EST Markers in Evergreen Azalea: Development and Use for Classifications Compared to AFLP, Microsatellite and Morphological Data
Articolo
Data di Pubblicazione:
2007
Abstract:
Starting from a cDNA library made from flowers of the Rhododendron simsii
hybrid ‘Flamenco’ 200 cDNA fragments were randomly selected and sequenced.
Putative functions compared to EMBL accessions were found for 30% of the fragments.
Primers were developed on 87 cDNA fragments and used for PCR amplification
on 6 different azalea cultivars and species. Polyacrylamide gel electrophoresis was
used to separate the fragments and after UV staining the presence of polymorphic
bands was evaluated. In those cases that no polymorphisms could be detected new
primers were developed and the procedure was repeated once. This resulted in 32
polymorphic EST markers. Of them 10 were selected and the application of these EST
markers to study genetic diversity and relationships in and evergreen azalea gene pool
was investigated: 40 species and varieties, ancestors of known cultivars, and 44
cultivars chosen among distinguishable horticultural groups were genotyped using 3
AFLP primer combinations 6 microsatellite loci and 10 ESTs. EST markers revealed a
higher genetic distance detection capacity than AFLPs. Similarity matrices produced
for each marker technique showed weak yet significant correlations. Analysis of
molecular variance showed that most of the genetic diversity was attributable to
differences among cultivars within horticultural groups. EST markers outperformed
AFLP and STMS markers representing Fst values. This indicated a low but significant
differentiation among horticultural groups. Although ESTs and STMSs appear to be
the most appropriate markers for paternity analysis and assessment of narrow genetic
relationships, AFLP remains the best technique for phylogenetic studies. EST markers
could be particularly useful for QTL mapping using a candidate gene approach
because they target expressed genes, and for comparative mapping studies because
they are derived from gene coding regions which are more likely to be conserved
across populations and species.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
cDNA libraries; expressed sequence tag; marker development; marker comparison; Rhododendron spp.
Elenco autori:
DE KEYSER E; SCARIOT V; HANDA T; DE RIEK J
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