Polyploidization enhancing genetic recombination of the ancestral diploid genome in the evolution of hexaploid wheat

Abstract

Allopolyploidy increases its evolutionary potential by fixing heterosis and the 1 advantage of gene redundancy. Allelic combinations generated from genetic recombination 2 potentially provide many variations to the selection pools for evolution. May there be any 3 relationship between allopolyploidization and genetic recombination? To study the impact of 4 polyploidy on genetic recombination, we selected wheat as a model and simulated its evolution 5 pathway of allopolyploidy by developing synthetic hexaploid wheat. The change of homologous 6 chromosome recombination were investigated on their diploid DD and tetraploid AABB genomes 7 after their allohexaploidization, respectively. The genetic recombination of the ancestral diploid 8 genome of Aegilops tauschii was enhanced significantly more than 2 folds after their 9 hexaploidization. Hexaploidization enhancing genetic recombination of the ancestral diploid D 10 genome was firstly reported to be a new way to increase evolutionary potential of wheat, which is 11 beneficial for wheat to conquer their narrow origination of D genome, quickly spread and make it 12 a major crop of the world. Finally, re-synthetizing hexaploid wheat using diverse Ae. tauschii 13 species with tetraploid wheat can be considered as a pleiotropic strategy to speed adaptive 14 evolution of bread wheat in breeding processes by increasing both gene allele types and genetic 15 recombination variations. 16