BIOSYSTEMATIC STUDIES ON THE GENUS ISOETES (ISOETACEAE) IN JAPAN .2. MEIOTIC BEHAVIOR AND REPRODUCTIVE MODE OF EACH CYTOTYPE

Citation
M. Takamiya et al., BIOSYSTEMATIC STUDIES ON THE GENUS ISOETES (ISOETACEAE) IN JAPAN .2. MEIOTIC BEHAVIOR AND REPRODUCTIVE MODE OF EACH CYTOTYPE, American journal of botany, 83(10), 1996, pp. 1309-1322
Citations number
40
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences
Journal title
ISSN journal
0002-9122
Volume
83
Issue
10
Year of publication
1996
Pages
1309 - 1322
Database
ISI
SICI code
0002-9122(1996)83:10<1309:BSOTGI>2.0.ZU;2-H
Abstract
Meiotic behaviors and reproductive modes of Japanese Isoetes were stud ied. The hexaploid (2n = 66) and the octaploid (2n = 88) of I. japonic a consistently formed 33 and 44 bivalents, respectively, at diakinesis and/or metaphase I in both micro- and megaspore mother cells. The tet raploid (2n = 44) of L sinensis formed 22 bivalents and its hexaploid made 33 bivalents in both types of spore mother cells. At diakinesis a nd/or metaphase I of microspore mother cells in I. asiatica with 2n = 22, 11 bivalents were detected. Because behaviors of meiosis in all cy totypes mentioned above were quite regular and plants yielded normal-a ppearing spores, they should reproduce sexually. Aneuploids of I. japo nica with 2n = 87 formed 43 bivalents and one univalent, and L sinensi s with 2n = 65 formed 32 bivalents and one univalent in microspore mot her cells. Meiosis of both cytotypes was almost regular and yielded mi crospores of normal appearance. In the heptaploid (2n = 77) of I. japo nica, a configuration of 22 bivalents and 33 univalents was detected i n micro- and megaspore mother cells, and various irregularities were o bserved throughout the meiotic divisions. Therefore, the genomic formu la 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 r egularly formed bivalents and odd-numbered ones displayed irregulariti es, allopolyploidy should act as a significant speciation mechanism in this genus.