Isolation and characterization of a satellite DNA family in the Saccharum complex Karine Alix, Franc-Christophe Baurens, Florence Paulet, Jean-Christophe Glaszmann, and Angélique D’Hont Abstract: EaCIR1, a 371-bp Erianthus-specific satellite DNA sequence, was cloned from TaqI restricted genomic DNA after agarose-gel electrophoresis. This sequence has 77% homology with a 365-bp satellite of Helictotrichon convolutum and 72% homology with a 353-bp tandem repeat sequence from Oryza sativa. PCR primers defined in the conserved regions of these repetitive sequences were used to isolate other satellite DNAs in different representatives of the Saccharum complex: SoCIR1 in Saccharum officinarum, SrCIR1 in Saccharum robustum, SsCIR1 and SsCIR2 in Saccharum spontaneum, and MsCIR1 in Miscanthus sinensis. EaCIR1 and SoCIR1 were localized to subtelomeric regions of the chromosomes by fluorescence in situ hybridization. Southern hybridization experiments, using two representatives of this repeat sequence family as probes, illustrated contrasting species-specificity and demonstrated the existence of similar repetitive elements in sorghum and maize. Key words: satellite DNA, sugarcane, Saccharum complex, Gramineae, fluorescence in situ hybridization, FISH. Résumé : La migration électrophorétique, sur gel d’agarose, de fragments résultant d’une restriction par l’endonucléase TaqI d’ADN génomique, a permis d’isoler un ADN satellite de 371 pb spécifique du genre Erianthus, EaCIR1. Cette séquence présente 77% d’homologie avec un ADN satellite de 365 pb spécifique de Helictotrichon convolutum, ainsi que 72% d’homologie avec une séquence répétée en tandem de 353 pb spécifique de Oryza sativa. Des amorces PCR définies dans les zones conservées de ces séquences répétées ont permis d’isoler d’autres ADN satellites chez différents représentants du complexe Saccharum : SoCIR1 chez Saccharum officinarum, SrCIR1 chez Saccharum robustum, SsCIR1 et SsCIR2 chez Saccharum spontaneum ainsi que MsCIR1 chez Miscanthus sinensis. EaCIR1 et SoCIR1 ont été localisés dans les régions subtélomériques des chromosomes, par hybridation in situ en fluorescence. La réalisation d’hybridations de type Southern, en utilisant deux représentants de cette famille de séquences répétées comme sondes, a illustré l’existence de la spécificité d’espèce de ces satellites, et démontré l’existence d’éléments répétés similaires chez le sorgho et le maïs. Mots clés : ADN satellite, canne à sucre, complexe Saccharum, Graminées, hybridation in situ en fluorescence, HISF. Alix et al. 864 Sugarcane is a Gramineae of the Andropogoneae tribe and belongs to the genus Saccharum, which comprises six spe- cies characterized by a high ploidy level and aneuploidy. Saccharum officinarum (2n = 80) is a high sugar producer that was domesticated in New Guinea, probably from Saccharum robustum (2n = 60, 80, and 63–200) (Daniels and Roach 1987), a wild species with a natural distribution from Borneo to the New Hebrides (Price 1965). Saccharum spontaneum (2n = 40–128) is a wild highly polymorphic species growing in the tropics and subtropics, from Africa to the Salomon Island, with India as the center of origin (Daniels et al. 1975). Saccharum barberi (2n = 81–124) and Saccharum sinense (2n = 111–120) are presumed to be of interspecific origin, involving S. officinarum and S. spontan- eum crosses, and were cultivated in North India and China, respectively. Saccharum edule (2n = 60, 70, and 80), thought to possess intergeneric origins, is a marginal form of sugarcane, cultivated as a vegetable. In addition to those already mentioned, Saccharum is as- sociated with four other genera: Erianthus (sect. Ripidium), Miscanthus (sect. Diantra), Sclerostachya, and Narenga, to constitute the “Saccharum complex,” a closely related inter- breeding group suggested to be involved in the origin of sugarcane (Mukherjee 1954, 1957; Daniels and Roach 1987). Modern sugarcane cultivars (Saccharum spp., 2n = 110–130) arose from interspecific crosses made at the begin- ning of this century, involving principally S. officinarum and S. spontaneum clones. The number of parental clones impli- cated in the breeding of these hybrids is relatively restricted (Arceneaux 1965). This limited genetic basis could be the reason for the present slow progress being made in sugar- Genome 41: 854–864 (1998) © 1998 NRC Canada 854 Corresponding Editor: J.H. de Jong. Received November 24, 1997. Accepted May 12, 1998. K. Alix, F.-C. Baurens, F. Paulet, J.-C. Glaszmann, and A. D’Hont. 1 Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), avenue Agropolis, BP 5035, F-34032 Montpellier Cédex 1, France. 1 Author to whom all correspondence should be addressed (e-mail: dhont@cirad.fr).