Rice Genomics and Genetics 2015, Vol.6, No.9, 1-9
7
amino acids introduced into them or genes for new
proteins that have the desired amino acid
composition can be transferred in the target crops.
6 Improving the Vitamin A content
Besides increasing the crop productivity, plant
genetic engineering has been/is being used to create
crops that are tailored to provide better nutrition for
humans and their domestic animals (Bouis et al.,
2003). Micronutrient (iron, zinc, iodine, essential
amino acids, etc) and vitamin (vitamin A) deficiencies
are widely prevalent in Asia and Africa, adversely
affecting the health of more than one-half of the
population.
Vitamin A rich rice, commonly known as ‘Golden
Rice’, contains the genes required to activate the
biochemical pathway leading to
-carotene
. The
intensity of the colour represents the concentration.
It is estimated that in India 50,000 children become
blind every year due to Vitamin A deficiency
(Paarlberg, 2001). So, to provide adequate amounts
of vitamin A to children in developing countries
would save large numbers from night blindness or
actual blindness. Golden rice is an excellent example
of how genetic engineering of plant can be of direct
benefit to the consumer, especially the poor in
developing countries (Potrykus, 2001). Paine et al.
(2005) reported the development of ‘Golden Rice 2’
by introducing maize
psy
in combination with the
Erwinia uredovora
crt1
gene. The research efforts
are now being made by IRRI and various national
institutions to transfer Golden rice 2
psy/crtI
transgene combination from transgenic
japonica
rice
into local rice cultivars via molecular breeding.
Golden rice has been developed to deliver this
nutrient to those populations who need it most
(Potrykus, 2003).
7
Agrobacterium
method for rice transfo-
rmation
Recent advances in plant biotechnology have
provided biologists with the tools to engineer
desirable traits into rice plants with the capabilities
far beyond than those provided by conventional
plant breeding. One important application of genetic
transformation is to transfer one or more useful
genes into an elite cultivar without disturbing its
original genetic background.
Since then, a steady progress has been made towards
the development of efficient protocols for
in vitro
culture and transformation of
japonica
as well as
indica
rice varieties (Roy et al., 2000; Veluthambi et
al., 2003; Bajaj and Mohanty, 2005; Nishimura et al.,
2005; Toki et al., 2006). Rice can now be
transformed efficiently using
Agrobacterium
method.
An array of useful genes has been transferred in
different rice varieties to improve their resistance/
tolerance against insect pests, fungal diseases,
drought/salinity and to improve their nutritional
quality (Jain et al., 2001). Rice is one of the
nutritionally deficient crops especially with respect
to protein content and essential amino acid
composition and recently several efforts have been
made to improve its nutritional quality (Bouis et al.,
2003; Jain et al., 2004). Several factors affecting the
transformation have been reviewed by Jain et al.
(2003) and Yu et al. (2005). Ge et al., (2005) gave a
new efficient tissue culture system suitable for
highly recalcitrant
indica
varieties to improve their
efficiency via
Agrobacterium
mediated transformation.
The transformed lines of Basmati rice cultivar Pusa
Basmati 1 were obtained through
Agrobacterium
transformation (Bhutani et al., 2006; Ignacimuthu et
al., 2006).
In addition, micronutrient element enrichment of
seeds can increase crop yields when sowed to
micronutrient-poor soils, assuring their adoption by
farmers (Welch and Graham, 2004). So, it is
necessary to maintain the agronomic characters
along with enriched micronutrient content of the
crop. The yield/plant was reported to be positively
correlated with 100 grains weight by Sharma and
Sharma (2007). Chakrabarty
et al.
(2010) reported
that yield/plant showed significant positive genotypic
correlation with plant height (0.21), panicles/plant
(0.27), panicle length (0.53), effective grains/panicle
(0.57) and harvest index (0.86). Brar et al. (2015)
also reported significant correlation for 13 of 96
pairs between allele size of molecular markers and
mineral traits, 10 of 144 pairs between molecular
markers and plant traits.
Conclusion
Notably, there was a large variation for mineral
content in rice genotypes suggesting the existence of
genetic potential to increase the concentrations of
