What In Botany Is Polyembryony?

Polyembryony is the production of two or more than two embryos from a single seed or fertilized egg in plants. This phenomenon occurs either due to the fertilization of one or more embryonic sacs or the origination of embryos outside of the sac. Polyembryony is a unique form of asexual reproduction where multiple offspring are produced from a single egg or zygote. It is a common phenomenon in plants, where two or more embryos develop from a single fertilized egg, forming what in humans is known as identical twins.

Polyembryony was discovered by Leeuwenhoek in 1729 in Orange and is a developmental mode where a single egg gives rise to multiple, genetically-identical offspring. Sporadic polyembryony is a very widespread reproductive phenomenon that produces more than one plant per seed in maize and other species. Polyembryony refers to the growth of more than one embryo in a single ovary, seed, or complete fertilization of a fertilized egg.

The occurrence of more than one embryo (from a single fertilized egg) in a seed is called polyembryony. The phenomenon was first observed in orange seeds by Antony von Neumann. Polyembryony is the process of producing two or more embryos from a single seed or fertilized egg, which are indistinguishable from one another.

In summary, polyembryony is a unique form of asexual reproduction in plants, where multiple embryos develop from a single fertilized egg or zygote. This phenomenon is a common and widespread phenomenon in plants, with the occurrence of more than one seed per seed being a significant factor in its development.

What are the three types of cleavage?

Cleavage is the division of cells in embryology, occurring in the early development of the embryo after fertilization. It involves rapid cell cycles, producing a cluster of cells the same size as the original zygote. The cells derived from cleavage are called blastomeres and form a compact mass called the morula. Cleavage ends with the formation of the blastula or blastocyst in mammals. The cleavage can be holoblastic (total or entire cleavage) or meroblastic (partial cleavage).

The egg with the highest concentration of yolk is called the vegetal pole, while the opposite is the animal pole. Cleavage increases the number of cells and nuclear mass without increasing the cytoplasmic mass, resulting in an increase in the ratio of nuclear to cytoplasmic material.

What is the role of polyembryony in plant breeding?

Polyembryony is a crucial property in horticulture, ensuring genetic similarity between seedlings and parents and preventing disease during the growing process. It is not limited to plants but also helps in reproduction. Antoni van Leeuwenhoek discovered polyembryony in orange seeds for the first time. Gymnosperms have a high frequency of polyembryony, with women gametophytes developing two or more arches in their reproductive organs. The presence of multiple archegoniums results in fertilization of two or more eggs, forming two or more possible embryos.

Simple polyembryony, discovered in Cycas Circinalis by A. N. Rao, occurs infrequently in this category. Understanding polyembryony, its types, occurrences, and significance is essential for a better understanding of plants and their role in reproduction.

What is cleavage polyembryony botany?

Gymnosperms typically have a single embryo in the seed, but sometimes multiple embryos develop in a single seed. This is called polyembryony, where the original zygote splits into many identical embryos. Cleavage polyembryony is a common feature in gymnosperms and can occur in angiosperms, but it is rare. Monocotyledons and dicotyledons are two types of angiosperm plants, with monocots having a single cotyledon, fibrous root system, and parallel venation leaves, and dicots having a pair of cotyledons, taproot system, and reticulate or net venation leaves.

What is apomixis and polyembryony in plants?

Apomixis is an asexual reproduction method where seeds are produced without fertilization, mimicking sexual reproduction. It can occur through diploid egg cell formation without meiosis or reduction division, which develops into an embryo. Offspring produced by apomixis are genetically identical to parents, as fertilization does not occur. There are two main types of apomixis, depending on the tissue involved, and it can occur in various ways, such as meiosis or reduction division.

What is polyembryony and its example?

Polyembryony occurs when more than one embryo in a seed occurs due to the formation of multiple eggs in the embryo sac. This process can also involve the development of nucellus cells. Examples of such embryos include orange lemon, groundnut, mango, and onion.

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In which plant polyembryony commonly occurs?

The correct answer is C, Citrus, which exhibits polyembryony, a trait wherein multiple embryos are present within the seed. This phenomenon is more prevalent in gymnosperms than in angiosperms. This phenomenon is observed in a limited number of cases, including in citrus fruits and mangoes. In the case of Citrus, up to 10 nucellar embryos are formed from external structures, a phenomenon known as adventive polyembryony.

What is the difference between Parthenocarpy and polyembryony?

