What is Apomixis, and What is its Importance?
What is Apomixis?
Apomixis (asexual seed formation) occurs when a plant develops the ability to avoid the most basic aspects of sexual reproduction: meiosis and fertilization. The resulting seed germinates a plant that grows as a maternal clone without the need for male fertilization.
Apomixis is a type of reproduction that is characterized by the formation of gametes (ova and spermatozoa) via mitotic cell division. This means it does not use meiosis to form the sex cells. Apomixis is also called “parthenogenesis” or “agamogenesis.” Apomixis is a form of parthenogenesis in which the ova (eggs) are formed without a male parent’s presence.
Asexual reproduction is a type of reproduction where the offspring are genetically identical to the parent, and it is known as apomixis. There are various forms of apomixis, but they all involve at least one generation in which there is no meiosis or fertilization.
The importance of these reproduction types to plants is that they allow for rapid cloning and forming new plant cultivars solely from genetic material. This is one of the ways that plants can quickly adapt to and evolve in new environments.
Without this sort of reproduction, it could be difficult for a species to keep up with its competitors in a changing environment. Plants naturally reproduce by the process of vegetative propagation.
Vegetative reproduction is when a transplanted plant produces more immature seeds (called cotyledons or seedlings) than mature seeds capable of germination.
While this method is resource-efficient, it is not very reliable as the resulting new plant might not be fertile or have the desired characteristics of the plant you are trying to grow. Apomixis makes reproduction more reliable.
While no major seed crops have been shown to be capable of apomixis, this drastic change in the reproductive process has been recorded in many flowering plant species. The ability to produce maternal clones and, as a result, quickly repair desirable genotypes in crop species could speed up agricultural breeding strategies.
The potential of apomixis as a next-generation breeding technology has intensified interest in the mechanisms that regulate apomixis.
What are some types of apomixis?
There are two important types of apomixis in plants. They are external and internal apomixis. External apomixis involves the use of tissue other than the flower to produce seeds. This tissue can be a branch or leaf that is regenerated after the parent plant produces flowers.
Internal apomixis is when there is no modification to the physical structure of the parent plant. Instead, a mutation occurs in the reproductive cells, such as in an egg or sperm cell or during meiosis, resulting in an embryo with new genetic material.
Importance of Apomixis in Plant Breeding
Apomixis is a mechanism for seed development that does not involve meiosis or syngamy. It is crucial in the development of hybrid seeds. Farmers face high costs when growing hybrid seeds through cultivation. Apomixis avoids the loss of unique hybrid characteristics.
- Since seeds are produced without reduction division and fertilization, the desirable characteristics are not segregated (separated).
- Superior and desirable characteristics can be passed down across generations.
- Apomixis is extremely beneficial in the commercial hybrid seed production process.
The cultivation of hybrid seeds is very expensive.
- If apomixis reproduction continues, farmers will use these hybrid seeds to grow crops year after year, eliminating the need to purchase hybrid seeds every year.
Examples of Apomixis
Apomixis is the process of the formation of new individuals without fertilization. Examples of apomixis can be found in genera like Crataegus, Amelanchier, and Sorbus, which are all types of plants that have this type of reproduction system.
Asexual reproduction in plants is called apomixis. It most often occurs when a plant produces offspring without fertilization because the egg cell or embryo comes from an unfertilized ovule. Apomixis is interesting for many reasons, but it has particular importance as a tool to help propagate rare and endangered species of plants.
Advantages & Disadvantages of Apomixis in Plant Breeding
– The risk of genetic problems is reduced because there are no sperm cells to introduce new, random mutations. One problem with apomictic plants can be that they lack vigor and grow more slowly than sexually reproduced ones.
– There is a higher chance for the desired trait (genotype) to be passed on when selecting parents from an apomictic population as opposed to relying upon sexual reproduction where it may not always happen due to cross pollination or other means.
This helps maintain purity within the species, make them become better adapted over time by generating more offspring which carry those favorable traits and also allows propagation without seeds or pollen being necessary. For endangered or threatened species, it is possible to use apomixis for propagation without even being able to find any plants of that particular type.
– The disadvantages are generally the same as sexually reproduced organisms but with some different consequences such as uniformity within a population which can cause problems when an organism’s environment changes and they need diversity in their gene pool.
– Apomictic reproduction also reduces genetic variation by only passing on one parent’s set of genes while sexual reproduction creates two copies so there would be more possibilities for mutations or accidents resulting in better chances of survival if something happens to affect this individual plant’s ability to reproduce because its other copy will still exist elsewhere in the world.
How is apomixis used in breeding new cultivars?
Apomixis is useful because it allows for creating new cultivars that are exact genetic copies of the parent plant. It is used when the breeder wants to prevent the mixing of pollen from different plants or when they want to make sure offspring are produced from a particular individual.
This also allows for rapid clonal reproduction so that desirable traits can spread through a population quickly.
How does apomixis occur in plants?
As mentioned above, there are two main types of apomixis in plants: external and internal. There is a mutation of the reproductive cells that results in an embryo with new genetic material in both cases.
In the case of external apomixis, a new plant will grow where the reproductive material was produced, and it will be a genetically identical copy of the parent plant. In the case of internal apomixis, an embryo is produced that is a genetically identical copy of the parent plant.
This can be done by either growing many seeds and selecting the desired traits in the resulting plants or growing a single seed and backcrossing it with its parent (this is essentially the same process as hybrid breeding).
What are some examples of apomictic plants?
Many different kinds of plants reproduce in a variety of different ways that are classified as apomixis. Many of the flowers and herbs contain pollen that spreads to other plants or animals and will then grow into new plant varieties. One example is the labiate (i.e., nosegays) plants such as butomus.
These have flowers with many different types of pollination vectors, such as bees and beetles. These plants can also be self-pollinating. This means that pollen from the same plant can fertilize the ovules in its own flower.
Apomixis is a type of asexual reproduction used by many kinds of plants to produce new cultivars or varieties without using sexual reproduction, which requires mixing different individuals to create new combinations of genes.
It is most easily done via internal apomixis, but external apomixis can also occur. External apomixis uses a branch or leaf that is regenerated after the parent plant produces flowers.
Internal apomixis involves a mutation of the reproductive cells, such as in an egg or sperm cell or during meiosis, resulting in an embryo with new genetic material.