Clonality in wild rice (Oryza rufipogon, Poaceae) and its implications forconservation management

Correlations were examined between habitat characters and clonal structures determined by the RAPD (random amplified polymorphic DNA) assay in five po pulations of Oryza rufipogon in China. Nine of 175 decameric primer were us ed in the study because they reproducibly amplified polymorphisms. The exte nt of clonality together with the clonal and sexual reproductive strategies varied greatly among the five populations and correlated with the habitats where they occur. The populations under serious disturbance or seasonal dr ought tended to have small clones with relatively high clonal diversity cau sed by sexual reproduction. whereas the populations with little disturbance and sufficient supply of water were prone to have large clones with relati vely low clonal variation and low sexual reproduction. Therefore, the dynam ics of sexual vs. clonal reproduction of this species depended mainly on en vironmental factors, such as external disturbance and water supply, rather than latitudes indicated by previous study. These result!, have important i mplications for in situ conservation of O. rufipogon. Adequate external dis turbance and water supply control are essential for maintaining high clone diversity of in situ conserved populations. According to the extent of clon ality of the populations examined. we recommend that an interval of > 12 m should be required for collecting samples Tor ex situ conservation and for population genetic studies to capture possible genetic diversity for O. ruf ipogon in China.