エビスグサ

Morphological, genetical and a s well as cytological studies were carried out on certain progenies of the asynaptic wild senna (Cassia Tora Linne) found in the progeny of the wild senna collected in the open field situated in the neighbourhood of the center of Atomic-bomb Explosion on Aug. 9, 1945, at Nagasaki City. The results obtained are briefly summarized as follows : 1. Thirteen trisomic plants discovered in the progenies of the asynaptic plants in 1952 were easily distinguished from both the normal and the asynaptic ones by the lesser expression of vigours at their seedling stage. Specific characters, such as the smallness of the petals and as the protruding pistils at late flower-bud stage, were noticed in these trisomic plants. The shape, size and colo it of the petals in these trisomic plants were slender, much smaller and fainter, respectively, than those of the original asynaptic plant. From the chromosomal configurations at the reduction division, these trisomic plants could be divided into two groups, that is, the first group, consisting of nine trisomic plants, showed the chromosomal configurations such as 1_111+12_11, 13_11+1_1, 1_111+11_11+2_1 or 12_11+3_1 at diakinesis and at MI. Each plant in the second group, consisting of four other trisomic plants contained, however, asynaptic genes in homozygotic state in addition to an extra chromosome. From the progeny analysis of reciprocal crossings between the normal and the trisomic plants, it was acertained that the trisomic nature could be transmitted in about 3.8 per cent of offspring through pollen-grains and 17 per cent through ovules. 2. In 1951, a highly sterile plant with two extra chromosomes (SL. 31-1) was discovered in the F_3 generation of the crossing between the asynaptic and the normal plants. This plant started to flower about ten days later than the normal one. It could be easily distinguished by the smallness of their petals and the protruding pistils in the young-bud stage. From their chromosomal configurations, such as 2111+1111, at diakinesis and at MI, the plant was determined as a double trisomic form and the author could assume that the plant may have arisen from the mating of (n+α+b)- and (n)-gametes. 3. In 1952, a completely sterile plant with two extra chromesomes occurred among the progeny of a trisomic plant. The plant was smaller in size and less in vigour than the parent trisomic one. From the chromosomal configurations at diakinesis and at MI, such as l_iv+12_11, l_iv+11_11+2_i or 14_ii, it was concluded that the plant was a tetrasomic form, having two extra homologous chromosomes in addition. As stated above, it was duly presumed that the plant may have been induced through the selling of the trisomic form. 4. In 1950, a completely sterile plant was discovered among the progeny of an asynaptic plant. This plant did not differed in its plant height compared with the normal one, but made clear the degeneration of their stamens and showed their malformed pistils in various degrees. Moreover, it started flowering one month later than the normal plant. From the results of the cytological observations the plant was determined as a monosomic one along with asynapsis.