II. 20. A further study on linkage of the "dusky" mutant, dsk.
J. Hayashi, I. Moriya and R. Takahashi, Institute for Agricultural and Biological Sciences, Okayama University, Kurashiki 710, Japan.
In 1972 Takahashi et al. reported in BGN 2:75-76 that the dusky mutant, induced from Japanese cultivar, Chikurin Ibaraki 1 by gamma ray irradiation, was controlled by a single recessive gene "dsk" which was linked with s for short-haired rachilla with 21.58% recombination. The main character of this mutant is that about the time of heading the leaf-blade and sheaths begin to be dehydrated and turn to dusky color. Many small dark spots are seen scattered over the surface of these olive-gray colored plant parts. Even after maturity, the heads and stems remain faint green color.
Ten years have passed since then, and only recently a F3 progeny test of a new cross between the mutant "dusky" and a tester stock with the genes nld-fs-s-r was completed. The summarized data are presented in Table 1. The order of these five genes on chromosome 7 are nld-fs-s-dsk-r as shown in Figure 1.
Table 1. Linkage data for five genes, dsk, nld, fs, s and r, on chromosome 7.
