Polyploidy in crop improvement and evolution

Abstract

Breeding of polyploid crops has been in progress since the domestication of crop plants, while genetic gains can be obtained through selection, evaluation and recombination, the successful selection of crop improvement may depend on understanding and unravelling the complexities of genetic variation that underlies the phenotype. The genomic sequence analysis has vastly enhanced our knowledge of plant genomes, leading to an understanding of the behaviour of polyploid plant genomes. A better understanding of polyploidy holds a great promise for crop improvement by better association between genotype and phenotype and bridging gaps for the genetic transmission of desired agronomic traits between crop species and their wild relatives. For a long period of time, polyploidy in plants has been considered to be an important phenomenon because of genome buffering, increased allelic diversity, fi xing heterozygosity and the opportunity for novel phenotypic variations because of duplicated genes which acquire new function (Stebbins, Variation and evolution in plants. Columbia University Press, Columbia, 1950). Polyploidisation followed by fractionation and duplicate gene diversifi cation provides the opportunity to reconsider the importance of polyploidy for crop improvement.