02233nas a2200241   4500008004100000245008100041210006900122260001200191300001600203490000800219520151000227653001201737653001601749653001201765653001901777653001301796653001501809653001501824653000901839100001401848700001301862856011601875       2001                        eng d00aBasal meristem and root development in Isoetes asiatica and Isoetes japonica0 aBasal meristem and root development in Isoetes asiatica and Isoe  c2001///  a1225 - 12350 v1623 aWe studied the anatomy of the basal meristem and root development in Isoetes asiatica and Isoetes japonica to better understand the Isoetes rhizomorph, an enigmatic organ. The basal (root-producing) meristem of the rhizomorph is continuous with the lateral meristem, and both comprise a single meristem. The basal meristem with a layer of thin initials has both organogenetic and thickening meristem attributes. A combination of these attributes indicates that the basal meristem is distinctive among the vascular plant meristems, including cambium. The root primordia develop from young derivative cells organized in three to four radial fines, and their main body is composed of a three-layered apical meristem. The primordia, unlike the roots, produce a small number of derivative cells as well as a procambium and future root cap, and they do not form a cortex and epidermis. Prior to developing into roots, the primordia are shifted closer to the corm surface through further development of cortical tissues from the basal meristem and sloughing of surface cells. This unique developmental pattern is established through the subendogenous origin of the second embryonic root and the endogenous origin of the third root. The meristem and pattern of root development in Isoetes is compared with that indicated for the lepidodendrid and isoetalean rhizomorphs and contrasted with that in the Selaginella rhizophore. The comparison seems not to support the interpretation of the roots as leaf homologues.10aCambium10aDevelopment10aIsoetes10aLepidodendrids10aMeristem10aRhizomorph10aRhizophore10aRoot1 aYi, S.-Y.1 aKato, M.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0034749638&partnerID=40&md5=1887916a18c476c09780d6d6ad7f78b602543nas a2200229   4500008004100000245016000041210006900201260001200270300001400282490000800296520175700304653000902061653001202070653002202082653001202104653001402116653002502130100001202155700001302167700001602180856011702196       2009                        eng d00aGenetic diversity and population structure of diploid and polyploid species of isoetes in east asia based on amplified fragment length polymorphism markers0 aGenetic diversity and population structure of diploid and polypl  c2009///  a496 - 5040 v1703 aIsoetes L. is critically endangered in areas of East Asia, including Taiwan, Japan, and South Korea. The genetic diversity and the population structure of six Isoetes species from East Asia were evaluated by using amplified fragment length polymorphism (AFLP). Three AFLP-selective primer combinations generated a total 923 amplification products, of which 919 (99.6%) were polymorphic. The levels of genetic diversity of two diploid species (I. taiwanensis [percentage of polymorphic loci (PPL) = 33.1%-38.3%] and I. asiatica [PPL = 49.0%]) are higher than those of polyploid species (tetraploid: I. jejuensis [PPL = 9.3%-29.3%] and I. hallasanensis [PPL = 22.3%]; hexaploid: I. coreana [PPL = 1.6%-20.6%] and I. japonica [PPL = 5.6%-20.5%]). Higher genetic differentiation was detected for populations of I. coreana (0B = 0.730) than for the diploid species I. taiwanensis (0B = 0.074). In addition, analysis of molecular variance showed that a large proportion (79.8%) of genetic differentiation existed among population of I. coreana. However, 93.2% of the total genetic variation was attributed to differentiation within populations of I. taiwanensis. A neighbor-joining dendrogram resulted in three clusters, one for I. asiatica, one for I. japonica, and one for the rest of the species, subdivided into two: (1) I. taiwanensis/I. jejuensis and (2) I. coreana/I. hallasanensis. Furthermore, individuals from each population of I. coreana and I. jejuensis were clustered into population-specific subclusters. The probable causes of the current pattern of genetic variation and population structure are discussed, and suggestions on the future protection of Isoetes species are also given. © 2009 by The University of Chicago. All rights reserved.10aAFLP10aDiploid10aGenetic diversity10aIsoetes10aPolyploid10aPopulation structure1 aKim, C.1 aShin, H.1 aChoi, H.-K.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-67649230633&partnerID=40&md5=794650fbe3653559e7cb90004dfa45c6