ASSESSMENT OF GENETIC-RELATIONSHIPS AMONG RHODODENDRON SPECIES, VARIETIES AND HYBRIDS BY RAPD ANALYSIS

Randomly amplified polymorphic DNA (RAPD) markers have the potential to reveal genetic similarity among plants. RAPD profiles of thirteen rhododendron hybrids, species and cultivars were analyzed to study their genetic relationships. The cluster analysis grouped together varieties and/or hybrids in accordance with their known genetic relationship. For instance, two varieties of Rhododendron yakushimanum, var. Mist Maiden and var. Ken Janeck, clustered together while R. yakushimanum var. Pink Parasol clustered with a hybrid of Pink Parasol X Rhododendron smirnowii. These three varieties and the hybrid then clustered with R. smirnowii. Similarly, the other hybrids with common parents showed a closer genetic relatedness with each other than with other rhododendrons. The sequence homology of two amplification products was studied by Southern hybridization. The amplification fragment OPL07(660) of four Rhododendron species, Rhododendron Anna Baldsiefens, Rhododendron arborescens, Rhododendron atlanticum, and Rhododendron poukhanense were homologous to each other. In contrast to this, amplification product OPL03(900) of R. Anna Baldsiefens has no homology to any other amplification product. The genetic relationship revealed from cluster analysis on the basis of RAPD profiles was similar to their known genetic makeup.