QTL Analyses in Multiple Populations Employed for the Fine Mapping and Identification of Candidate Genes at
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Date
2007
Authors
Argyris, Jason M.Díaz Bermúdez, Aurora
Ruggieri, Valentin
Jahrmann, Torben
Monforte, Antonio J.
García-Mas, Jordi
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Abstract
Sugar content is the major determinant of both fruit quality and consumer acceptance
in melon (Cucumis melo L), and is a primary target for crop improvement. Nearisogenic
lines (NILs) derived from the intraspecific cross between a “Piel de Sapo”
(PS) type and the exotic cultivar “Songwhan Charmi” (SC), and several populations
generated from the cross of PS × Ames 24294 (“Trigonus”), a wild melon, were
used to identify QTL related to sugar and organic acid composition. Seventy-eight
QTL were detected across several locations and different years, with three important
clusters related to sugar content located on chromosomes 4, 5, and 7. Two PS
× SC NILs (SC5-1 and SC5-2) sharing a common genomic interval of 1.7Mb at
the top of chromosome 5 contained QTL reducing soluble solids content (SSC) and
sucrose content by an average of 29 and 68%, respectively. This cluster collocated
with QTL affecting sugar content identified in other studies in lines developed from the
PS × SC cross and supported the presence of a stable consensus locus involved
in sugar accumulation that we named SUCQSC5.1. QTL reducing soluble solids
and sucrose content identified in the “Trigonus” mapping populations, as well as
QTL identified in previous studies from other ssp. agrestis sources, collocated with
SUCQSC5.1, suggesting that they may be allelic and implying a role in domestication.
In subNILs derived from the PS × SC5-1 cross, SUCQSC5.1 reduced SSC and
sucrose content by an average of 18 and 34%, respectively, and was fine-mapped to
a 56.1 kb interval containing four genes. Expression analysis of the candidate genes
in mature fruit showed differences between the subNILs with PS alleles that were
“high” sugar and SC alleles of “low” sugar phenotypes for MELO3C014519, encoding a putative BEL1-like homeodomain protein. Sequence differences in the gene predicted to
affect protein function were restricted to SC and other ssp. agrestis cultivar groups. These
results provide the basis for further investigation of genes affecting sugar accumulation
in melon.
Description
Keywords
QTL, Melón, Sugars, Sucrose, NILs, Fine-mapping, Candidate genes, BEL1-like
Bibliographic citation
Frontiers in plant science, 8, p. 1-20
AGROVOC subjects
Cucumis meloAzúcar
Análisis de componentes