ss (pin) X ss (pin) | Incompatible |
| Ss(thrum) X ss (pin) | 1:1 |
| ss (pin) X Ss(thrum) | 1:1 |
What is Tristyly? – Definition
In tristyly, styles and stamens have three different positions.
It is determined by two genes S and M, each with two alleles. S gives rise to short style, S and M to medium style and s and m to long style. The number of possible genotypes is greater, but a 1:1 ratio exists between individuals of each SI type.
Visit homomorphic self incompatibility, this page provides information on the topic and links to the sporophytic and gametophytic self incompatibility.