Biology Reference
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Fig. 9.3. (a) Graphical genotype of a chromosome segment substitution line (CSSL) containing a Koshihikari
segment of the short arm of chromosome 3 in the genetic background of Nipponbare. The 12 boxes represent the
12 rice chromosomes, as numbered at the top. Black and white boxes denote regions derived from Koshihikari and
Nipponbare, respectively. Circle indicates an eating quality QTL on the short arm of chromosome 3 detected in
backcross inbred lines of Nipponbare/Koshihikari. Horizontal bars show the positions of 718 DNA markers used
for genotyping. (b) Mean scores evaluated by sensory tests of cooked rice in CSSL, Nipponbare, and Koshihikari.
White and black boxes denote scores in 2007 and 2008, respectively. Error bars indicate standard deviations.
Abbreviations are as follows: GL, glossiness; TA, taste; ST, stickiness; HA, hardness; OE, overall evaluation of
cooked rice by sensory test. (Revised version of figures from Takeuchi et al. 2008)
at low levels in polished grains (Lucca et al.
2006). Varietal differences in grain components
have been investigated by metabolome analysis,
mainly in indica rice cultivars (Kusano et al.
2007; Mochida et al. 2009). In recent years,
transgenic techniques have been used success-
fully in several studies: elevating the Fe con-
tent of rice endosperm by introducing ferritin
genes (Vasconcelos et al. 2003), increasing the
amino acid content of rice endosperm by intro-
ducing tryptophan synthesis genes (Dubouzet
et al. 2007; Saika et al. 2011), and producing
nutritionally valuable amounts of
locally adapted japonica cultivars. Although
these types of nutritionally enhanced rice are
still in the experimental stages, transgenic tech-
niques for rice improvement are certain to have a
major impact on human health in both develop-
ing countries (ingestion of insufficient nutrients)
and advanced countries (enhancement of food
functionality).
Perspectives
There will certainly be future demand for japon-
ica rice cultivars with improved grain quality and
yield, necessitating the use of the latest technolo-
gies for rice improvement. Advances in tech-
nology are currently being seen in two main
areas: application of novel phenotyping tools and
genetic dissection procedures.
-carotene in
the endosperm (Golden Rice) by introducing the
genes encoding carotene desaturase and phy-
toene synthase (Hoa et al. 2003; Paine et al.
2005). These transgenic approaches can enhance
breeding efforts leading to the development of
β
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