233germplasm 0306 is a ROBT consisting of the complete short arm of wheat chromosome
1A and the long arm of a group-1 Ae. peregrina chromosome, T1AS•1 p #1L. The
exact breakpoint in this translocation and the genomic affi nity of the translocated
Ae. peregrina segment re main to be determined. Marais et al. ( 2010a ) used induced
homoeologous recombination to shorten the Ae. peregrina segment in this translo-
cation. Several recombinants T1AS•1AL-1 p #1L with shortened Ae. peregrina seg-
ments with Lr59 were obtai ned (Table 9.2 ). However, molecular marker analysis
suggested that the transferred Ae. peregrina segment is structurally rearranged.
Ae. peregrina is also the source of the root-knot nematode ( Meloidogyne naasi
Franklin) resistance gene Rkn2 ( Rkn - mn1 ) that was transferred to the long arm of
wheat chromosome 3B (Yu et al. 1995 ; Barloy et al. 2000 ).
9.13 Ae. kotschyi
Leaf rust resistance gene Lr54 and stripe rust resistance gene Yr37 were transferred
to wheat from Ae. kotschyi Boiss. (2 n = 4× = 28, U k U k S k S k ) using the centric
breakage- fusion mechanism of univalents at meiosis (Marais et al. 2005 ). Meiotic
pairing indicated that the leaf rust and stripe rust resistance genes in germplasm S14
are located on the ROBT T2DS•2 k #1L. GISH analysis failed to detect the 2 k #1L
chro matin in this translocation and, therefore, the exact breakpoint in this transloca-
tion and its genomic origin remain to be determined.
9.14 Ae. geniculata
Ae. geniculata Roth (2 n = 4× = 28, U g U g M g M g ) is the source of powdery mildew
resistance gene Pm29 , leaf rust resistance gene Lr57 , stripe rust re sist ance gene Yr40
(Kuraparthy et al. 2007b , 2009 ), and stem rust resistance gene Sr53 (Liu et al. 2011b ).
Zeller et al. ( 2002 ) transferred powdery mildew resistance gene Pm29 from a
Poros- Ae. geniculata chromosome addition line (Friebe and Heun 1989 ) to wheat.
Meiotic pairing and molecular marker analyses mapped the Pm29 resistance gene
on wheat chromosome 7D.
Sr53 , conferring resistance to stem rust includ ing race Ug99, is located in the
long arm of the Ae. geniculata chromosome 5M g #1 and is available in wheat in the
form of a spontaneous distal translocation T5DL-5M g #1L•5M g #1S (TA5599) and
an interstitial recombinant chromosome Ti5DS•5DL-5M g #1L-5DL (TA5630). The
interstitial Ae. geniculata segment in Ti5DS•5DL-5M g #1L-5DL corresponds to
approximately 20 % of the 5DL-5M g #1L-5DL arm (Liu et al. 2011b ).
Lr57 and Yr40 are located in the distal reg ion of the short arm of the Ae. genicu-
lata chromosome 5M g #1 and are available in the form of the wheat– Ae. geniculata
recombinant chromosomes T5DL-5M g #1L•5M g #1S (TA5599) and T5DL•5DS-
5M g #1S (TA5601 and TA5602). The breakpoint in the germplasm TA5601 is
9 Wheat–Aegilops Introgressions