Analysis of clonal structure of Melaleuca cajuputi (Myrtaceae) at a barren sandy site in Thailand using microsatellite polymorphism

The clonal structure of Melaleuca cajuputi growing in Thailand was investigated using ten polymorphic microsatellite markers and excavation of root connections. A large-scale test plot (25x45 m) and a small-scale one (10x12 m) within it were established in an M. cajuputi population at a barren sandy location in Narathiwat, southern Thailand (6 degrees 30' N, 101 degrees 45' E). Eleven clonal groups were identified from 31 ramets in the small-scale test plot based on root connections between ramets. To evaluate the effectiveness of microsatellite markers for genet analysis of M. cajupuri, clonal groups in the small-scale test plot identified by root connection were compared with genets determined by analysis of ten microsatellite markers. Most of the clonal groups identified by root connection completely matched the genets determined by the microsatellite markers. This indicates that microsatellite markers are very useful for genet analysis of M. cajuputi. Eleven genets were identified from 53 ramets in the large- and small-scale test plots using the ten microsatellite markers; the largest genet was about 23 m wide. This suggests that vegetative reproduction, i.e., shoot sprouting from roots, plays an important role in the establishment of M. cajuputi populations at this barren sandy site.