多胚形成、多胚現象

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/03/02 03:34:51」(JST)

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Polyembryony is the phenomenon of two or more embryos developing from a single fertilized egg (in humans, identical twins). Polyembryony occurs regularly in many plants and animals. The nine banded armadillo, for instance, usually gives birth to four identical young. Polyembryony is best known among parasitoid insects of the order Hymenoptera, families Encyrtidae, Dryinidae, Platygasteridae and Braconidae. The term is also used in botany to describe the phenomenon of two seedlings emerging from one seed.

In plants, polyembryony often gives rise to the enigma of a single offspring.^[1] The mechanism underlying this phenonomenon is programmed cell death (PCD) which removes all but one embryo.

A more striking example of the use of polyembryony as a competitive reproductive tool is found in the parasitoid Hymenoptera family Encyrtidae. The progeny of the splitting embryo develop into at least two forms, those that will develop into adults and those that become a type of soldier, called precocious larvae. These latter larvae patrol the host and kill any other parasitoids they find with the exception of their siblings, usually sisters.^[2]

Polyembryony also occurs in Bryozoa.

References

^ Filonova LH, von Arnold S, Daniel G and Bozhkov PV (October 2002). "Programmed cell death eliminates all but one embryo in a polyembryonic plant seed". Nature 9 (10): 1057–1062. doi:10.1038/sj.cdd.4401068.
^ N.E. Beckage; S.N. Thompson; B.A. Federici (1990). Parasites and Pathogens of Insects", Vol. 1: Parasites, Vol. 2: Pathogens. Academic Press. San Diego. pp. 2 Volumes. ISBN 0-412-07401-X. Retrieved 22 January 2011.

External links

Juan Manuel Alvarez A. (15 April 1997). "Chapter 26 — Largest Parasitoid Brood". Book of Insect Records. University of Florida.
J. Bronté Gatenby (1918). "Memoirs: Polyembryony in Parasitic Hymenoptera: A Review journal=Quarterly Journal of Microscopical Science". s2-63. pp. 175–196.
J. Bronté Gatenby (1918). "The Segregation of the Germ-cells in Trichogramma evanescens". Quarterly Journal of Microscopical Science. s2-63: 161–174.

1997 Craig, S.F., L.B. Slobodkin, and G. Wray. The 'Paradox' of Polyembryony: A review of the cases and a hypothesis for its evolution. Evolutionary Ecology, 11 (2): 127-143.

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English Journal

Microsatellite and flow cytometry analysis to help understand the origin of Dioscorea alata polyploids.

Nemorin A1, David J, Maledon E, Nudol E, Dalon J, Arnau G.Author information 1CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement), Station de Roujol, 97170 Petit Bourg, Guadeloupe, France.AbstractBACKGROUND AND AIMS: Dioscorea alata is a polyploid species with a ploidy level ranging from diploid (2n = 2x = 40) to tetraploid (2n = 4x = 80). Ploidy increase is correlated with better agronomic performance. The lack of knowledge about the origin of D. alata spontaneous polyploids (triploids and tetraploids) limits the efficiency of polyploid breeding. The objective of the present study was to use flow cytometry and microsatellite markers to understand the origin of D. alata polyploids.
Annals of botany.Ann Bot.2013 Sep;112(5):811-9. doi: 10.1093/aob/mct145. Epub 2013 Aug 1.
BACKGROUND AND AIMS: Dioscorea alata is a polyploid species with a ploidy level ranging from diploid (2n = 2x = 40) to tetraploid (2n = 4x = 80). Ploidy increase is correlated with better agronomic performance. The lack of knowledge about the origin of D. alata spontaneous polyploids (triploids and
PMID 23912697

Mating in the pseudogamic apomictic Anemopaegma acutifolium DC: another case of pseudo-self-compatibility in Bignoniaceae?

