01073nas a2200181   4500008004100000245007100041210006700112260001200179300001400191490000700205520049900212653001500711653001200726653001000738653001000748100001700758856011600775       2000                        eng d00aIsoetes sinensis var. Sinensis in Korea (Isoetaceae: Pteridophyta)0 aIsoetes sinensis var Sinensis in Korea Isoetaceae Pteridophyta  c2000///  a169 - 1770 v163 aQuillworts recently collected from a population on Cheju Island, South Korea, are tetraploid (2n = 44 = 22II) and have cristate megaspores and echinate microspores. Based on these characters, the specimens are identified as Isoetes sinensis var. sinensis, a globally rare taxon previously unreported in Korea. The apparently close taxonomic relationship between Korean I. sinensis var. sinensis and the basic diploid I. taiwanensis suggests that further phylogenetic investigation is warranted.10aChromosome10aIsoetes10aKorea10aSpore1 aTakamiya, M.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0039174448&partnerID=40&md5=8986e80438e25ba35955cf46aa7ed4f701363nas a2200253   4500008004100000245011200041210006900153260001200222300001600234490000700250520054000257653002100797653001500818653002800833653002000861653001700881653001400898653001800912100001400930700001400944700001900958700001600977856011600993       2000                        eng d00aCasparian strips in the leaf intrastelar canals of Isoetes duriei bory, a mediterranean terrestrial species0 aCasparian strips in the leaf intrastelar canals of Isoetes durie  c2000///  a1051 - 10540 v863 aAnatomical observations, using light and fluorescence microscopy, were made on leaves of Isoetes duriei to verify the presence of casparian bands around the intrastelar canals. This peculiar anatomical feature, previously reported for some Isoetes species, is confirmed. The possible role of this endodermis-like structure, in the transport of water due to root pressure or in the accumulation of certain metabolites, is discussed in relation to the ecological and anatomical features of the species. (C) 2000 Annals of Botany Company.10aCasparian strips10aEndodermis10aFluorescence microscopy10aIsoëtes duriei10aLeaf anatomy10aLycopsida10aMediterranean1 aRomeo, D.1 aTroia, A.1 aBurgarella, C.1 aBellini, E.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0033765118&partnerID=40&md5=a1f956e770d2b3c59c0ac85d579f7c9c02894nas a2200145   4500008004100000245009000041210006900131260001200200300001400212490000700226520236600233100001702599700001602616856011602632       2000                        eng d00aIsozymes of the Isoetes riparia complex, II. Ancestry and relationships of polyploids0 aIsozymes of the Isoetes riparia complex II Ancestry and relation  c2000///  a260 - 2800 v253 aIsoetes riparia is a complex tetraploid taxon of eastern North America that in its widest sense includes a diversity of morphotypes variously segregated, or included in a single polymorphic species. Although the diploid ancestry of I. riparia has been proposed as I. echinospora x engelmannii, it is uncertain whether this ancestry applies to all elements of the complex, here broadly defined to encompass three segregates of I. riparia and the recently described I. hyemalis (referred to informally as riparia, canadensis, saccharata and hyemalis). To help clarify relationships among these tetraploids, isozyme genotypes for 13 loci coding eight enzymes, were determined for 16 populations representing all four segregates. Duplicate gene expression, evidenced as fixed heterozygosity consistent with allopolyploidy, characterized the tetraploid genotypes of all taxa. Although exhibiting modest to no variation within populations, populations were highly differentiated, most showing a unique combination of alleles for their multilocus genotypes, with the exception of five genetically identical Canadian populations. Ancestry was evaluated through comparison to diploid genotypes previously reported. A quantitative approach was carried out to rank likelihoods for hypothetical ancestral combinations of diploids for each tetraploid population. The ancestry I. echinospora x engelmannii hypothesized for I. riparia was unequivocally supported for the six populations of the most northern segregate, canadensis. Diploid ancestries for the remaining 10 more southern populations were less