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des ) derived amphiploids resistant to PM. Both diploid and tetraploid parental lines
were proposed to carry resistance genes against PM.
The other resistance sources against powdery mildew include Pm12 ( 6B) and
Pm32 (1B) from Ae. speltoides (Jia 1996 ; Hsam et al. 2003 ), Pm29 (7D) from Ae.
geniculata (Zeller et al. 2002 ), Pm34 and Pm35 (5DL) from Ae. tauschii (Miranda
et al. 2006 , 2007 ; Qiu et al. 2006 ), Pm39 from Ae. umbellulata (Zhu et al. 2006 ),
and some undesignated genes from Ae. longissima , Ae. searsii , Ae. umbellulata
(Buloichik et al. 2008 ), Ae. comosa (Bennett 1984 ) and Ae sharonesis (Olivera
et al. 2007 ). From T. monococcum , Pm25 and three temporarily designated genes,
Pm2026, Mlm3033 and Mlm80 , have been introduced in wheat (McIntosh et al.
2010 ).
Molecular Diagnosis for Host Resistance
So far, six genes providing resistance against diseases in wheat have been suc-
cessfully cloned (Liu et al. 2012 ). Diagnostic markers having ability to capture
allelic variation have been developed for a major powdery mildew resistance lo-
cus, Pm3 , and Lr34/Yr18/Pm38 locus providing broad spectrum resistance against
leaf rust, stripe rust and powdery mildew (Tommasini et al. 2006 ; Lagudah et al.
2009 ; Miedner et al. 2012 ). The cloning followed by sequencing of the adjacent un-
translated regions of Pm3 resistance alleles helped in development of seven allele-
specific molecular markers which successfully discriminated allelic variants at the
Pm3 locus (Tommasini et al. 2006 ). In multiple studies, these markers identified
desirable alleles in the US and European wheat cultivars (Peusha et al. 2008 ; Chen
et al. 2009 ; Lillemo et al. 2010 ; Mohler et al. 2011 ). However, their use for identi-
fication of alleles in Chinese wheats is restricted due to the susceptibility of the all
seven alleles in China. The major locus Lr34/Yr18/Pm38 provides durable resis-
tance against many diseases and its usage is encouraged worldwide. The functional
markers developed by Lagudah et al. ( 2009 ) are very simple to apply due to their
easy resolution on agarose gels. This marker provided positive association between
stripe rust and marker data on a wide array of wheat lines developed at CIMMYT
(Wu et al. 2010 ). In another study on Chinese landraces, this marker showed the
presence of Lr34/Yr18/ Pm38 allele in 82.1 % genotypes. However, 25 % of these
genotypes were found susceptible to stripe rust in field (Wu et al. 2010 ). The sus-
ceptibility of landraces with positive Lr34/Yr18/ Pm38 a llele is proposed due to
the presence of inhibitor genes or absence of a functional gene that is essential in
the biosynthetic pathway for the expression of Lr34/Yr18/Pm38. For more than a
decade, the T1BL.1RS translocation has been widely used in global wheat breed-
ing programs. Several agronomic features and resistance to diseases are associated
with this translocation, although its resistances to diseases have been overcome in
many locations. Therefore, it is important to identify the T1BL.1RS translocation
in wheat breeding. Functional markers based on the rye secalin gene on 1RS were
successfully applied in breeding (Liu et al. 2008 ). Another important stripe rust
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