Etude de la portabilité de marqueurs microsatellites issus d'EST de ...

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Bibliography – Simple Sequence Repeats
sequences and genome location across species (Yu et al. 2004; Varshney et al 2005). For
example, Saha et al. (2004) who sequenced the products of one EST-SSR primer pair for
three fescue species, ryegrass, rice and wheat reported that sequences were >85% similar.
Sequence-based comparison of mapped barley EST-SSRs with genetically and/or
physically mapped markers in wheat, rye and rice revealed several markers that showed an
orthologous relationship between examined cereal species (Varshney et al 2005).
Comparison of genome locations of polymorphic EST-SSR markers mapped in both wheat
and rice also confirmed previously known genome relationships with most of the markers
examined (Yu et al. 2004). However, the assessment of colinearity was complicated by the
detection of multiple polymorphic loci in either wheat or rice for 85% of the primer pairs
suggesting sequence divergence or differential gene duplication.
2.7.4 Phylogenetic studies
Genomic SSRs were extensively explored in plant evolutionary studies because of their
high polymorphism level, their co-dominant inheritance, and their reproducibility
(Plaschke et al. 1995; Prasad et al. 2000; Manifesto et al. 2001; Ben Amer et al. 2001;
Leisova and Ovesna 2001; Zhang et al. 2002). However, interspecific phylogenetic studies
in using SSRs were often restricted because of the limited transferability of genomic SSRs
to related species (Lelley et al. 2000) and the high mutation rate. Because being highly
transferable to distantly related species, EST-SSRs are thought to be more suitable for this
purpose. EST-SSRs had been used to investigate their potential in providing useful
information for phylogeny (Rossetto et al. 2002). Three EST-derived microsatellite loci
from Vitis vinifera were amplified and sequenced across eight species of Vitaceae from
four different genera. Phylogenetic analysis of the microsatellite's flanking regions
produced informative results in congruence with previous studies. Based on EST-SSRs
allelic polymorphism among 18 species of Triticum-Aegilops complex using 64 common
wheat EST-SSRs, Bandopadhyay et al. (2004) were able to construct a dendrogram
separating the diploid and tetraploid species.
2.7.5 Marker Assisted Selection (MAS)
Application of MAS has been shown to increase selection efficiency, particularly for traits
with low heritability (Bernardo et al. 2001). It will be increasingly applied to accelerate
selection of traits that are difficult to manage via phenotype, owing to low penetrance
and/or complex inheritance. It will also serve to maintain recessive alleles in backcrossing