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located in the 5DS arm at a fraction length of FL 0.75, whereas in TA5602 it is
located at FL 0.95. Molecular marker data suggested that the size of the Ae. genicu-
lata segment in TA5602 is less than 3.5 % of the 5DS chromosome arm. GISH
failed to detect the terminal Ae. geniculata segment in T5DL•5DS-5M g #1S present
in TA5602, which suggested that this transfer is below the detect ion limit of GISH
and, was therefore designated as a “cryptic” transfer (Kuraparthy et al. 2007b ,
2009 ). However, after careful adjustment of the ratio of probe to blocker, it was
feasible to visualize the Ae. geniculata segment in the telomeric region of chromo-
some 5DS (Fig. 9.1 ) (T Danilova et al., unpublished).
For transfer of Lr57 and Yr40 to wheat, a di somic wheat– Ae. geniculata substi-
tution line DS5M g #1(5D) was crossed with the Chinese Spring Ph I^ stock, and the
F 1 was backcrossed to the wheat cultivar WL711 (Aghaee-Sarbarzeh et al. 2002 ).
The Ph I^ stock promotes homoeologous recombination (Chen et al. 1994 ) and,
Fig. 9.1 Genomic in situ hybridi za tio n (GISH) pattern of wheat– Aegilops geniculata introgression
lines resistant to leaf rust ( Lr57 ), stripe rust ( Yr40 ), and stem rust ( Sr53 ). Ae. geniculata chromatin
is visualized by green FITC fl uorescence and wheat chromosomes were counterstained with PI and
fl uoresce red. The wheat– Ae. geniculata recombinant chromosome in TA5599 ( c ) with Lr57 , Yr40 ,
and Sr53 consists of the distal part of the long arm of 5DL of wheat, the proximal part of the long
arm of 5M g #1L, and the complete short arm of chromosome 5M g #1S (T5DL- 5M g #1L.5M g #1S),
whereas the wheat– Ae. geniculata recombinant chromosome in TA5601 ( b ) and TA5602 ( a ) with
only Lr57 and Yr40 consists of the long arm of 5DL, the proximal part of 5DS and the distal part
derived from 5M g #1S (T5DL•5DS-5M g #1S). The breakpoint in the recombinant chromosome pres-
ent in TA5602 was determined to be at FL 0.95 and assumed to be below the detectability of GISH,
which was the reason why this recombinant chromosome was characterized as cryp tic. However,
careful adjustment of probe and blocking DNA detected the presence of Ae. geniculata chromatin
at the telomere of the short arm of T5DL•5DS-5M g #1S in germplasm TA5602
P. Zhang et al.