Sex Plant - Plants males, females and hermaphrodites: Sex determination by molecular methods (PCR and RAPD)
Most plants have both sexes in each, but some have separate sexes, male specimens and other specimens female. The separation of the sexes can occur between plant specimens of some species, and also in specimens of the same species can have male flowers and female flowers. In vertebrates (mammals, birds, reptiles, fish) are sex chromosomes X and Y, but these chromosomes but have been sought in plants have been few species where it has been possible to find XY chromosomes in male specimens and chromosomes XX in female specimens. (Silene latifolia, Asparragus officinalis, Humulus lupulus, Rumex acetosa, Cannabis sativa, among others). Also, there have been known some of the genetic loci that regulate the expression of the masculine and the feminine plants.
Sexing plants, to differentiate maculinas and female, is important for cultivation, since in some cases only female are of interest. In plants the seeds usually 50% male and 50% female, so only half interested seeds and a sex would have no interest, it would be very useful to have methods to differentiate. Advances in genetic knowledge of the genes involved in sex determination of plants, offer methods to know the sex when have not yet expressed any characteristic of masculinity or femininity. Thus in the species of interest only copies can be disposed female male specimens, with such a small sample as a leaf fragment.
In developing plants can differentiate a vegetative phase and a flowering phase. In the vegetative stage the plant grows in size and height without stand apart sex, so it can not be differentiated by their macroscopic phenotypic characteristics if they are male or female. In some plants, after about 6 weeks of development, they can begin to express some phenotypic signs that guide to the type of sex before they develop male or female flowers. In the phase of flowering, the plant stops growing and devotes every effort to develop flowers leading to the sexual organs.
Male reproductive organs of flowers are the stamens (stamen) loaded with pollen (pollen-loaded stamen) and female reproductive organs are the carpels (carpels) or eggs that hold the pistil (egg-holding pistil). Insemination of plants is performed using nature as mating element: wind, such as insects, water, carrying the pollen to the stigma (stigma) adherent female. Pollen grains germinate and grow gradually and slowly down toward the eggs.
Two groups of plants, gymnosperms and angiosperms. The first of them nude and ova there with specimens with both sex, male and female organs, as occurs in 75% of all plants. Second, angiosperms, flowering plants have eggs in an ovary. In these plants, most are in the same specimen of male sexual organs and female sexual organs, while only a small number correspond to specimens with separate male and female specimens copies sexes.
In general, most plants sprout bisexual flowers, with masculine and feminine side, but sometimes develop separate male flowers and female flowers. Others have both bisexual flowers and unisexual flowers. Plants with male flowers and bisexual flowers produce more seeds. The cause of this phenomenon is unknown, but could be because the male flowers consume less energy, so it would be dedicated to produce seeds.
When you try to clssificar plants according to their sex often speak simply of male, female and hermaphrodite plants. However, terminology, if we want to be more precise, you must differentiate more complex situations, such as:
- Monomorphic plants (plants in which the same issue there are male and female sex organs) sex. These coprresponden 75% of all plants. Within this group can be found the following:
- Hermaphrodites. These plants have flowers with male and female sexual organs in the same flower. This situation is found in 90% of flowering plants (eg. The roses).
- Monoicas (monoecious): These plants have male flowers and female flowers. This situation is found in 5% of flowering plants, and in many gymnosperms (eg. Pine).
- Ginomonoicas (gynomonoecious) (male sterile). These plants have female flowers and hermaphrodite flowers (eg. Margaritas).
- Andromonicas (andromonoecious) (female sterile). These plants have male flowers and hermaphrodite flowers.
This situation should mention that cosexuales states for plants that have both sexual functions, either present in each flower (hermaphrodites), or in male and female flowers (monoecious).
- Polymorphic plants (plants where there are male and female specimens) sex. These account for 25% of all plants.
- Dioecious (dioecious). These plants have copies with separate sexes, ie there are male plants and female plants. This situation is found in 5% of flowering plants and some gymnosperms (eg Ortigas -. Nettle -).
- Ginodioicas (Ginodioecious). These plants have female specimens and hermaphrodite specimens (eg. Plantago lanceolata, and Silene vulgaris).
- Androdioica (Androdioecius). These plants have male and hermaphrodite copies copies. Occurrence is rare.
In plants sex determination depends on two loci, one of them responsible for the expression of the female organs, and others involved in activating the development of the male organ. This means that in dioecious plants (specimens with different sexes) and Silene latifolia, four whorls (whorls) of reproductive organs, showing male and female floral meristems as in any monoica espercie hermaphrodite: sepals, petals, stamens and carpels. In the initial phase meristems they are similar in male plants and female plants, ie they are undifferentiated. When the primordia of floral organs are initiated, the female organs the center of the meristem are significantly lower in male plant, the female plant. In the male plant organs develop male, while the female plant female organs develop and degenerate beginnings of male organs. The male genotype includes a suppressor gene femininity (His F).
Molecular methods for determining the sex of plants
In the absence of clearly differentiated sex chromosomes in all plants, genetic differentiation of sex had to be dealt with other strategies that can be applied to the study of any plant species with sexual polymorphism (with sexes in different specimens; dioecious in general) before to express their sex for each phenotypic characteristics.
The general strategy to know the differential genetic markers involves making a random genetic test with primers (primers), generally nucleotide decamer, by mértodo RAPD (Randomly Amplified Polymorphic DNA). Random primers with a genomic amplification of male and female adult specimens is done. This genomic amplification will lead to multiple amplicons, once separated electrophoretically on an agarose gel, may allow to differentiate patterns corresponding male and female plants. RAPD method with the SCAR markers (Sequence Characterized Amplified Region-) that identify one sex are obtained. Having identified those sequence regions SCAR can be cloned, sequenced and specific amplification procedures designed to identify the sex of the specimens.
Maculinidad markers exist for several species: Silene latifolia, Humulus luoulus, Actinidia chinensis, Cannabis sativa, among others. There are also marcadortes of femininity for several species: Pistacia vera, Actinidia sinensis, Salix viminalis, among others.
Tests conducted at the IVAMI
- Sexing by molecular methods (PCR) for male genes (male plants), as they are known male sequences MAD (Multiple-Associated DNA).
- Sexing plants sexual polymorphism (males and females) RAPD (Random Amplified Polymorphic DNA) methods for male or female genes, as they are not known.
- Small portion of leaves.
- Introduced into sterile plastic container as possible be cooled (polystyrene container -white cork- with frozen packs).
Delivery of results:
- Molecular methods: 48 to 72 hours.
Cost of the test:
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