Parthenocarpy

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Seedless watermelon Watermelon seedless.jpg
Seedless watermelon

In botany and horticulture, parthenocarpy is the natural or artificially induced production of fruit without fertilisation of ovules, which makes the fruit seedless. The phenomenon has been observed since ancient times [1] but was first scientifically described by German botanist Fritz Noll in 1902. [2]

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Stenospermocarpy may also produce apparently seedless fruit, but the seeds are actually aborted while they are still small. Parthenocarpy (or stenospermocarpy) occasionally occurs as a mutation in nature; if it affects every flower, the plant can no longer sexually reproduce [ citation needed ] but might be able to propagate by apomixis or by vegetative means. Examples of this include many citrus varieties that undergo nucellar embryony for reproduction, instead of solely sexual reproduction, and can yield seedless fruits.

Ecological importance

Parthenocarpy of some fruits on a plant may be of value. Up to 20% of the fruits of wild parsnip are parthenocarpic. The seedless wild parsnip fruit are preferred by certain herbivores and so serve as a "decoy defense" against seed predation. [3] Utah juniper has a similar defense against bird feeding. [4] The ability to produce seedless fruit when pollination is unsuccessful may be an advantage to a plant because it provides food for the plant's seed dispersers. Without a fruit crop, the seed dispersing animals may starve or migrate.

In some plants, pollination or another stimulation is required for parthenocarpy, termed stimulative parthenocarpy. Plants that do not require pollination or other stimulation to produce parthenocarpic fruit have vegetative parthenocarpy. Seedless cucumbers are an example of vegetative parthenocarpy, seedless watermelon is an example of stenospermocarpy as they are immature seeds (aborted ones).

Plants that moved from one area of the world to another may not always be accompanied by their pollinating partner, and the lack of pollinators has spurred human cultivation of parthenocarpic varieties.

Commercial importance

Seedlessness is seen as a desirable trait in edible fruit with hard seeds such as banana, pineapple, orange and grapefruit. Parthenocarpy is also desirable in fruit crops that may be difficult to pollinate or fertilize, such as fig, tomato and summer squash. In dioecious species, such as persimmon, parthenocarpy increases fruit production because staminate trees do not need to be planted to provide pollen. Parthenocarpy is undesirable in nut crops, such as pistachio, for which the seed is the edible part. Horticulturists have selected and propagated parthenocarpic cultivars of many plants, including banana, fig, cactus pear ( Opuntia ), breadfruit and eggplant. Some plants, such as pineapple, produce seedless fruits when a single cultivar is grown because they are self-infertile. Some cucumbers produce seedless fruit if pollinators are excluded. Strange as it seems, seedless watermelon plants are grown from seeds. The seeds are produced by crossing a diploid parent with a tetraploid parent to produce triploid seeds. It has been suggested that Cannabis could explain the difference in the plant's yields in active compounds. [5]

Some parthenocarpic cultivars are of ancient origin. The oldest known cultivated plant is a parthenocarpic fig that was first grown at least 11,200 years ago. [6]

In some climates, normally-seeded pear cultivars produce mainly seedless fruit for lack of pollination. [7]

When sprayed on flowers, any of the plant hormones gibberellin, auxin and cytokinin could stimulate the development of parthenocarpic fruit. That is termed artificial parthenocarpy. Plant hormones are seldom used commercially to produce parthenocarpic fruit. Home gardeners sometimes spray their tomatoes with an auxin to assure fruit production. [8]

Some parthenocarpic cultivars have been developed as genetically modified organisms. [9] [10]

Misconceptions

Related Research Articles

<span class="mw-page-title-main">Fruit</span> Seed-bearing part of a flowering plant

In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.

<span class="mw-page-title-main">Rambutan</span> Southeast Asian fruit

Rambutan is a medium-sized tropical tree in the family Sapindaceae. The name also refers to the edible fruit produced by this tree. The rambutan is native to Southeast Asia. It is closely related to several other edible tropical fruits, including the lychee, longan, pulasan, and quenepa.

