Inherited allelic variants and novel karyotype changes influence fertility and genome stability in Brassica allohexaploids

• DOI: 10.1111/nph.15804
• Publication Date: 2019-03-20T00:03:08Z
• Authors: Roman Gaebelein; Sarah V. Schiessl; Birgit Samans; Jacqueline Batley; Annaliese S. Mason
• Keywords: 0301 basic medicine; 572; Karyotype; Gene Dosage; Inheritance Patterns; Brassica; Subgenome fractionation; Chromosomes, Plant; Genomic Instability; Translocation, Genetic; Polyploidy; Cytogenetics; 03 medical and health sciences; Chromosome Segregation; Gene Duplication; Meiosisgenes; Alleles; Crosses, Genetic; 580; Gene Rearrangement; Genetic Variation; Allopolyploids; Genome evolution; Meiosis; Fertility; Seeds; Chromosome Deletion; Genome, Plant

Synthetic allohexaploid Brassica hybrids (2n = AABBCC) do not exist naturally, but can be synthesized by crosses between diploid and/or allotetraploid species. Using these hybrids, we aimed to identify how novel allohexaploids restore fertility and normal meiosis after formation. Chromosome inheritance, genome structure, meiotic behaviour were assessed in three segregating populations derived from the cross (B. napus × B. carinata) juncea using a combination of molecular marker genotyping, phenotyping cytogenetics. Plants with unbalanced A-C translocations one direction (where C-genome chromosome fragment replaces an A-genome fragment) other showed significantly reduced across all populations. Genomic regions associated contained several genes putatively causal mutations inherited parents (copies SCC2 A genome, PAIR1/PRD3, PRD1 ATK1/KATA/KIN14a B MSH2 SMC1/TITAN8 C genome). Reduced seed loss fragments only subgenome following homoeologous exchanges could comprise mechanism for biased fractionation allopolyploids. Pre-existing gene variants present may help stabilize allohexaploids.