184
equivalent to a single genome of wheat (Lukaszewski, unpublished). Again, as
judged by seed set, the introgressions do not appear to affect fertility; their effect
on bread making quality is as yet unknown.
The two exercises illustrate that chromatin transfers from wheat to rye are fea-
sible and can have benefi cial effects. Many more wheat loci could be trans ferred to
rye for the benefi t of rye breeding. Perhaps the most tempting, and the easiest to
accomplish, is Rht8 , from chromosome 2D as 2D-2R recombinant and c entric
translocation chromosomes are already available (Lukaszewski et al. 2004 and
unpublished data). Interestingly, cursory observations of the behavior of wheat’s
B-genome monosomics in tetraploid rye suggest that wheat–rye chromosome pair-
ing in rye may be much more frequent than in wheat. With the exception of chromo-
some 5B, each of the remaining six chromosomes was observed involved in pairing,
quite often both arms at the same time (Fig. 7.6 ). Perhaps it is the difference in
chromosome pairing control, which in rye appears to favor differentiated chromo-
somes, or perhaps it is the residual effect of the Ph2 locus in wheat, but wheat–rye
translocations are often recovered in tetraploid rye (Lukaszewski, unpublished;
Wiśniewska et al. 2013 ).
References
Alkhimova AG, Heslop-Harrison JS, Schapova AI, Vershinin AV (1999) Rye chromosome vari-
ability in wheat-rye addition and substitution lines. Chromosome Res 7:205–212
An D, Zheng Q, Zhou Y, Ma P, Lu Z, Li L et al (2013) Molecular cytogenetic characterization of
a new wheat–rye 4R chromosome translocation line resistant to powdery mildew. Chromosome
Res 21:419–432
Anugrahwati DR, Shepherd KW, Verlin DC, Zhang P, Mirzaghaderi G, Walker E, Francki MG,
Dundas IS (2008) Isolation of wheat-rye 1RS recombinants that break the linkage between the
stem rust resistance gene SrR and secalins. Genome 51:341–349
Asiedu R, Fisher JM, Driscoll CJ (1990) Resistance to Heterodera av enae in the rye genome of
triticale. Theor Appl Genet 79:331–336
Fig. 7.6 Wheat B-genome chromosomes ( green ) paring with their rye homoeologues in tetraploid
rye. From left to right : 1B, 2B, 3B, 4B, 6B, and 7B
A.J. Lukaszewski