II.6. Two genetic male steriles, msg6 and msg,,bk, assigned to chromosome 6.
R. F. Eslick, Department of Plant and Soil Science, Montana State University, Bozeman, Montana 59715 USA; R. T. Ramage and D. R. Clark, Agriculture Research Service, U. S. Department of Agriculture, Department of Agronomy and Plant Genetics, University of Arizona, Tucson, Arizona 85721 USA.
Over the years we have been assigning genetic male sterile genes to chromosomes and positioning them in the genetic maps. This is to report progress with genes assigned to chromosome 6.
GENETIC MALE STERILE 6, msg6 (Hienes Hanna)
Male sterile 6 was assigned to chromosome 6 using data from translocation heterozygotes, Table 1.
With the observed recombination values one might conclude that msg6 was on chromosome 1, 2, 4, 6, or 7. The lowest recombination values were obtained with translocation breakpoints of T6- translocations. According to Ramage, Burnham, and Hagberg (1961) both T1-6C and T6-7b are broken in the long arm of chromosome 6. The observed data would indicate msg6 to be near the centromere or in the long arm of chromosome 6.
The recombination values reported for T2-4a and T4-5a with msg6 could be attributed to small numbers. No explanation is offered for the relatively low recombination values for Tl-7a and T3-7a with msg6. These crosses should be repeated.
The T67b balanced tertiary trisomic for msg6 msg6 was obtained and has been added to the world collection.
The l.0 + 0.7 percent recombination of orange lemma, oo with msg6 msg6, Table 2, would confirm the position of msg6 msg6 as near the centromere of chromosome 6. Ramage, et al. (1961), Kramer and Blander (1961), and Persson (1969) have indicated that orange lemma, oo, is very near the centromere of chromosome 6.
GENETIC MALE STERILE,, bk ms,, bk (Betzes)
Male sterile bk was assigned to chromosome 6 with the aid of Betzes primary trisomic 6. The following F2 ratio was obtained:
The deficiency in the recessive class is as expected for a trisomic ratio.
In an allelism test, msms X Msms, msg6 X msg,,bk, the ratio of fertile to male sterile in F1 was 11:0 indicating the genes to be non-allelic. Genetic male sterile bk has been shown to be non-allelic to msg1, msg16, msg23, and msg24, all in the variety Betzes.
In crosses with orange lemma (oo), msg,,bk recombined more frequently with o than did msg6, Table 2. The observed recombination value for all crosses was 6.3 + 0.6 percent.
GLOSSY LEAF 4, gl4
We had assumed glossy leaf 4 to probably be on chromosome 6 on the basis of the reported recombination of 30.4 + 6.7 percent for gl4 and oo by Walker et al. (1963).
In F2 we ran allelism tests with our source of gl4 (direct from Dr. G. W. R. Walker) and obtained the following results:
These results confirm those previously reported by Haus and Tsuchiya (1972) and Tsuchiya (1973, i.e. gl4 is allelic to gl3 and gl2b is allelic to gl1.
The glossy leaf 4 gene was determined to be independent of the msg,,bk gene, Table 2.
GLOSSY SHEATH 4, gs4
Walker et al. 1963 determined a recombination value of 29.4 + 2.6 percent for gl4 and gs4 and thus placed gs4 on chromosome 6. Since gl4 has been shown to be allelic to gl3 on chromosome 4 this would suggest that gs4 would be on chromosoze 4. In crosses with msg,,bk, gs4 was determined to have a recombination value of 13.2 + 1.9 percent with msg,,bk, and 0.1 + 3.5 percent with o when the msg,,bk to o recombination was estimated as 6.3 + 0.6 percent. Thus the gs4 gene can remain, as assigned, on chromosome 6.
The tentative gene order, based on F2 common cross data only may be given as:
The coupled tester stocks are available from these studies.
ERECTOIDES E, ert-e
On the basis of Persson and Hagberg's (1969) report that ert-e was probably in the centromere region of chromosome 6 crosses were made with ms6 and msg,,bk. The same deficiency of the ert-e ert-e genotypes, as reported by Persson and Hagberg (1969), were noted in these crosses, Table 2. Both crosses showed independence of ert-e and the two male sterile genes. This was also true when recombination was determined-within the doubly dominant F3 class and within the singly dominant F3 class, these representing relatively undisturbed ratios for the ert-e gene.
This confirms the report of Persson (1969) that the ert-e gene is not near the centromere of chromosome 6.
References:
Haus, T. E. and T. Tsuchiya. 1972. Allelic relationships among glossy seedling mutants. BGN 2:79-80.
Kramer, H. H., and B. A. S. Blander. 1961. Orienting linkage maps on the chromosomes of barley. Crop Sci. 1:339-342.
Persson, G. 1969. An attempt to find suitable genetic markers for dense ear loci in barley. I. Hereditas 62:25-96.
Persson, G., and A. Hagberg. 1969. Induced variation in a quantitative character in barley. Morphology and cytogenetics of erectoides mutants. Heriditas 61:115-178.
Ramage, R. T., C. R. Burnham, and A. Hagberg. 1961. A summary of translocation studies in barley. Crop Sci. 1:277-279.
Tsuchiya, T. 1973. Allelic relationship between glossy seedling genes, gl3 and gl4 in barley. BGN 3:66-67.
Walker, G. W. R., J. Dietrich, R. Miller, and K. Kasha. 1963. Recent barley mutants and their linkage II. Genetic Data for further mutants. Can. Jour. Gen. and Cyt., 5:200-219.
