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Inherited allelic variants and novel karyotype changes influence fertility and genome stability in Brassica allohexaploids
Author(s) -
Gaebelein Roman,
Schiessl Sarah V.,
Samans Birgit,
Batley Jacqueline,
Mason Annaliese S.
Publication year - 2019
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15804
Subject(s) - biology , genetics , genome , meiosis , ploidy , nondisjunction , chromosome , gene , aneuploidy
Summary Synthetic allohexaploid Brassica hybrids (2 n = AABBCC ) do not exist naturally, but can be synthesized by crosses between diploid and/or allotetraploid Brassica species. Using these hybrids, we aimed to identify how novel allohexaploids restore fertility and normal meiosis after formation. Chromosome inheritance, genome structure, fertility and meiotic behaviour were assessed in three segregating allohexaploid populations derived from the cross ( B. napus × B. carinata ) × B. juncea using a combination of molecular marker genotyping, phenotyping and cytogenetics. Plants with unbalanced A–C translocations in one direction (where a C‐genome chromosome fragment replaces an A‐genome fragment) but not the other (where an A‐genome fragment replaces a C‐genome fragment) showed significantly reduced fertility across all populations. Genomic regions associated with fertility contained several meiosis genes with putatively causal mutations inherited from the parents (copies of SCC 2 in the A genome, PAIR 1/ PRD 3 , PRD 1 and ATK 1/ KATA / KIN 14a in the B genome, and MSH 2 and SMC 1/ TITAN 8 in the C genome). Reduced seed fertility associated with the loss of chromosome fragments from only one subgenome following homoeologous exchanges could comprise a mechanism for biased genome fractionation in allopolyploids. Pre‐existing meiosis gene variants present in allotetraploid parents may help to stabilize meiosis in novel allohexaploids.