The main difference between gametophytic and sporophytic self-incompatibility is that the incompatibility process is determined by the genotype of male gametophyte in gametophytic self-incompatibility, whereas the genotype of the sporophytic tissue in sporophytic self-compatibility determines the incompatibility process.
Gametophytic and sporophytic self-incompatibility are major self-incompatibility that occur in plants. The S locus determines them.
Key Areas Covered
1. What is Self Incompatibility
– Definition, Facts, Importance
2. What is Gametophytic Self Incompatibility
– Definition, Facts, Importance
3. What is Sporophytic Self Incompatibility
– Definition, Facts, Importance
4. Similarities Between Gametophytic and Sporophytic Self Incompatibility
– Outline of Common Features
4. Difference Between Gametophytic and Sporophytic Self Incompatibility
– Comparison of Key Differences
Key Terms
Gametophytic Self Incompatibility, Sporophytic Self Incompatibility
What is Self Incompatibility
Self-incompatibility is a collective name for the several genetic mechanisms that prevent self-fertilization. It occurs in sexually reproducing organisms. The key feature of self-incompatibility encourages outcrossing and allogamy. It is particularly common in flowering plants. It is also present in other groups, including fungi and sea squirts. When the pollen grain reaches the stigma of the same or another plant with a matching allele, a series of reactions occur inside the flower. They include the process of pollen germination, pollen-tube growth, ovule fertilization, and embryo development. As a result, no seeds are produced. Self-incompatibility prevents inbreeding. Simultaneously, it promotes the generation of new genotypes in plants. Further, it is considered one of the causes of the success of angiosperms on Earth. However, the most common mechanisms of self-incompatibility in plants include pollen germination or stigma and the pollen tube elongation in the style.
Figure 1: Gametophytic Self Incompatibility
Furthermore, a single locus called S locus controls the mechanisms of self-incompatibility. Also, these mechanisms are based on protein-protein interactions. Therefore, the S locus contains two basic protein-coding regions. One is expressed in the pistil, while the other is expressed in the anther. The two regions occur in close proximity, and therefore, they are genetically linked. Also, the two proteins interact to arrest pollen germination or pollen tube elongation.
What is Gametophytic Self Incompatibility
Gametophytic self-incompatibility is a mechanism of self-incompatibility in which the male gametophyte determines the self-incompatibility in plants. Male gametophyte is the sexual phase of the plant produced from the pollen grain.
Figure 2: Sporophytic Self Incompatibility
What is Sporophytic Self Incompatibility
Sporophytic self-incompatibility is the other mechanism of self-incompatibility in which the sporophyte of the pollen grain determines the self-incompatibility in plants. Sporophyte is a multicellular, spore-producing phase that starts from a diploid zygote. Also, it produces haploid spores by mitotic division.
Similarities Between Gametophytic and Sporophytic Self Incompatibility
- Gametophytic and sporophytic self-incompatibility are two major self-incompatibility that occur in plants.
- S locus determines both self-incompatibilities.
Difference Between Gametophytic and Sporophytic Self Incompatibility
Definition
Gametophytic self-incompatibility refers to the inability of the gametes from the same parent plant to fuse and form a zygote or, if the zygote forms, it fails to develop. In contrast, sporophytic self-incompatibility refers to a self-pollen recognition system that enforces outcrossing in plants.
Determination of the Self-Incompatibility
The incompatibility process is determined by the genotype of male gametophyte in gametophytic self-incompatibility, while the genotype of the sporophytic tissue in sporophytic self-compatibility determines the incompatibility process.
Occurrence
Gametophytic self-incompatibility is common in two-celled pollen, while sporophytic self-incompatibility is common in three-celled pollen.
In Vitro Germination
In vitro germination is easy in gametophytic self-incompatibility, while in vitro germination is difficult in sporophytic self-incompatibility.
Conclusion
In brief, gametophytic and sporophytic self-incompatibility are two major self-incompatibility methods in plants. S locus determines both types of self-incompatibilities. The genotype of male gametophyte determines gametophytic self-incompatibility. It is common in two-celled pollen. Also, in vitro germination is easy in gametophytic self-incompatibility. In comparison, sporophytic self-incompatibility is determined by the genotype of the sporophytic tissue. However, it is common in two-celled pollen. Additionally, in vitro germination is difficult in sporophytic self-compatibility. Therefore, the main difference between gametophytic and sporophytic self-incompatibility is their determination.
References:
- PLS 622: Plant Physiology I, Friday, October 20, 2006 reproductive development:. Plant Physiology I. (n.d.).
Image Courtesy:
- “Clivia miniata, pollen tube” By Micropix – Own Work (CC-BY SA 3.0) via Commons Wikimedia
- “Auto-incompatibilité gamétophytique” By Primroses32 – Own Work (CC-BY SA 4.0) via Commons Wikimedia
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