Agriculture Reference
In-Depth Information
first library consisted of a set of 64 introgression lines (or CSSLs)
carrying contiguous chromosomal segments of
Oryza glaberrima
MG12
(acc. IRGC103544) in the genetic background of
Oryza sativa
subsp.
tropical japonica
(cv. Caiapó). Well-distributed SSRmarkers were used
to characterize the introgression events. The average size of the substi-
tuted chromosomal segments in the substitution lines was
The
10 cM and
they covered the whole donor genome, except for small regions on
chromosomes 2 and 4. Strong segregation distortion was found on
chromosome 6, re
∼
c sterility
gene
S
1
(see above). Recently, we undertook a GBS characterization of
this population in collaboration with Yale University (unpubl. data).
This led us to a very dense genotyping with 15,000 SNPs, allowing a
26 kb resolution of recombination breakpoints in each line. The three
other libraries were obtained from hybridization between
tropical
japonica
accession Curinga from Brazil and the wild species
Oryza
ru
ecting the sel
sh action of the interspeci
pogon
,
Oryza glumaepatula
,and
Oryza meridionalis
.Theyare
available upon request from the corresponding author of this chapter.
It isworthnoting that theOMAPproject ledbyDr. RodWing (University
of Arizona, AR) prepared BAC libraries and determined genome
sequences for several of the donor accessions of our introgression lines
(Ammiraju et al. 2010; Liakat et al. 2010).
3. Interspeci
c Bridges.
The genetic model of gamete elimination des-
cribed earlier predicts that interspeci
×
Oryza glaberrima
CSSLs, generally carry the
Oryza glaberrima S
1
g
allele,
making their use in breeding dif
c lines, such as the
Oryza sativa
cult as this allele will almost always be
transmitted to their progeny. To facilitate the use of
Oryza glaberrima
in breeding schemes, we conceived of and developed in collaboration
with IRD the concept of interspeci
c bridges, or iBridges. Basically,
iBridges are derived by marker-assisted selection of homozygous
S
1
s
/
S
1
s
interspeci
cBC
1
F
1
individuals, followed by several steps of sel
ng for
fixation. This results in a much-increased proportion of fertile BC
1
individuals in the
first backcross generation. More importantly, these
lines are
compatible
with
Oryza sativa
, as they do not carry the
S
1
g
allele,
so breeders can use them as regular
Oryza sativa
progenitors. Supported
by the GCP, several combinations of iBridges were produced at CIAT,
AfricaRice, and PhilRice (Philippines) from a selection of crosses in-
volving 25
Oryza glaberrima
and 3
Oryza sativa
accessions.
4. Universal Core Genetic Map.
To facilitate the creation of easily
comparable, low-resolution genetic maps with evenly distributed
markers in rice (
Oryza sativa
L.), a Universal Core Genetic Map
