8th INTERNATIONAL WHEAT CONFERENCE

ying chromosome/-arms 6R, 6RL or 6RS. All tested hybrid grains from crosses of these
WRA lines with rye L2 had abnormal undifferentiated embryos whereas in crosses with
L6 and L7, which carry the wild type allele, 77.8 -93.1 % hybrid seeds showed normal
differentiated embryos. This result allows to make the conclusion that mutant Eml allele
from L2 is dominant whereas the wild type allele is recessive.
The appearance of the novel character, such as wheat-rye hybrid embryo lethality, in
wheat-rye F 1 hybrids might be considered in terms of complementary interaction between
genes of both species and described as “Dobzhansky-Müller” model. According to
this model, the Eml allele of rye complements the corresponding gene(s) of wheat. Negative
interaction between these complementary genes (alleles) causes embryo lethality. In
the simplest case it may be only two ortologous genes – one in rye and another in wheat.
In accordance to this suggestion allele Eml in line L2 complements the corresponding
incompatible homeoallele in wheat, but the wild type allele (lines L6, L7 and others) does
not. Whereas the general part of common wheat have low crossability with rye, we took
the attempt to identify the complementary wheat gene(s) by crossing the set of nullisomic-tetrasomic
CS lines with rye L2. Only two nulli-tetrasomic lines N6AT6B and
N6AT6D produced 66.7 and 71.4 % hybrid seeds with normal differentiated embryos,
respectively. In the other crosses all hybrid seeds contained abnormal embryos. These
results confirmed that chromosome 6A of wheat carries a gene which is complement to
Eml of rye. Following the rules for gene symbolisation the wheat and rye genes involved
in the process of shoot apical meristem elimination in the early stage of the development
of hybrid wheat-rye embryos were designated Eml-A1 and Eml-R1, respectively.
This work was supported by DFG (project no.436 RUS 17/76/05) and RFBR (project
no.06-04-48758a).
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