rDNA ITS and cpDNA Highlight the Complexity of Genome Re-Diploidization in Lolium and Festuca Hybrids

The parental genomes of Lolium multiflorum and Festuca arundinacea were found to be unstable (3% frequency) when composed together in the hybrid L. multiflorum x F. arundinacea (2n=8x=56) which leads to a cascade of genomic rearrangements and presents us with examples of instant genome segregation at the somatic level. GISH has demonstrated that the segregated diploids (‘novel diploids’) arise through re-diploidization within this complex octoploid, and chromosome painting revealed them as genomic variants constructed de novo from the parental species represented in the hybrid (Pasakinskienė and Jones, 2005). In this study we extended our knowledge obtaining sequence data from the particular regions of nuclear rDNA ITS and cpDNA gene and intergenic sites, namely matK gene and trnH-psbA, trnL-trnF and rpS12-rpL20, of four genotypes recovered from re-diploidization. The obtained sequence data has demonstrated ITS, trnH-psbA and trnL-trnF sequences were useful in tracing the species identity, while rpS12 - rpL20 and matK revealed individual differences between the genotypes. These studies carried out in rDNA ITS and cpDNA regions disclose the complexity of the ‘novel diploids’ and suggest us with a particular scenario(s) of genome reconstruction in the distant plant hybrids.