Apomixis Optional In Flowers

Most apomictic species are optional, so that seed can produce both asexual and sexually in a balanced system. The apomictic required prevailing particularly in those species that are sexually sterile, for example where only one sex is present ( Elodea canadensis , Petasites hybridus ), where only one genotype alleles of self-incompatibility ( Menyanthes trifoliata , Hottonia palustris ) , or where sexuality can not function normally due to disturbances in meiosis caused by interspecific hybridization ( Mentha , Mimulus ) or imparipoliploida ( Potentilla anserina , Holcus mollis ).
Apomixis is widespread in certain plant families such as Poaceae , the Rosaceae and composed . Apomixis in the latter type of reproduction is a must in many species, while in the other two families facultative apomixis is common
In botany , it is called cleistogamy breeding mechanism by which the flower self-pollinated and selfed because it is closed. Because the flower opens cleistogamy is a form of autogamy must.
The species that exhibit this mechanism of reproduction are said cleistogamous . The cleistogamy can be optional or required. In the first case, the plant has cleistogamous flowers and flowerschasmgamas , ie presenting cross-pollination and therefore are capable of being fertilized by other plants. Cleistogamous species required, however, only cleistogamous flowers present and, therefore, are strictly self-pollinating, all the seed comes from the selfing of the mother plant. In many species descriptions use the terms "predominantly cleistogamous" to indicate that the most common type of reproduction is cleistogamy.
In the family of the grasses of cleistogamy is quite common. It has been reported in 19 of the 60 tribes in which the family is divided. In fact, 70 genera of grasses have cleistogamous species.
The flowers of cleistogamous species, in general, are small, unnoticed, have pedicels short and often are associated with flowering ground ( Arachis , Paspalum amphicarpum ). It is also often presentanthers smaller or fewer anthers chasmgamas related species. In the genus Briza , for example, species pollinated and self-incompatible present three anthers while the two species exhibit only cleistogamous anther and it has only one tenth the size.
The cultivation of the mixture is a technique based on placing a piece of plant in a container helped with nutrient solutions and artificial hormones vegetable or able to propagate in a sterile environment, ie in an environment free of microorganisms (clean). Each plant produces a fragment identical to the fragment was taken, but may be genetically modified to have artificial varieties.
In recent decades have developed different systems for the cultivation of protoplasts, cells, tissues and plant organs, one of them is growing in suspension (cell suspensions), which is a way to maintain and propagate plant cells.
Cell suspensions consist of free cells and cell aggregates distributed in a moving medium. These suspensions may be permanent by continuous supply of nutrients. Culture media for the cultivation of cell suspensions of a variety of plants has been used MS medium developed by Murashige and Skoog (1962) for tissue culture snuff, as well as B-5 medium of Gamborg et al. (1968). Were also used other means, but its composition does not differ much from those given above. Often, the best means of induction and callus growth from primary explants are not the same as for establishment of cell suspensions, the optimal level of auxin and cytokinin, eg may be different ( Torrey et al. , 1961). Sometimes suspension cells need organic supplements, amino acids, CH, yeast extract, and AC, the most widely used auxin is 2,4-D. Initiation of cell suspensions Suspensions are generally initiated by incubation of pieces of friable calluses in liquid media that are in continuous motion. Erlenmeyer flasks are commonly used, in which liquid is deposited with the pieces scattered on the callus to fill about 1 / 5 of the ability to cough bottles and these are then placed to incubate on a rotary shaker at 80-150 rpm under continuous light at 25 C temperature. Through weekly subcultures, the cell suspensions are established after several days. During the first subcultures is recommended to use a low dilution rate using four parts of fresh medium to one part cell suspension. You can then use a higher dilution rate, according to the purpose for which the suspension has been established.



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