Chromosome characterization and physical mapping of 18S rDNA in Lilium longiflorum originated interspecific hybrids using combined genomic and fluorescent in situ hybridization

Abstract

This study was aimed at differentiating parental genomes, examining intergenomic composition, and mapping mitotic metaphase chromosomes by localizing parental and 18S rDNA probes in seven interspeci c hybrid progenies that originated from Lilium longi orum. Since in situ hybridization has not been previously used in lily breeding, ow cytometry was used in conjunction with genomic and uorescent in situ hybridization to determine the genomic contribution of each parent to the interspeci c progenies. A signi cant variation was observed in the DNA content, chromosome length, and 18S loci in F 1 as compared to the female and male parents. L. longi orum showed nearly two times higher DNA content than the male parents and L. longi orum × Asiatic progenies, but eight times higher than L. longi orum × L. hansonii. Genomic in situ hybridization results revealed that both female and male parents contributed an equal number of chromosomes to their interspeci c F 1 offspring. Fluorescent in situ hybridization mapping revealed that 18S rDNA had 8, 6 and 7 loci in L. longi orum parents, i.e., White heaven, Bright tower, and White tower, respectively, whereas each Asiatic cultivar and L. hansonii used as male showed 8 and 12 loci respectively. Interspeci c progenies showed 8 and 7 loci in LA, and 10-11 in LM hybrids. These cytogenetic results implied equal genetic and chromosomal contribution from both parents to their intergenomic progenies. Therefore, this combined (Schwarzacher et al., 1992)cytogenetic method has the potential to be an affordable and time-saving approach in lily breeding that could determine the status of hybrids and their genomic origin while achieving physical mapping and detecting genes in different genomes.