Identification of genome relationships among Paphiopedilum species by genomic and fluorescent in situ hybridization

In the present report, the genomic relationships among the species of Paphiopedilum were investigated by fluorescent in situ hybridization (FISH) using both total genomic DNA (GISH) and 45S ribosomal RNA genes (rDNA) as probes. The number and location of 45S rRNA genes varied among the species of Subgenus Parvisepalum. In P. emersonii and P. hangianum, two pairs of chromosomes bearing 45S rDNA loci were detected; while in P delenatii and P. micranthum, one pair of chromosome bearing 45S rDNA locus was found. For the other species, one pair of chromosome has 45S rDNA and was usually visualized with fluorescing signal by FISH method. In the interspecific hybrids (P. delenatii x P. glaucophyllum), genomic in situ hybridization provides clear identification of the parental origin of chromosomes. A better understanding of the genomic relationships of species in the genus will aid valuable conservation and efficient utilization of the genetic resource in Paphiopedilum.