certain, although the diploid I. mattaponi was implicated as a likely ancestor for most. Most likely ancestry for populations of riparia/saccharata was inferred as I. valida x mattaponi, and for hyemalis as I. mattaponi x flaccida. However, these hypotheses were only slightly more likely than other combinations. UPGMA analysis using Rogers' similarity resulted in three clusters corresponding to canadensis, riparia/saccharata, and hyemalis. However, the hyemalis cluster was weakly associated and was not supported by UPGMA using Nei's identity. These highly variable tetraploid genotypes suggest a complicated evolutionary history for the I. riparia complex that probably involved a combination of diverse ancestry, multiple origins, divergence, and gene silencing.1 aCaplen, C.A.1 aWerth, C.R.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0034046198&partnerID=40&md5=48c688dd1d8bd2bf3f8bc0a92bc0306001342nas a2200145   4500008004100000245011500041210007000156260001200226300001200238490000700250520078800257100001501045700002001060856011601080       2000                        eng d00aThe chloroplast genome structure of the vascular plant Isoëtes is similar to that of the liverwort Marchantia0 achloroplast genome structure of the vascular plant Isoëtes is si  c2000///  a51 - 590 v903 aRestriction site mapping was used to characterize the chloroplast genome of the lycophyte, Isoëtes melanopoda. The Isoëtes chloroplast genome is approximately 139-145 kb in size with an inverted repeat of 12-13 kb. The gene content and consensus gene order are similar to that of Marchantia. A distinctive feature of the Isoëtes genome is an increased size of the small single copy (SSC) region possibly due to the insertion of a piece of DNA (3-8 kb) of unknown composition. The inferred insertion, along with a slightly larger inverted repeat, are responsible for the apparent size difference in the total genome relative to Marchantia. Patterns of restriction fragments were also consistent with the presence of a small inversion (2-3 kb) in the large single copy (LSC) region.1 aDuff, R.J.1 aSchilling, E.E.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-9944243780&partnerID=40&md5=3fb650c66f2ac19a030f74b0002f62dd02139nas a2200145   4500008004100000245010100041210006900142260001200211300001400223490000700237520160000244100001701844700001601861856011601877       2000                        eng d00aIsozymes of the Isoetes riparia complex, I. Genetic variation and relatedness of diploid species0 aIsozymes of the Isoetes riparia complex I Genetic variation and   c2000///  a235 - 2590 v253 aIsozymes were examined in the six aquatic (including amphibious) diploid species of Isoetes of eastern North America in order to quantify their levels and patterns of genetic variation, to determine their genetic distinctness, and to evaluate the utility of allozymes in addressing ancestry in the I. riparia complex. Twenty-six populations representing diploid species, I. echinospora, I. engelmannii, I. flaccida, I. mattaponi, I. prototypus, and I. valida were compared for eleven enzymes coded by 16 interpretable loci. Levels of genetic variation in populations tended to be low ranging from none (means: P = 0.0, A = 1.0, H = 0.0) in I. echinospora to moderate (means: P = 22.9, A = 1.4, H = 0.093) in I. flaccida. Genetic variation in polymorphic species tended to be distributed more among than within populations, as indicated by high F(st) values (F(st) > 0.607 in all polymorphic species except I. mattaponi, for which F(st) = 0.272). The genetic identities of conspecific populations were high, with mean values ranging from I = 0.779/S = 0.733 in I. flaccida to I = 1.000/S = 1.000 in I. echinospora. Interspecific genetic identities were lower, with means ranging from I = 0.438/S = 0.429 between I. mattaponi and I. prototypus to I = 0.736 between I. valida and I. flaccida, and S = 0.699 between I. valida and I. prototypus. Thus the six diploids were found to be genetically distinct, corroborating their recognition based on morphology. Evidence from this study indicates that isozymes may be informative in diagnosing ancestry of allopolyploids in the Isoetes riparia complex.1 aCaplen, C.A.1 aWerth, C.R.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0034042682&partnerID=40&md5=ed389e88047f4d191722332cdcce26a9