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Polygenic inheritance, in its most basic form, refers to a character or phenotypic trait that is controlled by multiple genes. It is a type of quantitative inheritance in biology in which two or more independent genes have an additive effect on a single phenotypic trait. Polygenic inheritance is defined as quantitative inheritance in which multiple free genes have a similar or additive effect on a single quantitative attribute. A polygenic locus is any individual locus that is part of the system of genes responsible for the genetic component of variation in a quantitative (polygenic) character.
Polygenic Inheritance:
Polygenic inheritance differs from Mendelian inheritance in terms of pattern and expression. In Mendelian Inheritance, each phenotypic trait is monogenic, which means that its expression is either expressed or masked depending on whether it is a dominant’ or recessive’ gene. In polygenic inheritance, where the phenotypic expression of a trait in an offspring is a mixture or additive of traits displayed in parents, the phenotypic expression of a trait in an offspring does not display complete dominance. In polygenic inheritance, the traits present in the parents are additive. This type of inheritance pattern is known as the polygenic inheritance pattern.
Polygenes are genes that, when combined with other genes, have a minor effect on phenotypes. A single gene’s impact is often insignificant and goes unnoticed. A large number of genes produce the same result. Each allele contributes to the outcome in a cumulative or additive manner. Because the expression of one gene is not masked by the presence of the other genes, epistasis is not involved. In polygenic inheritance, there are no dominant or masked genes; they are either contributing (active allele) or non-contributing (null allele). The phenotype of a trait is constantly changing in polygenic inheritance. Because the polygenic inheritance pattern is so complex, it is difficult to predict.
Examples of Polygenic Inheritance in Plants:
Polygenic inheritance patterns can be statistically analysed to aid in the estimation of population parameters.
- The kernal colour of wheat
The colour of the wheat kernel is determined by the expression of three independently assorted pairs of alleles. The dominant allele, AABBCC, is found in dark red wheat kernels, while the recessive allele, aabbcc, is found in white kernels. As a result, when AABBCC wheat is crossed with aabbcc, the F1 generation has a red colour kernel intermediate to AaBbCc. Furthermore, one white kernel plant would be produced during crossbreeding in the F2 generation, while 63 red kernel plants of various shades would be produced.
- The length of the corolla in tobacco
Five genes determine the length of the tobacco plant’s corolla. Tobacco corolla length variation is caused by polygenic inheritance.
Polygenic Inheritance
Polygenic inheritance is defined as quantitative inheritance in which multiple free genes have a similar or additive effect on a single quantitative attribute. A polygenic locus is any individual locus that is part of the system of genes responsible for the genetic component of variation in a quantitative (polygenic) character. Allelic substitutions contribute to the variation of a quantitative character. A polygenic locus can be a single gene or a complex genetic locus, i.e., a single gene or a group of functionally related genes. Polygenic inheritance occurs when two or more genes control the same trait. Genes are frequently numerous but have little effect. In humans, polygenic inheritance can be seen in height, skin colour, eye colour, and weight. Polygenes can be found in other organisms as well. Drosophila polygeny can be seen in traits such as wing morphology, bristle count, and many others.
The modern term for the mode of inheritance of polygenic patterns is polygenic inheritance. A polygene is a non-epistatic gene that interacts additively with other genes to influence phenotypic trait, contributing to multiple-gene inheritance (polygenic inheritance, multigenic inheritance, quantitative inheritance[1]), a type of non-Mendelian inheritance, as opposed to single-gene inheritance, which is the core concept of Mendelian inheritance. Because it is frequently difficult to distinguish the effect of a single gene from the effects of other genes and the environment on a specific phenotype, the term “monozygous” is frequently used to refer to a hypothetical gene.
Conclusion:
Polygenic inheritance is also known as multiple sequence inheritance or multiple issue inheritance. Polygenes have evolutionary significance and play a role in population variation. Polygenic variations or changes drive species evolution (polygenesis). This is also known as the polygeny theory in the context of evolution. The differences are determined by the individual’s or species’ specific requirements and needs. These are in charge of the majority of the adaptive changes. Polygenes are most commonly used by plant breeders. Genetic variability is stored in polygenic complexes. Following interbreeding, segregation and recombination of polygenic genes results in the release of a species’ hidden variability.
