Biology Reference
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reported in common bean. The first saturated
bean genetic maps, based on RFLP and RAPD
markers, were developed by Vallejos et al.
(1992), Nodari et al. (1993), and Adam-Blondon
et al. (1994a). The correspondence between
these maps was later established in an inte-
grated linkage map (Freyre et al. 1998;
http://
2009.pdf)
spanning 1,226 cM and includ-
ing more than 550 markers assigned to 11
linkage groups (LG) (named Pv01 to Pv11;
Pedrosa-Harand et al. 2008). A large number
of linkage maps, complete or partial, had been
subsequently developed to study a wide array of
economic traits in common bean. These maps
differ in the parents used, the type of segregating
populations analyzed, and the number and type
of molecular markers included. Establishing
relationships between different genetic maps
is sometimes possible using common anchor
markers. Comparison of genetic maps can help
in the identification of new markers located at
specific relative positions where interesting loci
are mapped.
and the loci controlling the resistance against
six races in the genotypes A252 and Andecha
(Rodriguez-Suarez et al. 2007). However, each
mapping population may lack polymorphisms,
and direct mapping is not always possible. Iden-
tification of robust linkage among an unmapped
gene and markers previously included in a
genetic map also allows the location of new gene
to be determined through indirect mapping. This
method was used to locate the resistance gene
Co-5
on Pv07 (Campa et al. 2005). The
Co-5
gene (previously named
Mexique 3
) conferred
resistance to races gamma and delta 2 and was
originally described in the bean genotype TU
(Fouilloux 1976). SCAR marker SAB3 linked
to
Co-5
(Vallejo and Kelly 2001) was used to
locate the
Co-5
gene on Pv07 using four anchor
loci (BM183, SAS8, Phs, and Sp4/Sp5).
Another application of markers has been the
discovery of gene clusters not only condition-
ing resistance to anthracnose but linked to other
gene clusters conditioning resistance to other
pathogens. The SQ4 marker linked to the
Co-
2
gene on Pv11, for example, appears to be
linked to the
Ur-3/Ur-11
gene cluster condition-
ing resistance to bean rust (Awale et al. 2008).
Markers on Pv01 were used to confirm the pres-
ence of a gene cluster consisting of the
Co-1
4
gene and the
Phg-1
gene that conditions resis-
tance to race 63-23 of the
Pseudocercospora
griseola
pathogen in the Andean genotype AND
277 (Gon¸alves-Vidigal et al. 2011).
Use of Linkage Relationship
Linkage relationship can be used to identify
a gene from the expression of another closely
linked gene. This characteristic is used for the
indirect selection in the development of breed-
ing programs (Collard and Mackill 2008) and can
also be used in genetic analysis to investigate the
inheritance of traits. Implication of a gene in the
expression of a specific trait can be inferred from
the expression of other closely linked genes.
Linkage analysis can be used for the identifi-
cation of genes involved in a specific resistance
reaction through direct or indirect mapping.
Inclusion of a gene controlling the expression
of specific genotype in a genetic map allows its
location to be determined directly. This strategy
was used to map the two genes (
Are
and
RVI
)
involved in the genetic control of resistance to
two anthracnose races (1 and 21) in the resistant
genotype Ms8Eo2 (Adam-Blondon et al. 1994a)
Characterized Resistance Genes
to
C. lindemuthianum
Resistance Specificities Directly or
Indirectly Located in the Genetic Map
Genes conferring specific resistance to differ-
ent races or isolates of
C. lindemuthianum
have
been located on the genetic map of common
bean. Seven main chromosome regions possess-
ing these resistance specificities were identified
on linkage groups Pv01, Pv02, Pv03, Pv04,
Pv07, Pv08, and Pv11. Figure 9.2 shows the
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