Heterostyly of flower
These morphs differ qualitatively from each other in the lengths of the pistil and filaments of the stamens . The phenotype for each morph is genetically determined.When a species has two floral morphs called distílica. In one of the morphs, called Pin, the stamens are short and the long pistils. In the other morph, called Thrum, the stamens are long and short pistils. The genus Primula are probably the best known example of heteromorphic flowers and reproductive mechanism that these species have attracted considerable attention from botanists, geneticists and evolutionists, including Charles Darwin , and in 1862. Almost all species Heterostyly exhibit self-incompatibility (AI).
The loci responsible for the AI in these species are closely linked to those genes responsible for the polymorphism floral, so that both traits are inherited together. The distyly is given a single gene with two alleles, the tristyly by two genes with two alleles each. In species that exhibit heterostyly exists a different mechanism called self-incompatibility heteromórfica AI. This mechanism is not found probably related evolutionarily to the incompatibility homomorphic systems.
In biotechnology , the somatic hybridization is the process whereby hybrid plants are obtained from the fusion of cells or protoplasts derived from somatic cells . This technique came about 30 years ago as a very promising tool to overcome problems of incompatibility precigótica .
Somatic hybridization, although it has some limitations, such as a high sterility of the resulting hybrids or inability to regenerate plants in some cases proved to be useful in breeding of crops, notably for allowing limited introgression of genes of wild in crops. Is used, for example, when attempting to transfer disease resistance or tolerance to stresses. It also allows the production of cytoplasmic hybrids (cybrids). The asymmetric hybridization cibridización serves as a bridge to the transfer of individual genes.
In botany called hydrophilicity to the adaptation of many plants flowering plants to ensure their pollination by water. We present only in very few angiosperms. In species with erect flowers, disk-shaped and concave (eg, Ranunculus ) rain water may cause self-pollination and lead to splashing grains pollen to the stigma of one flower . Adaptive mechanism is not as widespread, even among aquatic species. A major adaptation in anemophilous species is the buoyancy of pollen (eg Callitriche ) or of male flowers in other species. Thus, in Vallisneria andElodea male flowers that form near the bed where they live, emerging from the ground and rise to the surface where they float up to the female flowers of the same species. The latter, coming temporarily to the surface, where they are pollinated. In other cases ( Ceratophyllum , Najas ,Posidonia and Zostera ), pollen does not reach the water surface and is carried by water currents to reach the stigmas of female flowers. InCeratophyllum the stamens are broken by the formation of air bubbles in the aerenchyma, sometimes to break off and rise to the surface and the pollen is spherical and rich in starch granules that facilitate its sinking in the water.
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