title: Species and genus specificity of the intergenic spacer (IGS) in the ribosomal RNA genes of Cucurbitaceae.
abstract: The use of intergenic spacer (IGS) fragments of plant ribosomal DNA (rDNA) for the differentiation between genera and species is tested by cross-hybridization experiments with different IGS probes of two Cucurbitaceae, Cucurbita pepo (zucchini) and Cucumis sativus (cucumber). Hybridization with cloned fragments of different parts of the IGS of ribosomal DNA exhibit a different degree of conservation within and between the Cucurbitaceae genera. In general, Cucurbita species seem to be closer related to each other than the Cucumis species. A repetitive element of the external transcribed spacer (ETS) shows a more genus-specific pattern, reacting only with the respective genera; the region preceding the ETS is conserved between the Cucurbita species but also cross-hybridizes weakly with the Cucumis species. A GC-rich element of the Cucumis sativus IGS ("Cfo-cluster") is present in small amounts in Cucumis melo (melon) and even less represented in other genera of the Cucurbitaceae.
authors.affiliation: Lehrstuhl für Allgemeine Genetik, Biologisches Institut, Universität Tübingen, Bundesrepublik Deutschland.
authors.forename: R A
authors.initials: RA
authors.lastname: Torres
authors.forename: U
authors.initials: U
authors.lastname: Zentgraf
authors.forename: V
authors.initials: V
authors.lastname: Hemleben
mesh_terms: D003433:Crosses, Genetic; D004275:DNA, Ribosomal / Q000235:genetics* / Q000302:isolation & purification; D009693:Nucleic Acid Hybridization; D010944:Plants / Q000235:genetics*; D012335:RNA, Ribosomal / Q000235:genetics*; D015183:Restriction Mapping; D013045:Species Specificity
chemical_list: D004275:DNA, Ribosomal; D012335:RNA, Ribosomal