Meiosis in <i>Lilium</i>

Chiasmata and a Spontaneous Translocation Heterozygote in a Natural Population Involving the B-Chromosome of <i>Lilium japonicum</i>

“…B-chromosome: The meiotic configurations of minute B-chromosomes ob served in the present and earlier studies (Mather 1935, Stewart 1943 are very similar to telocentric f1 but clearly different to median f2 denoted by Ogihara (1966) , because they appear to be telocentric at Al and AIL Plants possessing one to four B's from Mt. Iwo-Zen were recorded with frequency of 87 .5per cent; mean number per plant was 1.86.…”

“…Generally speaking, a spontaneous gross change of the chromo somes in the lilies is rarely found. As pointed out by Mather (1935), chromosomal evolution in this genus seems to have progressed by accumulation of minor structural changes rather than by gross changes, and not by the polyploidy. seven were normal, with 12II+O-4B's: mean number of small telocentric B -chromo -somes was 1.86per plant.…”

“…Meiosis in the natural population of L. japonicum is quite regular and mean chiasma frequency appeared higher than 2.80per bivalent observed by Mather (1935). The effects on chiasma frequency and distribution by the presence of B-chromosomes have recently been noticed.…”

“…2. Mather (1935) reported that two B's do not only pair with each other but frequently pair to at least three kinds of ordinary bivalents with a subterminal or lateral chiasma. It is explained that they are homologous to several small pieces located in these ordinary chromosomes and might have originated from the reduplication.…”

“…On the species cytology of this lily, variations in karyotypes and number of B-chromosomes were thoroughly studied among various natural popu lations (Ogihara 1966(Ogihara , 1968. Meiotic behavior, however, has only been observed in one or two plants with B-chromosomes obtained from a nursery (Mather 1935, Stewart 1943). The present study, on the plants raised in nature, comprises meio tic problems such as chiasmata in plants with and without B-chromosomes, spon taneous chromosome aberrations, and interstitial chiasmata in a translocation heterozygote.…”