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The genetic relationship and diversity among four Typha taxa in East Asia were evaluated using amplified fragment length polymorphism (AFLP) markers. Three AFLP selective primer combinations generated a total of 707 amplification products, of which 704 (99.6%) were polymorphic. The unweighted pair-group method with arithmetic mean (UPGMA) dendrogram and principal component analysis (PCA) plot confirmed the taxonomic status of four separate species. East Asian Typha taxa separated into two groups: the first with Typha angustifolia and the second with T. orientalis , T. laxmanni , and T. latifolia with a high bootstrap value for UPGMA (93%) and a low first score for PCA (25%). The two clusters corresponded with two sections based on the bracteoles in the female flower: section Bracteolatae and section Ebracteolatae . T. angustifolia showed the highest genetic diversity among the four Typha taxa (percentage of polymorphic loci [ PPL ] = 71%, H o = 0.157), whereas T. latifolia had the lowest genetic diversity ( PPL = 40%, H o = 0.117). Genetic diversity was related to the presence of the gap between male and female inflorescences. A positive correlation between genetic distance and geographic distance was clearly found in the two species with continuous inflorescences ( T. latifolia and T. orientalis ). This positive correlation was not observed in the other species with discontinuous spikes ( T. angustifolia and T. laxmanni ).

Isoetes coreana Chung and Choi is on the list of critically endangered species in South Korea. Using randomly amplified polymorphic DNA (RAPD) markers, we investigated the genetic diversity within and between seven local populations of I. coreana . Ten RAPD primers produced a total of 94 bands, of which 59 (62.8%) were polymorphic. A low level of genetic diversity was recognized within the populations of I. coreana : polymorphic loci ( P ), with values ranging from 3.4% to 33.9%, and a mean value of 15.5% being observed. Analysis of molecular variance (AMOVA) showed that genetic diversity was greater among populations (81.6%) than within populations (19.7%) or among the three regions included in this study (Han River, Youngsan River, and Nakdong River). In addition, a high degree of genetic differentiation ( θ B = 0.742) was detected among the populations. These results indicate that genetic differentiation has occurred very rapidly. However, the rate of gene flow between populations was found to be as low as 0.059, irrespective of the genetic and geographical distances between the populations, which indicates that genetic drift must have played an important role in forming the present populations of I. coreana . Because a reduction of genetic diversity as a result of genetic drift is undesirable, increasing the gene flow between populations of Korean quillwort I. coreana should be considered as a conservation strategy.