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Molecular Plant Breeding 2011, Vol.2, No.10, 68
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We did not detect any QTLs for glucose and fructose
contents in this study. This may be because the
genetic map used for QTL analyses did not fully cover
all of the wheat genomes; that is, there were few
markers on some chromosomes, and some individual
chromosomes were very short in length (Li et al.,
2007). The genetic complexity of these traits may be
another reason why it was difficult to detect QTLs for
glucose and fructose.
We detected four additive QTLs for sucrose content
(total contribution, 49.30%), and four for maltose
content (total contribution, 79.39%). Thus, sucrose
and maltose content were mainly controlled by
additive QTLs. The maltose content QTL
qMac-2D-1
showed the highest contribution to phenotypic
variation (38.30%). This major QTL showed an increasing
effect coming from Shannong 483. Although there
were some significant correlation coefficients (r),
e.g., between glucose content and fructose content,
between glucose content and raffinose content, and
between raffinose content and fructose content, we did
not detect co-located QTLs on the corresponding
chromosomes.
Water-soluble oligosaccharides contents in grains are
connected with wheat quality traits. As microbial
energy sources, sucrose and maltose affect the
fermentability of wheat by yeasts. In wheat foods, this
can affect quality traits such as the volume,
appearance and taste of Chinese steamed bread, and
the stickiness of noodles (Liu et al., 2001). In previous
studies, QTLs for protein and starch quality traits (Sun
et al., 2008), kernel shape and weight traits (Sun et al.,
2009), and quality traits of Chinese dry noodles (Zhao
et al., 2009) were detected using this population. Moreover,
some were co-located in similar chromosome regions
to those of the QTLs for water-soluble oligosaccharide
contents identified in this study. For example, three
QTLs for Zeleny sedimentation volume, mixing
tolerance index, and final viscosity were mapped to
the
Xwmc432a-Xwmc336c
region on Chromosome 1D
(Sun et al., 2008). This indicated that maltose content
in wheat is connected to protein and starch traits.
Viscosity of the hot pulp and the final viscosity of rice
starch decreased with increasing maltose content;
moreover, different maltose concentrations resulted in
significantly different effects (Xie et al., 2009).
A QTL for sucrose content (
qSuc-3B-1
) was located
around the locus of
Xubc834a
on Chromosome 3B,
near a previously reported test weight QTL (Sun et al.,
2009). Sucrose and starch can be transformed into
each other enzymatically, and starch content has a
significant impact on test weight (Zhang L., 2007).
Therefore, test weight may be indirectly affected by
sucrose content in wheat grains. Furthermore, two
QTLs for stickiness and total score of Chinese dry
noodles were located in the same region as the QTL
for sucrose content on Chromosome 4A (Zhao et al.,
2009). These findings indicate that sucrose content
may influence stickiness and total score of Chinese
dry noodles. In summary, the QTLs for water-soluble
oligosaccharide content and quality traits in wheat
were compared using the same population. These
results can increase our understanding of the effects of
water-soluble oligosaccharides on the quality of wheat
grains and foods made from them.
3 Materials and Methods
3.1 Materials
The RILs population containing 131 lines used for
QTL analysis was derived from ‘Chuan 35050’ × ‘Sha
nnong 483’ (ChSh population, F17 in 2009). Chuan
35050 is a variety with higher sucrose and raffinose
contents that has been planted in the west-southern
winter wheat region of China. Shannong 483 is a
variety with higher maltose content that has been
grown in the Huang-huai winter wheat region.
Shannong 483 was derived from “Ai-Meng-Niu”, a
famous germplasm and backbone parent used
extensively in wheat breeding in China. Shannong 483
was released by Shandong Agricultural University in
1980 and led to the development of more than 16
notable varieties that have been planted over 30
million ha.
The 131 RILs and their parents were planted at Heze,
China, in 2008. The RILs were planted in a
randomized block designed with two replicates. Each
six-row plot was 2 m in length, the rows were spaced
26.7 cm apart, and 70 seeds were grown in each row.
The RILs were harvested and ground into flour in 2009.