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Heterosis or hybrid vigor, on the other hand, is the tendency of outbred strains to exceed both inbred parents in fitness. Selective breeding of plants and animals, including hybridization, began long before there was an understanding of underlying scientific principles.
Heterosis describes the tendency of the progeny of a specific cross to outperform both parents. The detection of the usefulness of heterosis for plant breeding has led to the development of inbred lines that reveal a heterotic yield advantage when they are crossed. Maize was the first species where heterosis was widely used to produce hybrids.
The detection of the usefulness of heterosis for plant breeding has led to the development of inbred lines that reveal a heterotic yield advantage when they are crossed. Maize was the first species where heterosis was widely used to produce hybrids.
Classical genetics is often referred to as the oldest form of genetics, and began with Gregor Mendel's experiments that formulated and defined a fundamental biological concept known as Mendelian inheritance. Mendelian inheritance is the process in which genes and traits are passed from a set of parents to their offspring.
Gregor Mendel focused on patterns of inheritance and the genetic basis for variation. In his cross-pollination experiments involving two true-breeding, or homozygous , parents, Mendel found that the resulting F1 generation was heterozygous and consistent.
Heterosis is the tendency for hybrid individuals to exceed their purebred parents in size and vigor. The phenomenon has long been known in animals and plants. Heterosis appears to be largely due to genetic complementation, that is the masking of deleterious recessive alleles in hybrid individuals.
The parent strains used are carefully chosen so as to achieve the uniformity that comes from the uniformity of the parents, and the superior performance that comes from heterosis. [ 3 ] Elite inbred strains are used that express well-documented and consistent phenotypes with yield that is relatively good for inbred plants. [ 2 ]
The masking effect of outcrossing is known as genetic complementation, [3] an effect also recognized as hybrid vigor or heterosis. Once outcrossing is established in a lineage of flowering plants due to the benefit of genetic complementation, subsequent switching to inbreeding becomes disadvantageous because it allows expression of the ...