Euphytica 137: 251–259, 2004.
2004 Kluwer Academic Publishers. Printed in the Netherlands.
Mapping QTLs for kernel oil content in a tropical maize population
, C.L. de Souza Jr.
, A.A.F. Garcia
, A.F. Garcia
, S.T. Sibov
& A.P. de Souza
Centro de Biologia Molecular e Engenharia Gen
etica (CBMEG), Universidade Estadual de Campinas (UNI-
CAMP), Cidade Universit
aria Zeferino Vaz, CP 6010, CEP 13083-970, Campinas-SP, Brazil;
etica, Escola Superior de Agricultura ‘Luiz de Queiroz’ (ESALQ), Universidade de S
ao Paulo (USP), CP 83,
CEP 13400-970, Piracicaba-SP, Brazil; (
author for correspondence: e-mail: firstname.lastname@example.org)
Received 10 June 2003; accepted 22 March 2004
Key words: composite interval mapping, microsatellites, molecular markers, oil content, quantitative trait loci,
tropical maize germplasm, Zea mays L.
Maize cultivars often have low kernel oil content. To increase the oil content, efﬁcient maize breeding programs have
to be developed, which require the knowledge of the inheritance of this trait. Thus, the objective of this research was
to map quantitative trait locus (QTLs) and estimate their effects for kernel oil content in a tropical maize population.
Two maize inbred lines, contrasting for kernel oil content, were used to develop an F
population. Four hundred
and eight F
plants were self-pollinated, and their kernels (F
progenies) were used for kernel oil evaluation. A
genetic map with 75 microsatellites was developed, and the QTLs were mapped using the composite interval map
(CIM); also, estimates of genetic and phenotypic variances, and heritability coefﬁcient were computed. The map
presented 10 linkage groups, spanned 1,438.6 cM in length with an average interval of 19.18 cM between adjacent
markers. The kernel oil content averaged 58.40 g kg
, and the broad-sense heritability was high (h
Thirteen QTLs were mapped, which were distributed into eight chromosomes, and explained 26.64% of the genetic
variation. QTLs in chromosomes 1, 5, and 6 contributed the most for kernel oil content. Nine out of 13 QTLs with
favorable alleles were from the parental inbred with the highest kernel oil content. The average level of dominance
was partial, but gene action of the QTLs ranged from additive to overdominance. Eight out of 13 mapped QTLs
were already reported for temperate maize populations.
Abbreviations: QTL: quantitative trait locus; NMR: nuclear magnetic resonance
Maize (Zea mays L.) kernels have been used as the
main component for domestic animal feed, such as
poultry and swine. Approximately, 36% and 18% of
maize production in the world is used in the elabora-
tion of feed for poultry and swine, respectively (Perry,
1988). Feed prepared with high oil content maize ker-
nels have increased the daily weight gain both in poul-
try and swine (Han et al., 1987; Goss & Kerr, 1992).
Also, for humans, oil from maize kernels presents high
acceptability because of the high unsaturated fatty acid
content, and thus low cholesterol levels are produced
when metabolized (Weber, 1987).
The widespread use of molecular markers to de-
velop genetic maps and to map chromosomal regions
that affect quantitative traits (QTLs) have provided
more insight in the genetic basis of quantitatively in-
herited traits, such as grain yield and their compo-
nents, and other importantly agronomic traits in maize
(Lee, 1995; Khavkin & Coe, 1997; Kraja & Dud-
ley, 2000). Nevertheless, despite the importance of
the oil content in maize kernels, limited information
on QTL mapping for this trait is available. Berke &
Rocheford (1995) mapped 31 QTLs distributed in 11
chromosome regions; Goldman et al. (1994) mapped
25 QTLs distributed in 13 chromosome arms; Alre-
faietal. (1995) mapped QTLs for the different fatty