In Situ Chromosomal Localization of rDNA Sites in “Safed Musli” Chlorophytum Ker-Gawl and Their Physical Measurement by Fiber FISH

Abstract

Fluorescence In Situ Hybridization (FISH) technique has been applied on somatic chromosomes and extended DNA fibers in the medicinally important species of Chlorophytum to elucidate physical localization and measurement of the rDNA sites using two rRNA multigene families homologous to 45S and 5S rDNA. The two species of Chlorophytum, namely C. borivillianum and C. comosum, both with 2n = 28, reveal diversity for copy number and localization of rDNA sites. C. borivillianum is comprised of five 45S-rDNA sites:one each in the secondary constriction region of chromosomes 7, 8, 9; one in the subtelomeric region of the short arm of chromosome 2 and the telomeric region of the short arm of chromosome 12; and one 5S-rDNA site in the subtelomeric region of the long arm of chromosome 1. In C. comosum, there are three 45S-rDNA sites (one each in the short arm of chromosomes 12, 13, and 14) and two 5S-rDNA sites (in the secondary constriction regions of chromosomes 2 and 13). Fiber FISH analysis conducted on extended DNA fibers revealed variation in the size of continuous tandem strings for the two r-DNA families. Taking the standard value of native B DNA equivalent to 3.27 kb for 1 mum, it was estimated that the physical size of continuous DNA strings is of the order of approximately 90 kb, 180 kb, and 300 kb for 45S-rDNA and of the order of 60 kb, 150 kb for 5S-rDNA in C. comosum, grossly in correspondence to their respective physical sizes at metaphase.

Physical mapping of rDNA and heterochromatin in chromosomes of 16 Coffea species: A revised view of species differentiation

“…congensis seems to be absent or not detected in C. arabica. The loss of rDNA locus in allotetraploid species, compared with their progenitors, has already been documented (Hanson et al 1996;Comai et al 2000;Krishnan et al 2001;Liu et al 2003;Lavania et al 2005). For Mishima et al (2002), 5S sites are often eliminated after polyploidization, while 18S sites seem to be more conserved.…”

Chromosomal localization of rDNA and DAPI bands in solanaceous medicinal plant Hyoscyamus niger L.

“…They may be unlinked on the same chromosome arm, or located on different chromosomes, but variation in locus size/copy number is known to occur across genotypes and geographical regions (Tagashira et al 2009). Although the occurrence of 5S rDNA sites has been shown to be associated with nucleolus in soybean, common bean (Shi et al 1996) and wheat (Mukai et al 1991), the occurrence of two rDNA gene families on the same chromosome as observed in Chlorophytum (Lavania et al 2005) as well as here is unusual and may serve as a marker to aid chromosome identification. In the last two decades, FISH studies have been conducted in numerous plant species to elucidate the number and localization of rDNA sites.…”

“…The detection of FISH signals was done according to Lavania et al (2005) by incubating the slides for 1 h at 37 • C in the detection mix. The biotinylated 45S DNA probe was detected by avidin DN conjugated with Cy3 (0.025% v/v), and digoxigenin-labelled DNA was detected by anti-digoxigenin (Fab fragment) conjugated with FITC (fluorescein isothiocynate, 1%) in 5% (w/v) BSA (borine serum albumin).…”

Micropropagation: A Tool for the Production of High Quality Plant-based Medicines

“…Four millimeter long shoot buds encapsulated in 3.0%sodium alginate matrix polymerized by 100mM solution of CaCl 2 .2H 2 O yielded best results. Recently, Fluorescence In Situ Hybridization (FISH) technique has been applied on somatic chromosomes and extended DNA fibers in the medicinally important species of Chlorophytum to elucidate physical localization and measurement of the rDNA sites using two rRNA multigene families homologous to 45S and 5S rDNA [47].…”