Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: January 3, 2009
Publication Date: December 20, 2009
Citation: Peloquin, S.J., Simon, P.W., Jansky, S.H. 2009. The Concept of Horizontal Linkage and Its Application to Genetics and Breeding. In: Mohan, R.H., editor. Research Advances in Heredity. 1st edition. Kerala, India:Global Research Network. p. 1-7.
In diploid organisms, all dominance and many epistatic interactions are lost during the formation of gametes by meiosis. While outcrossing strategies may help to restore heterozygosity upon fertilization, there are few examples of mechanisms that retain inter- and intra-locus interactions during sexual reproduction. Numerically unreduced (2n) gametes formed by first division restitution (FDR) mechanisms provide a means to transmit non-additive genetic variance to offspring. In each chromosomal region from the centromere to the first crossover, all loci are transmitted intact to progeny. Consequently, all dominance and epistatic interactions of the parent conferred by these regions are found in the offspring. We propose the use of the term “horizontal linkage” to describe the intact transmission of these blocks of genes, across all chromosomes, to offspring via FDR 2n gametes. Horizontal linkage provides a powerful mechanism to exploit non-additive genetic variation for plant improvement. In potato, most genes associated with yield are located between the centromere and the first crossover. FDR 2n gametes have been shown to effectively transmit dominant and epistatic interactions to offspring, producing uniform, high-yielding families. Horizontal linkage is likely to play an important role in the evolution of polyploid species as well as the improvement of polysomic polyploid crops.