Physical Mapping of 18S rDNA by Fluorescence in situ Hybridization (FISH) in the Three Species of the Genus Paris L., Liliacea.

Abstract

Summary 18S ribosomal RNA gene (rDNA) loci were mapped on chromosomes of Paris tetraphylla A. Gray, P. verticillata M. v Bieberstein and P. polyphylla Smith, Liliaceae by using fluorescence in situ hybridization (FISH). The 18S rDNA probes were prepared from the interphase nuclei by the method during the polymerase chain reaction (PCR). Chromosome numbers of all the examined plants were 2n=10. Haploid genomes of P. tetraphylla and P. verticillata were consisted of three metacentric chromosomes, a submetacentric chromosomes and an acrocentric satellite chromosome. One 18S rDNA locus was detected at the second constriction of the acrocentric chromosome. On the other hand, a haploid genome of P. polyphylla was consisted of three metacentric chromosomes and two acrocentric chromosomes. Two 18S rDNA loci were detected at the second constriction of both acrocentric chromosomes. Key words rDNA, Fluorescence in situ hybridization (FISH), Paris, Liliaceae.Paris L. is a perennial herb which is found from Europe to the Far East. P. tetraphylla A. Gray is an endemic species in Japan, while P. verticillata M. v Bieberstein is distributed over China , Korea, Kurill Islands, Manchuria, Sakhalin and Japan. P. polyphylla Smith and its related taxa grow in the mainland China and Formosa. Karyotypes of the Asian species of Paris have been studied by several researchers (Gotoh 1933, Haga 1934, Hara 1969, Kayano 1961, Kurabayashi 1952, Kurabayashi and Samejima 1953, Miyamoto and Kurita 1990, 1994, Miyamoto et al . 1991, 1992, Noda 1963, Stow 1935, Suzuki and Yoshimura 1986, Uchino and Wang 1996, 1997. The standard chromosome numbers are 2n= 10 (2x) in P. tetraphylla, P. verticillata and P. polyphylla. The karyotypes of P. tetraphylla and P. verticillata are consisted of three pairs of metacentric chromosomes, a pair of submetacentric chromosomes and a pair of acrocentric chromosomes, while that of P. polyphylla consists of three pairs of metacentric chromosomes and two pairs of acrocentric chromosomes. A differential staining pattern of chromosomes of the genus Paris was reported (Darlington and La Cour 1938, Kurabayashi 1952, Noda 1963. Then, patterns of the C-banding and the fluorescent banding by using 4',6-diamidino-2-phenylindole (DAPI) were studied in Paris (Miyamoto and Kurita 19901994, Miyamoto et al. 1991, 1992. As a result, it is concluded that the heterochromatic regions which were revealed by the C-banding methods vary both in stainability with DAPI and the structural appearance.Recently, fluorescence in situ hybridization (FISH) offers a superior method for detection of molecular differentiation of chromosomal organization (Fukui et al . 1994a, Ohmido and Fukui 1995, 1997. In the present study, we report the 18S rDNA loci in three diploid species of the genus Paris by using FISH with direct-cloned probes.