@article {129,
	title = {Biosystematic studies on the genus Isoetes (Isoetaceae) in Japan. II. Meiotic behavior and reproductive mode of each cytotype},
	journal = {American Journal of Botany},
	volume = {83},
	year = {1996},
	note = {Cited By (since 1996):13Export Date: 11 November 2013Source: Scopus},
	month = {1996///},
	pages = {1309 - 1322},
	abstract = {Meiotic 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.},
	keywords = {Chromosome, Hybrid, Isoetes, megasporogenesis, meiosis, microsporogene sis, polyplo id, reproductive mode},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0030475989\&partnerID=40\&md5=996182a1723b75d447e3a2137006f7bd},
	author = {Takamiya, M. and Watanabe, M. and Ono, K.}
}
