226
(McIntosh 1991 ). C-banding analysis suggested that the wheat– Ae. speltoides
recombinant chromosome in germplasm C95.24 (TA3945) consisted of the com-
plete sho rt arm of chromosome 2S#1, part of the long arm of 2S#1, and a distal
segment derived from 2AL of wheat, and it was designated as T2AL-2S#1L•2S#1S
(Friebe et al. 1996 ). This study further indicated that germplasm C82.1 (TA3944)
had the recombinant c hromosome T2BL-2S#1S and germplasm C82.2 (TA3947)
had the reco mbinant chromosome T2DL-2S#1L•2S#1S. The translocation line
C82.2 was crossed with Sears’ ph1b mutant and a set of wheat– Ae. speltoides
recombinant lines were produced (Mago et al. 2013 ). By studying these recombi-
nants it was determined that Sr32 was located on the short arm of the 2S#1 chromo-
some and an additional stem rust resistance gene was located on the long arm of this
chromosome.
Kerber and Dyck ( 1990 ) transferred the adult-plant leaf rust resistance gene Lr35
and the seedling stem rust resistanc e gene Sr39 from an Ae. speltoides chromosome,
2S#2, to wheat chromosome 2B using induced homoeologous recombination
(Table 9.2 ). C-banding analysis indicated that the wheat– Ae. speltoides recombi-
nant chromosome T2B-2S#2 consisted of an Ae. speltoides segment from both arms
(Friebe et al. 1996 ). This translocation line was crossed with Sears’ ph1b mutant
and a set of wheat– Ae. speltoides recombinants carrying shortened segments of the
2S#2 chrom osome were produced (Mago et al. 2009 ). By studying these recombi-
nants, Sr39 was located on an interstitial region of the chromosome 2S#2S. Niu
et al. ( 2011 ) also described the production of wheat– Ae. speltoides 2S/2B recombi-
nants involving Sr39 , some of which carried extremely small Ae. speltoides chro-
mosome segments.
A durum wheat– Ae. speltoides chromosome translocation line DAS15 carrying
stem rust resistance gene Sr47 was developed by LR Joppa (USDA-ARS) through
ph1b - induced homoeologous recombination. Although two wheat– Ae. speltoides
translocation chromosomes are present in the line, only one T2BL-2SL•2SS harbors
Sr47. The distal 2BL segment comprised less than 10 % of the long arm (Faris et al.
2008 ). Even though Sr47 is derived from chromosome 2S, its pathotype specifi city,
rust infection type and map location showed that it was different from genes Sr32
and Sr39 , which were also transferred into common wheat from 2S (Faris et al.
2008 ; Klindworth et al. 2012 ). Homoeologous pairing was induced and allosyndetic
recombinants with stem rust resistance were recovered for both arms of 2S
(Klindworth et al. 2012 ). The Ae. speltoides segment in DAS15 carried two stem
rust resistance genes, Sr47 was located on chrom os ome 2BL, while the gene on
chromosome 2BS may be the same as Sr39. Interstitial translocation lines carrying
Sr47 characterized as Ti2BL-2SL-2BL•2BS retained various sized Ae. speltoides
segments in the subtelomeric region of chromosome 2BL.
Dvorak and Knott (Dvorak 1977 ; Dvorak and Knott 1980 , 1990 ) transferred leaf
rust resistance from Ae. speltoides to wheat chromosomes 1B and 6B. The gene pres-
ent in the germplasm 2-9-2 was located on the wheat– Ae. speltoides recombinant
chromosome T6BL•6BS-6S#2S and was designated as Lr36 (McIntosh 1991 ), and
Lr51 present in the germplasm F-7-3 was mapped on an interstitial wheat– Ae. speltoi-
des recombinant chromosome Ti1BS•1BL-1S#1L-1BL by Helguera et al. ( 2005 ).
P. Zhang et al.