Genetic Variation and Stability Analysis of an Artificially Synthesized Allohexaploid Brassica for Breeding Innovations

Allopolyploids play an essential role in plant evolution and confer apparent advantages on crop growth and breeding compared to low ploidy levels. A doubled haploid (DH) population derived from the cross between two artificially synthesized allohexaploid Brassica was created and self-crossed continuously. Morphological and yield-related traits showed considerable variation among different generations, different families and even within the same families. However, the flowering time, pollen viability and seed yield increased gradually during the selfing process. Ploidy level estimation and karyotyping analysis revealed that this population was chimeras with varied chromosome numbers within an identical plant. Chromosome translocations analysis showed that the B genome was more instable compared to the A and C genomes. The A genome was more prone to chromosome recombination than the C genome. Although some genomic regions were more likely to be duplicated, deleted, or rearranged, a consensus pattern was not shared between different progenies. This research deepened our understanding of the genetic variation of artificially synthesized allohexaploid Brassica. In addition, the allohexaploid Brassica can be used as a bridge to transfer some of the valuable traits blocked by reproductive barriers from wild Brassica species to cultivated species such as cold and drought resistance, etc.