<span class="mw-page-title-main">Apomixis</span> Replacement of the normal sexual reproduction by asexual reproduction, without fertilization

In botany, apomixis is asexual development of seed or embryo without fertilization. However, other definitions include replacement of the seed by a plantlet or replacement of the flower by bulbils.

<span class="mw-page-title-main">Clementine</span> Hybrid citrus fruit

A clementine is a tangor, a citrus fruit hybrid between a willowleaf mandarin orange and a sweet orange, named in honor of Clément Rodier, a French missionary who first discovered and propagated the cultivar in Algeria. The exterior is a deep orange colour with a smooth, glossy appearance. Clementines can be separated into 7 to 14 segments. Similar to tangerines, they tend to be easy to peel. They are typically juicy and sweet, with less acid than oranges. Their oils, like other citrus fruits, contain mostly limonene as well as myrcene, linalool, α-pinene and many complex aromatics.

<span class="mw-page-title-main">Fruit tree</span> Tree which bears fruit

A fruit tree is a tree which bears fruit that is consumed or used by animals and humans — all trees that are flowering plants produce fruit, which are the ripened ovaries of flowers containing one or more seeds. In horticultural usage, the term "fruit tree" is limited to those that provide fruit for human food. Types of fruits are described and defined elsewhere, but would include "fruit" in a culinary sense, as well as some nut-bearing trees, such as walnuts.

<span class="mw-page-title-main">Cucumber</span> Species of flowering plant that produces cucumbers

The cucumber is a widely-cultivated creeping vine plant in the family Cucurbitaceae that bears cylindrical to spherical fruits, which are used as culinary vegetables. Considered an annual plant, there are three main types of cucumber—slicing, pickling, and seedless—within which several cultivars have been created. The cucumber originates from the Himalayas, China, and Northern Thailand, but now grows on most continents, and many different types of cucumber are grown commercially and traded on the global market. In North America, the term wild cucumber refers to plants in the genera Echinocystis and Marah, though the two are not closely related.

<span class="mw-page-title-main">Fruit tree pollination</span>

Pollination of fruit trees is required to produce seeds with surrounding fruit. It is the process of moving pollen from the anther to the stigma, either in the same flower or in another flower. Some tree species, including many fruit trees, do not produce fruit from self-pollination, so pollinizer trees are planted in orchards.

<span class="mw-page-title-main">Vegetative reproduction</span> Asexual method of reproduction in plants

Vegetative reproduction is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or specialized reproductive structures, which are sometimes called vegetative propagules.

<span class="mw-page-title-main">Auxin</span> Plant hormone

Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essential for plant body development. The Dutch biologist Frits Warmolt Went first described auxins and their role in plant growth in the 1920s. Kenneth V. Thimann became the first to isolate one of these phytohormones and to determine its chemical structure as indole-3-acetic acid (IAA). Went and Thimann co-authored a book on plant hormones, Phytohormones, in 1937.

<i>Cannabis sativa</i> Plant species

Cannabis sativa is an annual herbaceous flowering plant indigenous to Eastern Asia, but now of cosmopolitan distribution due to widespread cultivation. It has been cultivated throughout recorded history, used as a source of industrial fiber, seed oil, food, recreation, religious and spiritual moods and medicine. Each part of the plant is harvested differently, depending on the purpose of its use. The species was first classified by Carl Linnaeus in 1753. The word sativa means "things that are cultivated."

<span class="mw-page-title-main">Stenospermocarpy</span> Biological mechanism

Stenospermocarpy is the biological mechanism that produces parthenocarpy (seedlessness) in some fruits, notably many table grapes.

<span class="mw-page-title-main">Gibberellic acid</span> Chemical compound

Gibberellic acid (also called gibberellin A3 or GA3) is a hormone found in plants and fungi. Its chemical formula is C19H22O6. When purified, it is a white to pale-yellow solid.

A seedless fruit is a fruit developed to possess no mature seeds. Since eating seedless fruits is generally easier and more convenient, they are considered commercially valuable.

Plant reproduction is the production of new offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from either parent. Asexual reproduction produces new individuals without the fusion of gametes, resulting in clonal plants that are genetically identical to the parent plant and each other, unless mutations occur.

