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Reproduction is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. There are two forms of reproduction: asexual and sexual.
Fertilisation or fertilization, also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a zygote and initiate its development into a new individual organism or offspring. While processes such as insemination or pollination, which happen before the fusion of gametes, are also sometimes informally referred to as fertilisation, these are technically separate processes. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms, the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation.
Self-pollination is a form of pollination in which pollen from one plant arrives at the stigma of a flower or at the ovule of the same plant. The term cross-pollination is used for the opposite case, where pollen from one plant moves to a different plant.
Plant reproductive morphology is the study of the physical form and structure of those parts of plants directly or indirectly concerned with sexual reproduction.
Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms, and thus encourage outcrossing and allogamy. It is contrasted with separation of sexes among individuals (dioecy), and their various modes of spatial (herkogamy) and temporal (dichogamy) separation.
Heterostyly is a unique form of polymorphism and herkogamy in flowers. In a heterostylous species, two or three morphological types of flowers, termed "morphs", exist in the population. On each individual plant, all flowers share the same morph. The flower morphs differ in the lengths of the pistil and stamens, and these traits are not continuous. The morph phenotype is genetically linked to genes responsible for a unique system of self-incompatibility, termed heteromorphic self-incompatibility, that is, the pollen from a flower on one morph cannot fertilize another flower of the same morph.
Sequential hermaphroditism is one of the two types of hermaphroditism, the other type being simultaneous hermaphroditism. It occurs when the organism's sex changes at some point in its life. A sequential hermaphrodite produces eggs and sperm at different stages in life. Sequential hermaphroditism occurs in many fish, gastropods, and plants. Species that can undergo these changes do so as a normal event within their reproductive cycle, usually cued by either social structure or the achievement of a certain age or size. In some species of fish, sequential hermaphroditism is much more common than simultaneous hermaphroditism.
Geitonogamy is a type of self-pollination. Geitonogamous pollination is sometimes distinguished from the fertilizations that can result from it, geitonogamy. If a plant is self-incompatible, geitonogamy can reduce seed production.
Crepis, commonly known in some parts of the world as hawksbeard or hawk's-beard, is a genus of annual and perennial flowering plants of the family Asteraceae superficially resembling the dandelion, the most conspicuous difference being that Crepis usually has branching scapes with multiple heads. The genus name Crepis derives from the Greek krepis, meaning "slipper" or "sandal", possibly in reference to the shape of the fruit.
Allogamy or cross-fertilization is the fertilization of an ovum from one individual with the spermatozoa of another. By contrast, autogamy is the term used for self-fertilization. In humans, the fertilization event is an instance of allogamy. Self-fertilization occurs in hermaphroditic organisms where the two gametes fused in fertilization come from the same individual. This is common in plants and certain protozoans.
A flower, also known as a bloom or blossom, is the reproductive structure found in flowering plants. Flowers consist of a combination of vegetative organs – sepals that enclose and protect the developing flower, petals that attract pollinators, and reproductive organs that produce gametophytes, which in flowering plants produce gametes. The male gametophytes, which produce sperm, are enclosed within pollen grains produced in the anthers. The female gametophytes are contained within the ovules produced in the carpels.
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.
Tristyly is a rare floral polymorphism that consists of three floral morphs that differ in regard to the length of the stamens and style within the flower. This type of floral mechanism is thought to encourage outcross pollen transfer and is usually associated with heteromorphic self-incompatibility to reduce inbreeding. It is an example of heterostyly and reciprocal herkogamy, like distyly, which is the more common form of heterostyly. Darwin first described tristylous species in 1877 in terms of the incompatibility of these three morphs.
Androdioecy is a reproductive system characterized by the coexistence of males and hermaphrodites. Androdioecy is rare in comparison with the other major reproductive systems: dioecy, gynodioecy and hermaphroditism. In animals, androdioecy has been considered a stepping stone in the transition from dioecy to hermaphroditism, and vice versa.
Gynodioecy is a rare breeding system that is found in certain flowering plant species in which female and hermaphroditic plants coexist within a population. Gynodioecy is the evolutionary intermediate between hermaphroditism and dioecy.
