Location: Southern Horticultural ResearchTitle: Nuclear DNA content, base composition, and cytogenetic characterization of Christia obcordata) Author
Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/4/2013
Publication Date: 5/1/2013
Publication URL: http://handle.nal.usda.gov/10113/56750
Citation: Sakhanokho, H.F., Islam-Faridi, N. 2013. Nuclear DNA content, base composition, and cytogenetic characterization of Christia obcordata. Journal of the American Society for Horticultural Science. 138(3):205-209. Interpretive Summary: Christia obcordata, commonly known as butterfly plant, butterfly leaf, iron butterfly, butterfly stripe, or swallowtail, is an unusual and eye-catching plant with leaves that are usually tri-foliated and have the shape of striped butterfly wings. Because of its unusual and unique features, particularly its beautifully striped leaves, C. obcordata has clear ornamental potential. Unfortunately, not much scientific work has been done on this species to answer some basic questions. Therefore, we used conventional chromosome spread technique to determine the number of chromosomes in C. obcordata. Flow cytometry machine was used to determine its DNA content and genome size and applied fluorescent in situ hybridization to locate ribosomal RNA gene family in C. obcordata. The results of this study will contribute greatly to our understanding of the genetics of C. obcordata.
Technical Abstract: Christia obcordata is an intriguing small-sized house plant with unusual and attractive features such as its striped leaves. Because very little is known about the plant, we conducted an investigation of its genome and chromosomes. The number of chromosomes was determined using a protoplast technique to prepare root tip chromosome spread and was found to be 2n = 2x = 20. Flow cytometry was used to determine nuclear DNA content (1C = 0.65 pg = 634.4 Mb) for C. obcordata and AT/GC composition was shown to be AT%= 62.8% ± 0.0%and GC% = 37.2% ± 0.0%. Finally, fluorescent in situ hybridization was used to locate ribosomal RNA gene families in C. obcordata. Ribosomal RNA gene families, viz. 18S-28S and 5S rDNA, are unique cytomolecular landmarks that provide valuable information about the evolutionary organization of a genome. We have identified one locus each of 18S-28S and 5S rDNA. The 18S-28S rDNA is located in the subterminal position on the secondary constriction region [also known as the nucleolus organizer region (NOR)] and the 5S rDNA is located interstitially close to a centromeric position. The basic information gathered in this study on C. obcordata will be helpful in understanding the genetics of this species.