A Database for Triticeae and Avena
IV.1. Recombination values of four genes on chromosome 1.
R. F. Eslick, E. A. Hockett*, and G. D. Kushnak. Department of Plant
and Soil Science, Montana State University, Bozeman, Montana 59715, U.S.A.
(*Research Geneticist, Plant Science Research Division, ARS, U.S.D.A.).
Over the years we have accumulated recombination ratios in connection
with our breeding programs. Within a given cross we rather consistently
examine four or more families. This is to report progress to date on four
genes, covered vs naked (Nn), fertile vs male sterile (Ms1Oms1O),
full vs 1/2 awn (lk2lk2) and fertile vs male sterile (Ms14ms14).
Pedigrees of crosses reported in tables 2, 3 and 5 are recorded in table
1. R. W. Allard's tables (Hilgardia 24:235-279, 1956) were used to calculate
combined maximum likelihood recombination values utilizing all data.
Table l. Crosses used to determine recombination
Translocation data indicated that ms1O and ms14 loci were
probably in the centromere region of chromosome 1 (R. F. Eslick, Barley
Genetics II:292-297, 1971). From 3 point test data Eslick, et al., (BGN
1:20-22, 1971) showed the gene order to be:
From the data of table 2 the combined recombination value n-ms1O
was calculated to be 7.2% + 0.41%. A homogeneity chi square of 63.880
with 16 degrees of freedom (P < .005) indicates this calculated recombination
value does not fit all observed ratios equally well. Four of 22 families
in the F3 of cross 19 were dropped to obtain 18 homogeneous families for
Table 2. Segregation ratios for crosses involving
covered and naked (Nn) and fertile and male sterile (Ms1Oms1O) on chromosome
The combined recombination value of n-lk2 (table 3) was determined
to be 7.9% + 0.32%. The homogeneity chi-square of 26.483 with 13
degrees of freedom (P.025-P.010) indicated that the recombination value
of 7.9% did not equally apply to all crosses.
Table 3. Segregation ratios for crosses involving
covered and naked (Nn) and full-awn and half-awn (Lk2lk2) on chromosome
The calculated combined recombination value for lk2-ms10
was 14.7% + 0.71%. Homogeneity chi-square for fit to all crosses
was 14.087 with 10 degrees of freedom and p lies between .250 and .100.
Based on the previous results with translocation breakpoints the balanced
male steriles Ms1Oms14/ms1OMs14 were established. With independence
a 9 fertile:7 male sterile ratio should be obtained. With no recombination
in a repulsion cross the expected ratio would be 2:1. It will be noted
that the observed ratio was much nearer 1:1 than 9:7, table 5. Since this
cross provided little information the balanced male sterile x normal fertile
cross was made, Ms1Oms14/ms1OMs14 x Ms10Ms14/Ms1OMs14.
An Lk2Lk2 marker stock was used as the male to eliminate chance
selfing. All F1's from this cross should be fertile and segregate male
steriles if no recombination occurs.
One fertile F2 row and 98 F2 rows segregating male steriles were observed.
The fertile row represents 1/2 of the recombination gametes and thus the
approximate recombination value is 2% + 2%. We are attempting to
recover the ms1Oms14 genes in coupling. This would provide a more
Working recombination percentages for the 4 genes
reported would then be:
Table 4. Segregation ratios for crosses involving
full-awn and half-awn (Lk2lk2) and fertile and male sterile (Ms1Oms1O)
on chromosome 1.
Table 5. Ratios of fertile to male sterile from
the balanced male steriles Ms1Oms14/ms1OMs14
BGN 2 toc
BGN Main Index