INVESTIGADORES
LIA Veronica Viviana
congresos y reuniones científicas
Título:
Association mapping of drought tolerance in sunflower: phenotypic and genetic characterization of INTA inbred lines
Autor/es:
MORENO M.V.; FUSARI C.; NISHINAKAMSU V.; ALVAREZ D.; DI RIENZO J.; HOPP H.E.; HEINZ R.A.; PANIEGO N.; LIA V.V.
Lugar:
Mar del Plata
Reunión:
Congreso; 18th International sunflower conference; 2012
Institución organizadora:
ASAGIR
Resumen:
ABSTRACT
Association
mapping is a powerful tool to identify genes or alleles that contribute to
variation in complex traits using ensembles of unrelated individuals such
as germplasm collections or natural populations. Genome-wide and candidate
gene approaches have been applied in plants but, regardless of the
genotyping strategy, one of the key aspects of the method is obtaining
reliable phenotypic measurements. In candidate gene approaches, both
phenotypic evaluation and the selection of regions for genetic analysis
are major determinants of the power to identify QTL. Tolerance to water
deficit is a highly complex trait for which phenotypic assessment can be
difficult. Different quantitative variables may serve to describe a plant
response to drought and these may vary along different developmental
stages. Here we present a preliminary study aimed to develop an
association mapping platform for drought tolerance in sunflower. The goals
of this work were: a) to assess the suitability of mannitol assays for the
evaluation of drought tolerance during seed germination, and b) to study
nucleotide diversity, linkage disequilibrium and evolutionary patterns of
seven candidate genes previously reported to be involved in the response
to water deficit in sunflower and other species.
Thirty
four sunflower inbred lines were evaluated under two water deficit regimes
(200
mM and 400 mM mannitol) during 11
days. The percentage of germinating seeds was scored at the end of the
experiment and results were analyzed under a logistic regression model. A
set of 7 SSR loci was assayed to infer genetic relationships among the 34
inbred lines studied and seven candidate regions (Hahb4-p,
Hahb4, Suntip, FB, HaL1L, HaDhn1 and CK) were screened for
variation to identify SNP and InDels.
Susceptible
and resistant genotypes were clearly identified in 200 mM mannitol assays,
whereas no such distinction could be achieved under the more stringent
water deficit regime. Analysis of nucleotide diversity revealed an average
SNP frequency of 1/48.3 bp and an average nucleotide diversity (èW) of 0.00501. In agreement with previous
reports, a high level of LD was observed for all the regions (r2=0.88 at 900 bp) except for Suntip, for
which LD decays to r2=0.325 at 207 bp and HaDhn1, for which LD decays to r2=0.249 at 78 bp. No deviations from
neutrality were observed for Suntip and HaDhn1, whereas evidences of
purifying selection were found for Hahb4-p, Hahb4, FB and HaL1L.
The mannitol test proved to be a reliable and potentially useful
method for the screening of drought tolerance in sunflower. The assignment of inbred lines to the susceptible and resistant
categories was highly concordant with previous field trials. All regions evaluated are interesting
candidate genes to be used in association mapping for this trait.
The
results presented here constitute the first steps towards identifying
drought tolerance QTL in sunflower via the association mapping approach. Further efforts are currently being made to
expand the association mapping population, the
number of candidate genes and the phenological stages of the phenotypic
evaluation.