02381nas a2200253   4500008004100000245013000041210006900171260001200240300001600252490000700268520155900275653001501834653001101849653001201860653002101872653001201893653002301905653001501928653002201943100001701965700001701982700001201999856011602011       1996                        eng d00aBiosystematic studies on the genus Isoetes (Isoetaceae) in Japan. II. Meiotic behavior and reproductive mode of each cytotype0 aBiosystematic studies on the genus Isoetes Isoetaceae in Japan I  c1996///  a1309 - 13220 v833 aMeiotic behaviors and reproductive modes of Japanese Isoetes were studied. The hexaploid (2n = 66) and the octaploid (2n = 88) of I. japonica consistently formed 33 and 44 bivalents, respectively, at diakinesis and/or metaphase I in both micro- and megaspore mother cells. The tetraploid (2n = 44) of I. sinensis formed 22 bivalents and its hexaploid made 33 bivalents in both types of spore mother cells. At diakinesis and/or metaphase I of microspore mother cells in I. asiatica with 2n = 22, 11 bivalents were detected. Because behaviors of meiosis in all cytotypes mentioned above were quite regular and plants yielded normal-appearing spores, they should reproduce sexually. Aneuploids of I. japonica with 2n = 87 formed 43 bivalents and one univalent, and I. sinensis with 2n = 65 formed 32 bivalents and one univalent in microspore mother cells. Meiosis of both cytotypes was almost regular and yielded microspores of normal appearance. In the heptaploid (2n = 77) of I. japonica, a configuration of 22 bivalents and 33 univalents was detected in micro- and megaspore mother cells, and various irregularities were observed throughout the meiotic divisions. Therefore, the genomic formula of the heptaploid is symbolized as AABBCDE, and the heptaploid is a sterile F 1 hybrid between the hexaploid (AABBCC) and the octaploid (AABBDDEE) of I. japonica. Since diploid and even-numbered polyploids regularly formed bivalents and odd-numbered ones displayed irregularities, allopolyploidy should act as a significant speciation mechanism in this genus.10aChromosome10aHybrid10aIsoetes10amegasporogenesis10ameiosis10amicrosporogene sis10apolyplo id10areproductive mode1 aTakamiya, M.1 aWatanabe, M.1 aOno, K.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0030475989&partnerID=40&md5=996182a1723b75d447e3a2137006f7bd01073nas 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=8986e80438e25ba35955cf46aa7ed4f7