GrainGenes

II. 25 New linkage data on chromosome 6 of barley.

T. Konishi, Ohara Institute for Agricultural Biology, Okayama Univ. Kurashiki 710 Japan.

So far, only a few genes have been located on chromosome 6. Recently, however, I have been in success to add to this chromosome three new genes, r,,e for smooth awn, l 9 for dense spike and mt,,f for mottled leaf. The linkage data for the first and second genes were previously reported in BGN 1 and 3, respectively, and that for the last one, mt,,f will be reported in the following. The mutant OUM 22 having this gene was first induced from Akashinriki by EMS treatment. Its main characteristics is conspicuously mottled leaf blades and sheaths appearing from seedling stage to heading time.

In order to determine the gene order of the given genes on this chromosome, OUM and x_n were crossed to a marker stock having three genes, o, r;,e and l 9, and the character segregations in F2 and F3 generations of these two crosses were studied. The results obtained were summarized in Table 1. The recombination value of r,,e with o in the present experiment is estimated to be larger than that of the previous report. This may be attributed to low pentrance of the gene (r,,e) for smooth awn. According to Table 1, it may be possible to conclude that the gene order is o, mt,,f, r,,e, x_n and l 9 on chromosome 6, as is shown in Fig. 1

Table 1. Linkage data for five genes on chromosome 6, o, mt,,f, r,,e, x_n and l 9, obtained in F2 and F3 of two crosses, (A) OUM 22 x o- r,,e - l 9 and (B) x_n x o- r,,e- 1 9.

Fig. 1. A map of five genes on chromsome 6 (Konishi, 1975).

Finally, it is noted that the multiflorous gene (mul2) is not useful as a marker on this chromosome, because of the low expressivity of the gene in the parent and its F2 segregants under both growing conditions in the field and greenhouse at our institute.

BGN 8 toc
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