Identification of parental chromosomes and detection of ribosomal DNA sequences in interspecific hybrids of Lilium revealed by multicolor in situ hybridization

In wide interspecific crosses of lily, different hybrid groups were used viz., L. longiflorum (L), Asiatic hybrids (A) and Oriental hybrid (O). Two BC₁ plants, OLA and OLO, were derived from crossing Oriental hybrids as a mother to LA and LOLO hybrids as male parent. LA and LOLO F₁ hybrids were known to produce 2n-gametes (<9.6%) and 2x-gametes (>40%), respectively. GISH enabled unequivocally the identification of parental chromosomes. Both BC₁ progeny, OLA and OLO, possessed three genome sets with 36 chromosomes (2n=3x=36) without any intergenomic recombinations. 45S rDNA probe was successfully hybridized on NOR bearing chromosomes of L. longiflorum and Oriental hybrid. L. longiflorum possessed 3 rDNA signals on chromosome 3, 4 and 7. Chromosome 3 of L. longiflorum showed one signal near to the secondary constriction on the long arm. 9 chromosomes of Oriental hybrid showed one or two hybridization signals indicating some extent of polymorphism. This polymorphism confirmed the fact that Oriental hybrids are mixed with several species in the section Archelirion. Based on result of the polymorphism of the rDNA signal, the origin of some chromosome number of Oriental hybrid could be assumed.