double fertilization The production of 2 sperm nuclei, both of which contribute to fertilization. The male gametophyte, comprising the pollen grain and pollen tube, contains 2 sperm nuclei and 1 vegetative nucleus. The vegetative nucleus degenerates once the pollen tube has penetrated the embryo sac. The 2 sperm nuclei enter the embryo sac. One unites with the egg nucleus to form the zygote, which develops into the embryo. The other unites with both of the polar nuclei or with the secondary (definitive) nucleus formed by their fusion, to form the primary endosperm nucleus, from which the endosperm develops. Double fertilization occurs only in angiosperms, with the single exception of the gymnosperm genus Ephedra, in which 2 sperm nuclei are produced, 1 of which fuses with the egg nucleus. The other unites with an adjacent cell, but develops no further.
double fertilization A process, unique to flowering plants, in which two male gamete nuclei, which have travelled down the pollen tube, separately fuse with different female nuclei in the embryo sac. The first male nucleus fuses with the egg cell to form the zygote; the second male nucleus fuses with the two polar nuclei to form a triploid nucleus that develops into the endosperm.
double fertilization In flowering plants, the union of one sperm nucleus with the egg nucleus and of a second sperm nucleus with the two polar nuclei to form a triploid endosperm nucleus. The male gametophyte (the pollen grain and pollen tube) contains three sperm nuclei, but one (the vegetative nucleus) degenerates once double fertilization has been accomplished.
More From encyclopedia.com
Double , Double The etheric counterpart of the physical body which, when out of coincidence, may temporarily move about in space in comparative freedom and ap… Embryo Sac , embryo sac The female gametophyte (an oval structure in the nucellus of the ovule) of flowering plants, formed by the division of the haploid megaspo… Double Entendre , double entendre •airer, bearer, carer, Clara, darer, declarer, Demerara, Éire, habanera, Halmahera, parer, Perak, primavera, repairer, Rivera, Rivier… Contrabassoon , double bassoon (contrabassoon; Fr. ‘contrebasson’; Ger. ‘Kontrafagott’). Wind instr. octave deeper than bassoon and notated octave higher than it sou… polyembryony , polyembryony 1. The formation of more than one embryo in a plant seed. Often one embryo develops from the fertilized egg cell, while the others have… Egg Membrane , egg membrane The layer of material that covers an animal egg cell. Primary membranes develop in the ovary and cover the egg surface in addition to th…
About this article
All Sources -
Updated About encyclopedia.com content Print Topic
You Might Also Like