172
and Hsam 1983 ), was placed in translocations 1RS.1AL, 1RS.1BL (1BL arm of
Pavon 76, hence different from that in the original translocation as in cv. Aurora and
Kavkaz) and 1RS.1DL (Lukaszewski 1993 , 1997 ). This did not affect the disease
resistance profi les of the recipient wheat, but affected root biomass: the highest
effect was associated with the 1RS.1AL arm combination, less so with the 1RS.1DL
combination, and the least with the original arm composition 1RS.1BL. It appears
that the combination of loci on 1RS, 1BS, and 1DS produces the best effect as far as
root biomass is involved (Ehdaie et al. 2003 ; Waines and Ehdaie 2007 ).
The historical account of the origins of the 1RS.1BL translocation of wheat
(Zeller and Hsam 1983 ) shows that originally several different sources of the 1R
chromosome were available (however, Schlegel and Korzun ( 1997 ) suggest that in
fact these sources originated from a common stock). Over time only the Aurora/
Kavkaz source spread to breeding programs and commercial wheat the world over.
It seems a question worth asking if this specifi c chromosome arm carries the most
Fig. 7.2 A complete set of centric translocation made from group-1 homoeologues of wheat cv.
Pavon 76 and rye chromosome 1R reconstructed from translocation 1RS.1BL of the Aurora/
Kavkaz origin and 1BS.1RL
A.J. Lukaszewski