Polyembryony

What Is Polyembryony?

A very interesting phenomenon in plants occurs in which a single seed or ovule gives rise to several embryos. This process has great implications for plant reproduction, agriculture, and plant development studies. Polyembryony helps to understand the plasticity and adaptability of a species of plant.

Polyembryony Definition

Polyembryony is the development of two or more embryos in a single seed or ovule. The process can be induced artificially in vitro culture, but it also occurs in some plant species. The features of such a phenomenon include duads and/or triads:

More than one embryo develops from a single seed or ovule, forming genetically different individuals.

Characteristics Of Polyembryony

Gene Variation: Depending on their origin, the polyembryony might finally lead to genetic variation among the resultant embryos. Asexual Reproduction: In a way, polyembryony can be seen as falling under the category of asexual reproduction because this process makes it possible for an organism to produce offspring that are genetically identical without using gametes. Importance in Agriculture: There are many uses of polyembryony in agriculture, especially in clonal planting material production and cultivar development.

Types Of Polyembryony

Polyembryony can result through different mechanisms, leading to the formation of multiple embryos within a single seed or ovule:

Zygotic Polyembryony

In zygotic polyembryony, the division of the zygote leads to the formation of two or more embryos that result in genetically identical individuals.

This kind of polyembryony is frequent in citrus fruits and in some other plant species.

Nucellar Polyembryony

Nucellar polyembryony consists of the development of embryos from the nucellar tissue surrounding the embryo sac.

These embryos are genetically identical to the maternal plant since they originate from somatic cells.

Nucellar polyembryony is found in numerous plants of citrus fruits, mango, and a few other tropical and subtropical plants.

Adventitious Polyembryony

Adventitious embryony occurs when additional embryos develop from the remaining parts of the ovule, such as the integuments or the suspensor.

These embryos may or may not be genetically identical to the primary embryo or amongst each other.

Examples of plants with this type of polyembryony are some orchids and ferns.

Polyembryony importance

Asexual Reproduction: One of the most important advantages of this phenomenon is that polyembryony enables the generation of offspring with similar genetic materials. This aspect can, therefore, be utilised in crops for the propagation of identical genomes carrying desirable features.

Genetic Diversity: Still, on occasions, polyembryony may lead to variations between the formed embryos, hence offering the advantages of adaptation to plant species.

Embryological Studies: Polyembryony offers scope for the studies of plant embryology and the mechanisms of development of embryos.

Crop Improvement: The knowledge of polyembryony can be utilised to create new crop forms with such deliberated characteristics as high yield or disease resistance.

Problems and Limitations

Unequal Development: In some cases, the several embryos included in a seed or ovule may not be equally developed, and consequently may be of different sizes and very unequal in vigour.

Low Seed Viability: This polyembryony may sometimes depress the overall viability of seeds because the seed's resources are divided among the many embryos.

Difficulty of Identification: Genetically different embryos are hard to distinguish from clonal ones, especially in the early stages of development.

Conclusion

This is a remarkable capability of plants, where some embryos can be derived from a single seed or even an ovule. The present knowledge regarding the types and mechanisms behind polyembryony offers very valuable information in the area of reproduction and development in plants, which can be further extrapolated to possible agricultural and horticultural applications. Research in this field could thus be used in breeding better varieties of crops and also in the much-needed successful propagation of crops.

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