Pentaploidization Enriches the Genetic Diversity of Wheat by Enhancing the Recombination of AB Genomes

Fan Yang; Hongshen Wan; Jun Li; Qin Wang; Ning Yang; Xinguo Zhu; Zehou Liu; Yumin Yang; Wujun Ma; Xing Fan; Wuyun Yang; Yonghong Zhou

doi:10.3389/fpls.2022.883868

Pentaploidization Enriches the Genetic Diversity of Wheat by Enhancing the Recombination of AB Genomes

Front Plant Sci. 2022 Jun 29:13:883868. doi: 10.3389/fpls.2022.883868. eCollection 2022.

Authors

Fan Yang^{1

2}, Hongshen Wan², Jun Li², Qin Wang², Ning Yang², Xinguo Zhu², Zehou Liu², Yumin Yang³, Wujun Ma⁴, Xing Fan¹, Wuyun Yang², Yonghong Zhou¹

Affiliations

¹ Triticeae Research Institute, Sichuan Agricultural University, Chengdu, China.
² Key Laboratory of Wheat Biology and Genetic Improvement in Southwestern China (Ministry of Agriculture and Rural Affairs of P.R.C.), Crop Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, China.
³ Institute of Agricultural Resources and Environment, Sichuan Academy of Agricultural Sciences, Chengdu, China.
⁴ Australia-China Joint Centre for Wheat Improvement, College of Science, Health, Engineering and Education, Murdoch University, Perth, WA, Australia.

Abstract

Allohexaploidization and continuous introgression play a key role in the origin and evolution of bread wheat. The genetic bottleneck of bread wheat resulting from limited germplasms involved in the origin and modern breeding may be compensated by gene flow from tetraploid wheat through introgressive hybridization. The inter-ploidy hybridization between hexaploid and tetraploid wheat generates pentaploid hybrids first, which absorbed genetic variations both from hexaploid and tetraploid wheat and have great potential for re-evolution and improvement in bread wheat. Therefore, understanding the effects of the pentaploid hybrid is of apparent significance in our understanding of the historic introgression and in informing breeding. In the current study, two sets of F₂ populations of synthetic pentaploid wheat (SPW1 and SPW2) and synthetic hexaploid wheat (SHW1 and SHW2) were created to analyze differences in recombination frequency (RF) of AB genomes and distorted segregation of polymorphic SNP markers through SNP genotyping. Results suggested that (1) the recombination of AB genomes in the SPW populations was about 3- to 4-fold higher than that in the SHW populations, resulting from the significantly (P < 0.01) increased RF between adjacent and linked SNP loci, especially the variations that occurred in a pericentromeric region which would further enrich genetic diversity; (2) the crosses of hexaploid × tetraploid wheat could be an efficient way to produce pentaploid derivatives than the crosses of tetraploid × hexaploid wheat according to the higher germination rate found in the former crosses; (3) the high proportion of distorted segregation loci that skewed in favor of the female parent genotype/allele in the SPW populations might associate with the fitness and survival of the offspring. Based on the presented data, we propose that pentaploid hybrids should increasingly be used in wheat breeding. In addition, the contribution of gene flow from tetraploid wheat to bread wheat mediated by pentaploid introgressive hybridization also was discussed in the re-evolution of bread wheat.

Keywords: adaptive evolution; chromosome recombination; genetic bottleneck; linkage drag; pentaploid.