A Database for Triticeae and Avena
II. 19. Segregation and linkage of genes on barley chromosome 3 in
one cross-combination tested by chromosome-doubled monoploids and by F2-data.
Ib Linde-Laursen, Agricultural Research Department, Risø National
Laboratory, DK-4000 Roskilde, Denmark. "R"
A line provided by Bodil Søgaard, Department of Physiology, the
Carlsberg Laboratory, and carrying three normally segregating linked morphological
marker genes, cer-zd67 (eceriferum), uz (semibrachytic),
and cer-zn244 (eceriferum) (Søgaard, 1977), and
one esterase gene, Est-f At (Hvid and Nielsen, 1977), on chromosome
3 and the alpha-amylase gene Amy-1 Ke on chromosome 6 (Nielsen and
Frydenberg, 1974) was crossed with the Danish barley variety 'Tystofte
Prentice' that carries genes Est-4 Su and Amy-1 Bi. Chromosome-doubled
monoploids derived from female gametes of the F1-hybrids were produced
by the bulbosum-method (Jensen, 1976) during two production cycles resulting
in about the same number of monoploids. The segregations in the two cycles
did not differ and are pooled.
Segregation of genes cer-zd67, uz, and cer-zn244
was scored among chromosome-doubled monoploids, F2-plants, and additional
F2-plants progeny-tested by an average 20 F3-plants. However, F2-progenies
non-segregating and segregating for the dominant allele of cer-zd67
were recorded together because of difficulties in distinguishing genotypes.
Segregation of isoenzyme genes was recorded in monoploids only. Recombination
frequencies were estimated by the method of maximum likelihood from the
combined F2- and F3-data.
Segregation ratios of genes cer-zd67, uz, and
did not deviate significantly from 3:1 or 1:2:1 in F2 or in F2-progeny
tests (cf. Table 1). The recombination frequencies showed cer-zd67,
uz, and cer-zn244 to be linked in the given order
(Table 2). The genes cer-zd67 and uz were more
closely and uz and cer-zn244 less closely linked
than previously reported (Søgaard, 1977).
Table 1. Segregation of genes cer-zd67,
uz, and cer-zn244 among chromosome-doubled monoploids,
F2-plants, and F2-progenies.
Table 2. Recombination frequencies + S.D.
In the monoploids segregation ratios of each of genes cer-zd67,
uz, and cer-zn244 deviated significantly from
the 1:1-ratios expected. In each case the deviation was caused by a deficiency
of about 50 percent of plants with the recessive genotype (cf. Table 1).
The segregation ratios of the esterase and alpha-amylase genes, respectively,
did not deviate significantly from 1:1, the esterase genes showing a ratio
of 68 (Est-4 At) to 71 (Est-4 Su) among monoploids and the
alpha-amylase genes a ratio of 65 (Amy-1 Ke) to 74 (Amy-1 Bi).
Because of the large deviations from 1:1 ratios of the single gene segregations
of cer-zd67, uz, and cer-zn244,
no estimations of recombination frequencies were carried out in this material.
The isoenzyme genes segregated independently of each other and of the morphological
Fl-material from the same cross-combination was used to produce both
the chromosome-doubled monoploids and the F2-plants. Therefore, the deviating
segregations in the monoploid material with reduced transmission of gametes
with genes cer-zd67, uz, and cer-zn244
may be caused by the bulbosum technique of producing the doubled monoploids
at one or several of the steps involved.
Hvid, S. and G. Nlelsen. 1977. Esterase isoenzyme variants in barley.
Jensen, C. J. 1976. Barley monoploids and doubled monoploids: Techniques
and experience. Barley Genetics III:316-345.
Nielsen, G. and 0. Frydenberg. 1974. Linkage between the loci Amy1 (alpha-amylase),
o (orange lemma) and x (xantha seedling). BGN 4:53-54.
Søgaard, B. 1977. The localization of eceriferum loci in barley.
V. Three point tests of genes on chromosome 1 and 3 in barley. Carlsberg
Res. Commun. 42:67-75.
BGN 10 toc
BGN Main Index