Studies of Asynapsis in Rye

OME years ago A. MilNTZING and the present writer started an investigation on the cytology of population plants and inbred plants of rye, some of the results of which have already been published (MilNTZING and PRAKKEN, 1941; PRAKKEN and MilNTZING, 1942).Most of the inbred material studied consisted of lines which had been inbred for many years, but some 1 1 -and I 2-families were studied as well.The main results of the investigations on the inbred lines will soon be published and therefore the general characteristics of inbred rye will not be discussed in the present article.In one of these II-families (family 100, 1940; this family as all the other material being isolated from the Swedish variety »Stalrag») an »asynaptic» plant was found, viz. a plant which showed many un ivalents and but few bivalents at the first metaphase in the p. m. c.In order to investigate this case of asynapsis a number of plants in family 100 and their offspring were studied, in the years 1940-1942.with respect to meiosis and pollen fertility.-Almost all fixations were made with diluted chrome-acetic formalin after prefixation with Carnoy.Staining was with gentian violet. II. INHERITANCE.Most though not all of the plants studied arose after self-fertilization.The results of self-fertilization in-rye are, however, often very poor.In addition, extremely severe winters decreased the number of plants.In most plants both meiosis and pollen fertility were studied, in others only the one or the other.For these reasons I shall not discuss in detail the rather fragmentary material.In all, 128 plants from 20 families could be studied.As may be seen from Table 1, the number of asynaptic plants in each of the eight segregating families (from normal mother plants) agrees rather well with a 3 : 1 segregation, suggesting a monofactorial recessive inheritance.With one possible exception, the asynaptic plants III. MEIOSIS IN POLLEN MOTHER CELLS OF ASYNAPTIC PLANTS.1. FIRST PROPHASE.Leptotene and zygotene have not been studied in detail.Distinct pachytene stages were studied in both normal and asynaptic plants.