Sampaio DS1, Bittencourt NS Jr, Oliveira PE.Author information 1Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil.AbstractSelf-compatibility in apomictic pseudogamic species is considered fundamental to assure reproduction by seeds in extreme situations, making apomictic species more advantageous than sexual ones in these scenarios. Anemopaegma acutifolium is a polyploidy, apomictic sporophytic species with no endosperm development in ovules of unpollinated pistils, which indicates obligate pseudogamy. Thus, the aim of the present work is to study the breeding system and post-pollination events to test if there is similar pseudogamous development irrespective of pollination treatment. We analysed fruit and seed set obtained in controlled experimental pollinations, as well as embryo number per seed, and the progress of ovule penetration, fertilisation and early endosperm development between self- and cross-pollinated pistils. We found that the species is self-fertile and that spontaneous selfing fruit set is also possible, although emasculated flowers never form fruits. Selfed pistils were as efficient as crossed ones for all parameters analysed, except for a delay in endosperm development observed in the former that may be an effect of the late-acting self-incompatibility. Therefore, the avoidance of selfed pistil abortion seems to be promoted by the presence of adventitious embryos and a normal endosperm. We conclude that A. acutifolium shows apomixis-related pseudo-self-compatibility, as in other self-fertile apomictic species of Bignoniaceae, which confer reproductive assurance and increases fruit-set and persistence ability in fast-changing tropical habitats.
Plant biology (Stuttgart, Germany).Plant Biol (Stuttg).2013 Sep;15(5):919-24. doi: 10.1111/j.1438-8677.2012.00692.x. Epub 2012 Nov 5.
Self-compatibility in apomictic pseudogamic species is considered fundamental to assure reproduction by seeds in extreme situations, making apomictic species more advantageous than sexual ones in these scenarios. Anemopaegma acutifolium is a polyploidy, apomictic sporophytic species with no endosper
PMID 23126331

Micropropagation of Citrus spp. by organogenesis and somatic embryogenesis.

Chiancone B1, Germanà MA.Author information 1Dipartimento DEMETRA, Facoltà di Agraria, Università degli Studi di Palermo, Palermo, Italy.AbstractCitrus spp., the largest fruit crops produced worldwide, are usually asexually propagated by cuttings or grafting onto seedling rootstocks. Most of Citrus genotypes are characterized by polyembryony due to the occurrence of adventive nucellar embryos, which lead to the production of true-to-type plants by seed germination. Tissue culture and micropropagation, in particular, are valuable alternatives to traditional propagation to obtain a high number of uniform and healthy plants in a short time and in a small space. Moreover, in vitro propagation provides a rapid system to multiply the progeny obtained by breeding programs, allows the use of monoembryonic and seedless genotypes as rootstocks, and it is very useful also for breeding and germplasm preservation.In this chapter, two protocols regarding organogenesis of a rootstock and somatic embryogenesis of a cultivar have been described.
Methods in molecular biology (Clifton, N.J.).Methods Mol Biol.2013;11013:99-118. doi: 10.1007/978-1-62703-074-8_8.
Citrus spp., the largest fruit crops produced worldwide, are usually asexually propagated by cuttings or grafting onto seedling rootstocks. Most of Citrus genotypes are characterized by polyembryony due to the occurrence of adventive nucellar embryos, which lead to the production of true-to-type pla
PMID 23179693

Japanese Journal

我が国におけるカンキツの品種育成

長谷川美典
日本食品科学工学会誌 : Nippon shokuhin kagaku kogaku kaishi = Journal of the Japanese Society for Food Science and Technology 60(10), 609-613, 2013-10-15
NAID 10031202134

香酸カンキツ雑種実生群における不稔葯の形態と細胞質–核雄性不稔の遺伝

Dewi Prita Sari,若菜章,谷本祐 [他],藤原由美子,酒井かおり,梶原康平
Journal of the Japanese Society for Horticultural Science 82(3), 203-214, 2013
香酸カンキツ類における無核品種育成のための重要な形質である雄性不稔性の遺伝については，これらが多胚性であり，幼若期間も長いことから，ほとんど分かっていない．そこで，16 種類の雄性稔性の香酸カンキツを用いた 22 組合せの交配を行って雑種実生を獲得し，ウンシュウミカン成木に高接ぎして開花させた．さらに，単胚性で雄性不稔である HY16 と'清見'を種子親にして 4 交配を行って雑種実生を作出し，幼 …
NAID 130004510783

我が国におけるカンキツの品種育成

長谷川美典
日本食品科学工学会誌 60(10), 609-613, 2013
… Polyembryony is a fatal obstacle specific to citrus cross-breeding in many cultivars in which a high percentage of seedlings are not hybrids, but rather identical to the female parent, which severely hinders cross-breeding. …
NAID 130003384264