-\a- Euplrytica l20z 273-280,2001. ttT O 2001Kluwer AcademicPublishers. Printed in theNetherlands. 273 RAPD analysis of interspecific relationships in presumably apomictic Cotoneaster species Igor V. Bartishl,3, Bertil Hylmo2 & Hilde Nyboml r Balsgdrd-Department of Horticultural Plant Breeding, Swedish University of Agricultural Sciences, Fjcilkestads- vrigen 123-1, SE-291 94 Kristianstad, Sweden; zBygatan 30,SE-267 40 Bjuv, Sweden; 3present address: I nstitute of Botany, Academy of Sciences, CZ-25243 Pruhonice l, Czech Republic Received 28 March 2000; accepted 12 September 2000 Key words; apomixis, Cotoneasrer, DNA marker, plant breeding, systematics, taxonomy Summary A few of the approximately 300 Cotoneaster species described are diploid but the majority appeaÍ to be polyploid. The occurrence of apomixis in polyploid Cotoneaster species has been reported but never proven with genetic markers. We have used 76 polymorphic RAPD markers to investigate the breeding system and phenetic grouping of some critical taxa, including a total of 19 plant accessions representing 13 mostly European species in the series Cotoneaster.Three to four individual plants, raised from seed from the same original plant, were analyzed for each of three accessions to investigate the possible occuffence of apomictic seed set. Absolutely congruent RAPD profiles were encountered among seedlings from one accession, whereas we found one or two marker differences among seedlings from the other two accessions. Genetic similarities among the different accessions were analyzed with a UPGMA-derived dendrogram. The most deviant taxon was the Chinese C. albokermesinus. A group with C. soczavianus and C. tomento,srr,s was rather isolated from the remainder, as was also C. kullensis. Among the remaining taxa, two well supported clusters were found: (1) C. antoninae and C. uralensis, anď (2) C. integerrimus and C. raboutensis, whereas the other five species (C. canescens, C. niger, C. scandinavicus, C. juranus, C. cambricas) formed a poorly supported cluster with no clear substructuring. A principal coordinate analysis yielded results that were in good conespondence with the dendrogram. Agďn C. albokermesinus appears to be totally isolated from the other species. In addition, two well-defined and rather isolated groups were found: (1) C. tomentosus and C. soczavianus, and (2) C. antoninae and C. uralensis, with the remďnder comprising a loosely defined group. Introduction The Rosaceous genus Cotoneasler consists of woody plants, varying in stature from 0.2 m prostrate shrubs to 15-20 m trees, and occurring all over Europe, North Africa and temperate parts of Asia excluding Japan. A pronounced distribution center is found in the Chinese provinces Yiinnan and Sichuan.Many Co- toneaster species have become popular ornamentals due to their attractive foliage, abundant flowers and, especially, for their bright red (or sometimes black) fruits. Numerous cultivars have been developed and are frequently planted in temperate and warm tem- perate areas. Evergreen species are planted in warmer areas, whereas mostly deciduous species are planted in colder a.reas where some species can withstand ex- tremely low winter temperatures. The popularity of the genus is demonstrated by Stace (1997) who describes 67 species as garden escapes in his Flora of the British Isles. Some Cotoneaster speciesare diploid,2n= 34,but the majority appear to be polyploid, most often tet- raploid, 2n = 68 (Zeilinga, 1964; Kriigel, 1992). The number of recognized species has increased consider- ably in recent years, with rnany new species described on material brought in from China and Himalaya. Re- hder (1927) mentions 80 species, Flinck & HylmÓ (1966) 176 speciesand Phipps et al. (1990) 261 spe-