<span class="mw-page-title-main">Nucellar embryony</span>

Nucellar embryony is a form of seed reproduction that occurs in certain plant species, including many citrus varieties. Nucellar embryony is a type of apomixis, where eventually nucellar embryos from the nucellus tissue of the ovule are formed, independent of meiosis and sexual reproduction. During the development of seeds in plants that possess this genetic trait, the nucellus tissue which surrounds the megagametophyte can produce nucellar cells, also termed initial cells. These additional embryos (polyembryony) are genetically identical to the parent plant, rendering them as clones. By contrast, zygotic seedlings are sexually produced and inherit genetic material from both parents. Most angiosperms reproduce sexually through double fertilization. Different from nucellar embryony, double fertilization occurs via the syngamy of sperm and egg cells, producing a triploid endosperm and a diploid zygotic embryo. In nucellar embryony, embryos are formed asexually from the nucellus tissue. Zygotic and nucellar embryos can occur in the same seed (monoembryony), and a zygotic embryo can divide to produce multiple embryos. The nucellar embryonic initial cells form, divide, and expand. Once the zygotic embryo becomes dominant, the initial cells stop dividing and expanding. Following this stage, the zygotic embryo continues to develop and the initial cells continue to develop as well, forming nucellar embryos. The nucellar embryos generally end up outcompeting the zygotic embryo, rending the zygotic embryo dormant. The polyembryonic seed is then formed by the many adventitious embryos within the ovule. The nucellar embryos produced via apomixis inherit its mother's genetics, making them desirable for citrus propagation, research, and breeding.

<i>Musa acuminata</i> Species of banana native to Southeast Asia

Musa acuminata is a species of banana native to Southern Asia, its range comprising the Indian Subcontinent and Southeast Asia. Many of the modern edible dessert bananas are from this species, although some are hybrids with Musa balbisiana. First cultivated by humans around 10 kya, it is one of the early examples of domesticated plants.

Pseudogamy refers to aspects of reproduction. It has different meanings in zoology and in botany.

<i>Opuntia</i> Genus of cactus

Opuntia, commonly called the prickly pear cactus, is a genus of flowering plants in the cactus family Cactaceae, many known for their flavorful fruit and showy flowers. Prickly pear alone is more commonly used to refer exclusively to the fruit, but may also be used for the plant itself; in addition, other names given to the plant and its specific parts include tuna (fruit), sabra, nopal from the Nahuatl word nōpalli, nostle (fruit) from the Nahuatl word nōchtli, and paddle cactus. The genus is named for the Ancient Greek city of Opus, where, according to Theophrastus, an edible plant grew and could be propagated by rooting its leaves. The most common culinary species is the Indian fig opuntia (O. ficus-indica).

<span class="mw-page-title-main">Fig</span> Species of flowering plant known as the common fig

The fig is the edible fruit of Ficus carica, a species of small tree in the flowering plant family Moraceae, native to the Mediterranean region, together with western and southern Asia. It has been cultivated since ancient times and is now widely grown throughout the world. Ficus carica is the type species of the genus Ficus, containing over 800 tropical and subtropical plant species.

<span class="mw-page-title-main">Ethylene (plant hormone)</span> Alkene gas naturally regulating the plant growth

Ethylene (CH
2
=CH
2
) is an unsaturated hydrocarbon gas (alkene) acting as a naturally occurring plant hormone. It is the simplest alkene gas and is the first gas known to act as hormone. It acts at trace levels throughout the life of the plant by stimulating or regulating the ripening of fruit, the opening of flowers, the abscission (or shedding) of leaves and, in aquatic and semi-aquatic species, promoting the 'escape' from submergence by means of rapid elongation of stems or leaves. This escape response is particularly important in rice farming. Commercial fruit-ripening rooms use "catalytic generators" to make ethylene gas from a liquid supply of ethanol. Typically, a gassing level of 500 to 2,000 ppm is used, for 24 to 48 hours. Care must be taken to control carbon dioxide levels in ripening rooms when gassing, as high temperature ripening (20 °C; 68 °F) has been seen to produce CO2 levels of 10% in 24 hours.

References

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