Major chromosome rearrangements in intergeneric wheat x rye hybrids in compatible and incompatible crosses detected by GBS read coverage analysis
The presence of incompatible alleles in primary amphidiploids is the main trigger for starting investigating the chromosome rearrangement process in newly formed wheat-rye hybrids. In incompatible crosses resulting in fertile amphidiploids, the elimination of one of the incompatible alleles Eml-A1 or Eml-R1b can occur already in the somatic tissue of the wheat x rye hybrid embryo. We observed that the interaction of incompatible loci Eml-A1 of wheat and Eml-R1b of rye after overcoming embryo lethality leads to hybrid sterility in primary triticale. During subsequent seed reproductions (R1, R2 or R3) most of the chromosomes of A, B, D and R subgenomes undergo rearrangement or eliminations that through natural selection increase the fertility of the amphidiploid. GBS coverage analysis showed that improved fertility is associated with the elimination of entire and partial chromosomes carrying factors that either cause the disruption of plant development in hybrid plants or lead to the restoration of the euploid number of chromosomes (2n=56) in the absence of one of the incompatible alleles. Highly fertile offspring obtained in compatible and incompatible crosses can be successfully adapted for production of the triticale prebreeding stocks.