CYTOLOGIA
Online ISSN : 1348-7019
Print ISSN : 0011-4545
Cytogenetic Studies in Artificially Raised Interspecific Hybrids of Papaver
VIII. F1 plants of P. bracteata×P. lateritium
Kono Yasui
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1941 Volume 11 Issue 3 Pages 452-463

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Abstract

1. In the F1 plants of P. bracteata×P. lateritium some characters were intermediate between those of the parent plants, but many other characters of the male parent, lateiitium, dominated over those of the female parent, bracteata.
2. The chromosome number of the parent plants was the same, but their sizes were different; the chromosomes in lateritium being generally smaller than those of bracteata. The chromosome number in the F1 plants was 2n=14, just the sum of the gametic chromosome number in the parent plants. The variation in chromosome sizes was greater than either of those of the parent plants.
3. In the meiosis of the F1 plants there were found more than 3 pairs, sometimes 5 pairs of gemini, some of them being unequal and others separating early in the later prophase and behaving like univalents. Many univalents, probably the just mentioned, proceeded earlier than the bivalents into the poles, though their distribution was at random as we see usually in the non-splitting univalents in the 1st meiotic division. Generally 3, sometimes 2, bivalents formed an equatorial plate after many univalents had gone into the poles, and followed them after separation or without separation of partners. Simultaneously when the bivalents were at the equator few univalents were found in the periphery of the equatorial region; the latter has passed into the poles without splitting.
4. The cytokinesis generally occurred after the 1st meiotic division, though often it was incomplete. Several irregularities in the division were observed. Second division was rather regular, but due to the irregular behaviours in the 1st division very few good pollen grains were produced. The F1 plants were highly sterile even when they were back-crossed with healthy pollen grains of the parent plants.
5. Traction fibers were observed clearly especially in the aceto-carmine smear materials. The univalents were connected with one pole by the traction fibers which may play the role of the movement of the univalents without aid from any other additional forces, e.g. the “Stemmkorper”, which was considered by BELAR as a separator of the daughter chromosome groups toward the poles.
The writer's sincere thanks are due to Prof. K. FUJII for his kind advice in the course of this study. The expence of carrying out the present work was partly defrayed out of a grant from the Science Research Fund of the Department of Education to which her thanks are also due.

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© The Japan Mendel Society
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