Pseudogamy
Encyclopedia
Pseudogamy refers to aspects of reproduction. It has come to have different (but related) meanings in zoology
and in botany
.
in which the sperm stimulates the egg cell to develop into an embryo
, but no male inheritance is transmitted. Gynogenesis is a synonym.
. Focke
(1881) is usually cited for the definition of the term. What he actually said was (page 525, translated)
Thus in botany, "pseudogamy" is used for any reproductive process that requires pollination
but does not involve male inheritance. It is sometimes used in a restrictive sense to refer to types of agamospermy in which the endosperm
is fertilized but the embryo is not (see Pseudogamous apomixis, below). A better term for the restrictive sense is centrogamy.
in flowering plants (angiosperms) includes some types of vegetative reproduction and also agamospermy which is asexual reproduction through seeds (see apomixis
for more information). Agamospermy can occur through many different mechanisms, some of which require pollination (pseudogamy), and some which do not (autonomous apomixis). Many flowering plants with pseudogamous apomixis require fertilization to produce the endosperm
of the seed
. However, it was recently shown that pollination with compatible pollen can be required even in some species where endosperm development is autonomous.
Pseudogamous apomixis occurs in many families
. It is particularly common in Rosaceae
and Poaceae
, where it occurs in many different genera
and species
. Examples of species with pseudogamous apomixis include the Himalayan blackberry Rubus armeniacus
and gamagrass Tripsacum dactyloides
.
Autonomous apomixis is the rule among the many apomictic species of Asteraceae
, and also occurs in several genera of Poaceae
. Species with autonomous apomixis include the common dandelion Taraxacum officinale
.
Zoology
Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...
and in botany
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
.
In zoology
In zoology it is used for a type of parthenogenesisParthenogenesis
Parthenogenesis is a form of asexual reproduction found in females, where growth and development of embryos occur without fertilization by a male...
in which the sperm stimulates the egg cell to develop into an embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
, but no male inheritance is transmitted. Gynogenesis is a synonym.
In botany
In botany, "pseudogamy" is also related to asexual reproductionAsexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
. Focke
Wilhelm Olbers Focke
Wilhelm Olbers Focke was a medical doctor and botanist who in 1881 published a significant work on plant breeding entitled Die Pflanzen-Mischlinge, Ein Beitrag zur Biologie der Gewächse which briefly mentioned Gregor Mendel's discoveries on hybridization...
(1881) is usually cited for the definition of the term. What he actually said was (page 525, translated)
- "III PSEUDOGAMY.
In experiments to raise hybrids, you sometimes get plants which resemble the mother plant, but partly in their sexual potency appear noticeably weakened. They have for this reason often been taken for hybrids. I suspect that in such cases the foreign pollen no real fertilization completed, but only gave the stimulus to produce the outer parts of fruit. The seeds, which are found in the fruit, are, in my opinion, not spawned by hybridization and generally not through sexual procreation, rather they are incurred parthenogeneticallyParthenogenesisParthenogenesis is a form of asexual reproduction found in females, where growth and development of embryos occur without fertilization by a male...
."
Thus in botany, "pseudogamy" is used for any reproductive process that requires pollination
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
but does not involve male inheritance. It is sometimes used in a restrictive sense to refer to types of agamospermy in which the endosperm
Endosperm
Endosperm is the tissue produced inside the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This makes endosperm an important source of nutrition in human diet...
is fertilized but the embryo is not (see Pseudogamous apomixis, below). A better term for the restrictive sense is centrogamy.
Pseudogamous apomixis
ApomixisApomixis
In botany, apomixis was defined by Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization. This definition notably does not mention meiosis...
in flowering plants (angiosperms) includes some types of vegetative reproduction and also agamospermy which is asexual reproduction through seeds (see apomixis
Apomixis
In botany, apomixis was defined by Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization. This definition notably does not mention meiosis...
for more information). Agamospermy can occur through many different mechanisms, some of which require pollination (pseudogamy), and some which do not (autonomous apomixis). Many flowering plants with pseudogamous apomixis require fertilization to produce the endosperm
Endosperm
Endosperm is the tissue produced inside the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This makes endosperm an important source of nutrition in human diet...
of the seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
. However, it was recently shown that pollination with compatible pollen can be required even in some species where endosperm development is autonomous.
Pseudogamous apomixis occurs in many families
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
. It is particularly common in Rosaceae
Rosaceae
Rosaceae are a medium-sized family of flowering plants, including about 2830 species in 95 genera. The name is derived from the type genus Rosa. Among the largest genera are Alchemilla , Sorbus , Crataegus , Cotoneaster , and Rubus...
and Poaceae
Poaceae
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...
, where it occurs in many different genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
and species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. Examples of species with pseudogamous apomixis include the Himalayan blackberry Rubus armeniacus
Rubus armeniacus
Rubus armeniacus, Armenian Blackberry or Himalayan Blackberry, is a species of Rubus in the blackberry group Rubus subgenus Rubus series Discolores Focke. It is native to Armenia in southwest Asia, and widely naturalised elsewhere...
and gamagrass Tripsacum dactyloides
Tripsacum dactyloides
Tripsacum dactyloides is a prairie grass of the Great Plains. Gama Grass is found as far northwest as Nebraska....
.
Autonomous apomixis is the rule among the many apomictic species of Asteraceae
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
, and also occurs in several genera of Poaceae
Poaceae
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...
. Species with autonomous apomixis include the common dandelion Taraxacum officinale
Taraxacum officinale
Taraxacum officinale, the common dandelion , is a herbaceous perennial plant of the family Asteraceae . It can be found growing in temperate regions of the world, in lawns, on roadsides, on disturbed banks and shores of water ways, and other areas with moist soils. T...
.