Autogamy or self-fertilization refers to the fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a reproductive mechanism employed by many flowering plants. However, species of protists have also been observed using autogamy as a means of reproduction. Flowering plants engage in autogamy regularly, while the protists that engage in autogamy only do so in stressful environments.
The monocots are one of the two major groups of flowering plants, the other being the dicots. In order to reproduce they utilize various strategies such as employing forms of asexual reproduction, restricting which individuals they are sexually compatible with, or influencing how they are pollinated. Nearly all reproductive strategies that evolved in the dicots have independently evolved in monocots as well. Despite these similarities and their close relatedness, monocots and dicots have distinct traits in their reproductive biologies.
Sexual selection in Arabidopsis thaliana is a mode of natural selection by which the flowering plant Arabidopsis thaliana selects mates to maximize reproductive success.
A mixed mating system, also known as “variable inbreeding” a characteristic of many hermaphroditic seed plants, where more than one means of mating is used. Mixed mating usually refers to the production of a mixture of self-fertilized (selfed) and outbred (outcrossed) seeds. Plant mating systems influence the distribution of genetic variation within and among populations, by affecting the propensity of individuals to self-fertilize or cross-fertilize . Mixed mating systems are generally characterized by the frequency of selfing vs. outcrossing, but may include the production of asexual seeds through agamospermy. The trade offs for each strategy depend on ecological conditions, pollinator abundance and herbivory and parasite load. Mating systems are not permanent within species; they can vary with environmental factors, and through domestication when plants are bred for commercial agriculture.
Cryptic self-incompatibility (CSI) is the botanical expression that's used to describe a weakened self-incompatibility (SI) system. CSI is one expression of a mixed mating system in flowering plants. Both SI and CSI are traits that increase the frequency of fertilization of ovules by outcross pollen, as opposed to self-pollen.
References
- ↑ Darwin C (2009). The Effects of Cross and Self Fertilisation in the Vegetable Kingdom. Cambridge: Cambridge University Press. doi:10.1017/cbo9780511694202.001. ISBN 978-0-511-69420-2.
- 1 2 3 4 Lloyd DG (1979). "Some Reproductive Factors Affecting the Selection of Self-Fertilization in Plants". The American Naturalist. 113 (1): 67–79. doi:10.1086/283365. S2CID 85354396.
- ↑ Busch JW, Delph LF (February 2012). "The relative importance of reproductive assurance and automatic selection as hypotheses for the evolution of self-fertilization". Annals of Botany. 109 (3): 553–62. doi:10.1093/aob/mcr219. PMC 3278291 . PMID 21937484.
- 1 2 Stebbins, GL (1957). "Extreme environments select for reproductive assurance: evidence from evening primroses (Oenothera)". The American Naturalist. 91 (861): 337–354. doi:10.1086/281999.
- ↑ Pannell JR, Auld JR, Brandvain Y, Burd M, Busch JW, Cheptou PO, ConnerJK, Goldberg EE, Grant AG, Grossenbacher DL, Hovick SM, Igic B, Kalisz S, Petanidou T, Randle AM, de Casas RR, Pauw A, Vamosi JC, Winn AA (July 2015). "The scope of Baker's law". The New Phytologist. 208 (3): 656–67. doi: 10.1111/nph.13539 . PMID 26192018.
- ↑ Kruszewski LJ, Galloway LF (2006). "Explaining Outcrossing Rate in Campanulastrum americanum (Campanulaceae): Geitonogamy and Cryptic Self‐Incompatibility". International Journal of Plant Sciences. 167 (3): 455–461. doi:10.1086/501051. ISSN 1058-5893. S2CID 85293071.
- ↑ Asande, Lydia K.; Omwoyo, Richard O.; Oduor, Richard O.; Nyaboga, Evans N. (December 2020). "A simple and fast Agrobacterium-mediated transformation system for passion fruit KPF4 (Passiflora edulis f. edulis × Passiflora edulis f. flavicarpa)". Plant Methods. 16 (1): 141. doi: 10.1186/s13007-020-00684-4 . PMC 7565748 . PMID 33088337.
- ↑ Veena V, Nampy S (2019). "Induced cleistogamy: A strategy for reproductive assurance in Murdannia nudiflora (Commelinaceae)". Botany. 97 (10): 547–557. doi:10.1139/cjb-2019-0007. ISSN 1916-2790.