GISH analyses of backcross progenies of two Lilium species hybrids and their relevance to breeding

A total of 21 BC1 progenies of Oriental × Trumpet (OT) Lilium hybrids, nine BC2 progenies of OT hybrids, and three BC1 progenies of Martagon × Asiatic (MA) hybrids were analysed using genomic in situ hybridisation (GISH). Of the BC1 progenies of the OT hybrids, 15 were euploid (14 triploids, 2n = 3x = 36; 1 diploid, 2n = 2x = 24), and six were aneuploid. The triploid progenies had resulted from 2n eggs due to first division restitution (FDR). The aneuploid progenies had resulted from viable aneuploid gametes. All the BC2 progenies of triploid (2n = 3x = 36) OOT hybrids were aneuploid. Chromosome numbers in the BC2 progenies varied from 25 to 29.Two out of three BC1 progenies of the MA hybrids were aneuploids, with 35 and 32 chromosomes, respectively. Another was a triploid (2n = 3x = 36) which had resulted from 2n eggs due to indeterminate meiotic restitution (IMR). GISH revealed extensive intergenomic recombination in the BC1 progenies of OT and MA hybrids. A large number of Trumpet or Martagon chromosome segments were transmitted to the BC1 progenies from the F1 OT or MA hybrids. However, very few Trumpet chromosome segments were transmitted from the triploid BC1 parent to the BC2 progenies. These results indicate that it should be possible to select cultivars which possessed both traits from these BC1 progenies and they would be fertile.