Genetic variability and phytogeography of Miscanthus sinensis var. condensatus, an apomictic grass, based on RAPD fingerprints

DNA fingerprinting using random amplified polymorphic DNA (RAPD) markers wa s employed to investigate the genetic variation within and among population s of Miscanthus Anderss. sinensis var. condensatus (Hack.) Makino, an apomi ctic grass distributed along the coasts of Taiwan and Ryukyu Islands. A tot al of 250 plants from three Taiwanese populations (Southeast Coast, Orchid Islet, and Green Islet) and two populations from Ryukyu (Ishigaki and Amami -O-Shima Islets) were sampled. The amplified products of 40 random primers showed monomorphic banding patterns within all populations as well as among the three populations from Taiwan. Low genetic variation (with only two po lymorphic loci), but significant differentiation, was detected between popu lations from Taiwan and Ryukyu (Phi (CT) = 0.864) and between populations ( Phi (ST) = 1.0) from Ishigaki and Amami-O-Shima Islets. In contrast, a high level of variation was exhibited in the outcrossing Miscanthus sinensis va r. glaber (Nakai) Li. In addition to apomictic reproduction, low genetic va riation across populations of M. sinensis var. condensatus may be a result of high salinity acting as a selective agent. With the cost of reduced gene tic heterogeneity, apomixis may have provided a mechanism for avoiding the transmission of endophytic fungi. The phytogeographic pattern of M. sinensi s var. condensatus, as reflected by the RAPD data, likely represents isolat ion between Taiwan and Ryukyu since the mid-Pleistocene.