Rice Genomics and Genetics 2015, Vol.6, No.9, 1-9
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Nandakumar et al. (2004) reported that out of ten,
nine STMS markers were found polymorphic across
the hybrids and produced unique fingerprint for 11
rice hybrids. A set of four markers (RM206, RM216,
RM258 and RM263) differentiated all the hybrids
from each other, which can be used as referral
markers for unambiguous identification and
protection of these hybrids. Hashemi et al. (2009)
reported that molecular markers RM1, RM263 and
RM6344 markers for genetic purity test in hybrids
except the first Iranian rice (IRH1). Pervaiz
et al.
(2010) reported that a total of 142 alleles were
detected at 32 polymorphic SSR loci, while three
loci were monomorphic in 75 Pakistani rice
landraces. A dendrogram based divied the genotypes
into four major clusters, differentiating tall, late
maturing and slender aromatic types from the short,
early and bold non-aromatic ones. Brar et al., (2014)
reported, total of 258 alleles were detected at 48
SSR loci with an average number of 5.14 alleles per
locus. These allelic frequency values quite comparable
to those reported earlier keeping in view the lower
number of rice genotypes used in the study.
NTSYS-pc UPGMA tree cluster analysis showed the
clustering of 14 rice genotypes into two major
distinct groups.
4.2 Transgenic approaches for developing crops
with increased iron and zinc bioavailability
Development of micronutrient (e.g. Fe and Zn) rich
and efficient crops using novel molecular tools has
gained attention now a day. Ye et al. (2000) reported
the engineering of soybean ferritin gene and
β-carotene (vitamin A) biosynthesis pathway in rice.
Among the micronutrients, most of work has been
done to tailor transgenic plants with high iron
content and bioavailability (Jain et al., 2003;
Guerinot 2007; Zhu et al., 2007). Takahashi (2003)
reported the developments of transgenic rice plants
expressing the barley nicotinamine aminotransferase
(
NAAT
) gene, one of the genes of enzymes of MA
biosynthetic pathway, which showed tolerance to
low-Fe availability in calcareous soils. This
phenomenon occurred because transgenic rice plants
secreted higher amounts of MAs characteristic of
strategy II than do non-transgenic rice plants.
Vasconcelos et al. (2003) reported enhanced iron
and zinc accumulation not only in brown grains but
also in polished grains of transgenic rice expressing
the soybean ferritin gene driven by the endosperm-
specific glutelin promoter.
Ishimaru et al. (2009) reported that MIR transcripts
were greatly increased in response to Fe deficiency
in roots and shoot tissue. Growth in the MIR T-DNA
knockout rice mutant (mir) was significantly
impaired compared to wild-type (WT) plants when
grown under Fe-deficient or -sufficient conditions.
Furthermore, mir plants accumulated more than
twice the amount of Fe in shoot and root tissue
compared to WT plants, when grown under either
Fe-sufficient or -deficient conditions and plays a
significant role in Fe homeostasis.
5 Improving the protein content and amino
acid quality
Improvement of nutritive value of crop plants, in
particular the amino acid composition, has been a
major long term goal of plants breeding programs
because animals, including humans, are incapable of
synthesizing 10 of the 20 amino acids needed for
protein synthesis and these “essential” amino acids
must therefore be obtained from the diet. The higher
the quality of a specific protein, the more efficiently
it is utilized and the less is needed to meet protein
requirements. Thus changes in protein content or
amino acid pattern of the resultant protein mix can
have significant effects on the efficiency of protein
utilization to meet nutritional requirements (Bouis et
al., 2003).
To improve the nutritional value of rice, transgenic
rice plants were developed with a lysine-feedback
insensitive maize
dhps
gene under the control of
CaMV 35S and the rice glutelin
GluB-1
promoter
for over-expression and seed-specific expression
(Lee et al.,
2001). The transgenic plants were fertile
and expressed the
dhps
gene abundantly or
specifically in rice seeds. Soybean glycine gene was
successfully transferred into
japonica
rice variety
Kitaake (Laiptan et al., 2005).
Chakarborty et al. (2010) produced transgenic potato
expressing a seed albumin (
AmA1
) gene from
Amaranthus hypochondriacus
. These findings
demonstrate the feasibility of using the
AmA1
gene
in genetic engineering to improve the nutritive value
of other non-seed and grain crops. So, proteins that
are already made in a particular plant can have new
