BGN 10: Linkage studies of three barley mutants BARLEY GENETICS NEWSLETTER, VOL. 10, II. RESEARCH NOTES
Mortya and R. Takahashi, pp. 47-51

II. 21. Linkage studies of three barley mutants.

I. Moriya and R. Takahashi. The Ohara Institute for Agricultural Biology, Okayama University, Kurashiki, Japan.

(1) Locating a new mutant gene sca for short, crooked awn in OUM 206

The material OUM 206, used in this experiment, is one of the EMS induced mutants obtained from a Japanese cultivar of uzu and naked type, Akashinriki. It is characterized by awns much reduced to only 2 cm in length and markedly crooked outwards at their upper portion. Its stem length is slightly shorter than that of Akashinriki. Since these characters were found to be controlled simultaneously by a single recessive gene, a symbol sca (short, crooked awn) was alloted to the mutant.

Mode of inheritance and linkage was preliminarily studied using crosses of OUM 206 with three tester stocks, Nigrinudum (no albino gene), Goseshikokuhen and E. 321. F2 data from these crosses have revealed that the gene sca is in linkage with uz but independently inherited of n (chromosome 1), v (2), gl3 (4), B (5), o (6), and s (7). A three-point test was performed using another cross, OUM 207 x Russian 82, in order to locate sca on chromosome 3. As apparent in Table 1 and Fig. 1, interrelationships among these three genes, sca, uz and al., involved in this cross have revealed that sca is located rather close to al on the opposite side of uz.

Table 1. F2 and F3 data for linkage of sca for short, crooked awn and al and uz in a cross between OUM 206 and Russian 82.

Fig. 1. A map of three genes on chromosome 3

(2) Establishment of linkage of wst,,j for white stripe on chromosome 3.

In BGN 4, p. 75 were described characteristics of a new white stripe mutant OUM 231 and also presented F2 data for linkage of wst,,j involved in this mutant with two other genes, uz and al, both of which had been known to be on chromosome 3. After a few years, F2 and F3 tests were repeated using the same cross, OUM 231 x Russian 82 in order to obtain more accurate linkage data about this gene. A summarized result is given in Table 2. Weighted average p values in per cent, estimated from the recombination values obtained from F2 and F3 segregations are presented also in this table. Fig. 2 showing arrangement of three genes, wst,,j, uz and al, is also given.

Table 2. F2 and F3 data for linkage of white stripe (wst,,j) and uz and al in a cross between OUM 231 and Russian 82.

Fig. 2. A map of three genes on chromosome 3.

It is noted here that F2 segregations in two crosses of OUM 231 with Col-orange and L.T. 26 have revealed the gene wst,,j being independently inherited of the following genes on six other chromosomes: n (1), v (2), K (4), trd and B (5), o (6) and s (7).

(3) More data for the linkage of cud for curly dwarf growth in OUM 120.

It has already been reported in BGN 5, p. 57, that the curly dwarf mutant gene cud is linked with s for short-haired rachilla on chromosome 7, but is independent of six marker genes on the other six chromosomes. In order to accurately determine the location of cud on chromosome 7, a cross between this mutant and a tester stock having three markers, fs, s and r, together, was newly prepared and studied interrelationships among these four genes in F2 and F3, generations of this cross. The data obtained is given in Table 3. A map of the four genes was also prepared using the weighted average values of p's and shown in Fig. 3. This apparently indicates that cud locates 14.4% apart from fs for fragile stem on the opposite side of s and r. Presumably cud is very close to nld for narrow leaved dwarf.

Table 3. F2 and F3 data for linkage of cud for curly dwarf and three markers fs, r and s on chromosome 7 in a cross with OUM 120.

Fig 3. A map of four genes on chromosome 7

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