『マツバボタン』に於けるハプロイド植物の出現に就て

日本遺傳學會第五囘大會講演

抄録

1. The gametic chromosome number in the normal Portulaca grandiflora is 9 as already stated by TJEBBES, and the somatic number is 18 (Fig. 18).
2. Two haploids were found among 168 F₂ interspecific-hybrids (Magenta No. 22×Orange No. 35) in 1931, next year one haploid was obtained from 100 F₃ plants. Their parents were normal morphologically and cytologically. These haploids are of about half the stature of P. grandiflora with all organs proportionally smaller.
3. There are 9 univalents in the first maturation division of P. M. C.. The 9 univalents are separate in the possible assortment of 1 and 8, 2 and 7, 3 and 6, 4 and 5 (Tab. 1). Sometimes 1-3 lagging chromosomes are observed (Figs. 2-5).
4. In the homotypic division the halves of dyad chromosomes are distributed with the result that four nuclei are formed all lacking whole set of chromosomes. Accordingly the pollen grains, which are shrunken and empty, have no function (Figs. 6-10, Tab. 2). As far as the present investigation goes, I could not find the assortment of 0 and 9. This assortment is however possible in rare case.
5. Haploid selfed gave no seed at all, and also pollination experiment with the haploid on normal plants was negative, but its reciprocal cross gave 5 seeds. One of them gave a progeny almost wholly of parent type, and has diploid chromosome number of P. grandiflora. This fact apparently indicates that the non-reduction of chromosomes happened in maturation division of E. M. C. of the haploid plant.