Parthenocarpy allows early fruit production and harvest, enhancing fruit quality and yield in plant species. Polyembryony, also known as embryonic cloning, is an asexual reproduction method where a single egg or zygote produces multiple offspring, genetically identical but separate from their parents. This method can rationalize and increase fruit yield in plant species grown for their fruits.

Is Mango an example of polyembryony?

Mango, like citrus, has both monoembryonic and polyembryonic seed types. Mangoes from Southeast Asia are typically polyembryonic, while those from the Myanmar-Indochinese region are typically monoembryonic. In mango breeding programs, monoembryonic varieties are used as maternal parents to create hybrids derived from the zygotic embryo. The polyembryony trait is the basis of most mango rootstocks, as it can be propagated through seeds that produce multiple maternal clones without grafting.

The polyembryonic trait segregates in both mango and citrus as a single dominant Mendelian trait. The citrus CitRWP gene has been identified as causing polyembryony, and overexpression of one of these genes promotes ectopic embryogenesis in somatic tissues.

Mango, developed from two centers of origin in South East Asia and North East India, is one of the most important fruit crops, with an annual production of more than 57 million tons and second only to banana among tropical and subtropical fruits. However, the biology of mango is understudied due to the lack of genetic and genomic resources. Recently, several genomic tools for mango have been created, including transcriptome data, two detailed genetic maps, and genome sequence drafts. Mango is a true diploid with a genome size of ~400-440 Mbps and is believed to have undergone WGD events around 70 million years ago.

Is mango an example of polyembryony?

Sexual reproduction in plants is the primary pathway for creating new genetic combinations in modern agriculture. In heterozygous plants, vegetative propagation (cloning) is the primary path to create genetically uniform plants. Apomixis is another natural plant mechanism that creates genetically uniform plants (clones). In fruit crops like citrus and mango, sporophytic apomixis results in polyembryony, where seeds contain multiple embryos, one of which is sexually originated and the others are vegetative clones of the parent mother tree.

The study identified MiRWP as the gene that causes polyembryony in mango, with a strong correlation between a specific insertion in the gene’s promoter region and altered expression in flowers and developing fruitlets, inducing multiple embryos.

The results suggest convergent evolution of polyembryony in the two species. Further work is required to demonstrate the utility of these genes (mango and citrus) in other biological systems as a tool for the clonal production of other crops. Vegetative (asexual) reproduction is needed to propagate genetically identical individuals (clones) in heterozygous plant systems. Most agricultural practices for creating clones in fruit trees, some forest trees, and numerous other species are based on vegetative propagation through cuttings, rooting, grafting, and tissue culture.

Apomixis is an asexual reproductive strategy naturally found in some angiosperms, defined as asexual reproduction through seeds that leads to the production of clonal progeny whose genotype is identical to that of the mother plant. Apomixis mechanisms in seeds are subdivided into gametophytic or sporophytic, depending on whether the embryo develops via a gametophyte (embryo sac) or directly from diploid somatic tissues (sporophytic).

However, apomixis is rarely used for agricultural purposes, and manipulation of apomixis in different crops may provide an alternative way to propagate plants and form an alternative to hybrid seed production.

What is an example of apomixis?

Apomictic plants, which are genetically identical from one generation to the next, have some of the characteristics of true species, maintaining distinctions from other lineages within the same genus. These lineages are often called microspecies, and in some genera, hundreds or thousands of microspecies can be identified and named. Examples of apomixis can be found in the genera Crataegus, Amelanchier, Sorbus, Rubus, Poa, Nardus stricta, Hieracium, and Taraxacum.

Apomixis is reported to occur in about 10 of globally extant ferns and has evolved several times independently in three different clades. Although sexual reproduction is lost, apomixis can pass along traits fortuitous for evolutionary fitness. Facultative apomixis does not prevent variation but multiplies certain varietal products. The apomicts discovered the effectiveness of mass production long before Henry Ford applied it to the production of the automobile.

What is the difference between simple polyembryony and cleavage polyembryony?

Gymnosperms have two types of polyembryony: simple polyembryony, where multiple embryos form from fertilization of archegonia in a gametophyte, and cleavage polyembryony, where multiple embryos arise from the splitting of embryonal cells of a single zygote. Both types occur in gymnosperms. The copyright for this information belongs to Elsevier B. V., its licensors, and contributors, and all rights are reserved for text and data mining, AI training, and similar technologies.