II.19. Genetic analyses of EMS-induced mutants in barley.
Takeo Konishi. Ohara Institute for Agricultural Biology, Okayama University, Kurashiki 710, Japan.
1. Glossy sheath mutants (gs)
A) Allelism test
In the previous report (BNL 13:50), a total of 31 glossy sheath mutants kept in the Ohara Institute for Agricultural Biology, Okayama University, were classified into 10 groups after mutual test crosses among them: 15 EMS-induced mutants from a cultivar, "Akashinriki", 3 spontaneous mutants among Japanese varieties, 11 Ethiopean strains mutated spontaneously, and 2 linkage testers.
Here are dealt with the results of a further allelism test made thereafter especially with the marker stocks for gs1 to gs6. The results are shown in Table 1.
Table 1. Allelic relationships among glossy sheath mutants
Twenty-four out of the 31 mutants proved to be allelic to some one of the genes, gs1 to gs6, except gs4. But, the remaining seven mutants were found to be conditioned by a gene different from gs1 to gs6. Four mutants, OUM 22; 24 and 31; and 29 among them were known to have gs7, gs8 and gs9, respectively. For the other three the mutant genes involved could not be determined.
B) Linkage of gs2 on chromosome 3
Linkage of gs2 in OUM 25 was tested using F2 and F3 of the crosses with two linkage testers, (A) Russian 82 and (B) Col-orange. The F2 data obtained from the cross A indicated that gs2 was linked with uz with 37.68% recombination, but independent of al. The data in the cross B revealed that the distances, gs2 - xc and uz - xc, were 40.58% and 10.09%, respectively. It is inferred from this and the result, published by Takahashi and Hayashi (1971), that the arrangement of six genes may be cu2 - gs2 - als - uz - xc - al on chromosome 3 (Figure 1). A plan is in progress to determine the interrelationships among these genes, using the hybrid of OUM 25 with a linkage tester, cu2 - als - Uz.
Figure 1. The suggested arrangement of 6 genes on chromosome 3.
2. Dense spike mutants (l series)
A) Linkage of l 9* on chromosome 6
*Since la has been used already for other mutant (Robertson et al. 1941), l 9 was given for this mutant (T. Tsuchiya).
Among EMS-induced dwarf mutants with dense spikes, 10 mutants were selected randomly and crossed with each other and their original variety, "Akashinriki". One half of these mutants have the same gene, l 9, denoted tentatively. As mutants or segregants with the mutated gene are similar in appearance with extremely dense spikes, they are easily distinguishable from the normal types grown in open field or greenhouse, even at dense planting. Therefore, the character will be a good marker for linkage studies.
OUM 113 which had the l 9 gene was crossed with a series of the trisomics from Tsuchiya, except Pseudo-normal. Table 3 indicates clearly the gene l 9 to be located on chromosome 6 in which have been located only a few marker genes. In order to contribute to the knowledge of linkage group 6, further linkage studies of the genes for dense spike and also a new smooth awn (Konishi, 1971) on chromosome 6 is now in progress.
