Genetic relationships in European and Asiatic Buxus species based on AFLP markers, genome sizes and chromosome numbers

The genetic relationships and diversity within the European and Asiatic Buxus species were analysed using AFLP, genome size analysis and chromosome counts. Based on these results two major clusters could be defined. One genetic cluster contained B. sempervirens and B. balearica, European species, and B. colchica, an Asiatic species but with leaf morphology similar to B. sempervirens. Species in this cluster were characterised by a genome size between 1.38 and 1.69 pg 2C(-1) and a chromosome number of 2n = 2x = 28 (diploid). Only four B. sempervirens cultivars within this cluster were triploid. A second cluster contained the Asiatic Buxus species B. microphylla, B. harlandii, B. hyrcana, B. myrica, B. henryi, B. bodinieri and B. wallichiana. Within this second genetic cluster three different ploidy levels could be observed. B. harlandii, B. hyrcana and nine B. microphylla cultivars were tetraploid (2n = 4x = 56) with a genome size of > 2.5 pg 2C(-1). Fifteen other B. microphylla cultivars were triploid (2n = 3x = 42). The other Asiatic Buxus species, B. henryi, B. bodinieri and eight B. microphylla cultivars, were diploid with a genome size of ca. 1.5 pg 2C(-1)