Rice(Oryza sativa) is one of the most important cereal crops,
providing staple food for nearly one-half of the global population.
More than 90% of rice is grown and consumed in Asia where
about 55% of the world’s population lives, reflecting the value of
rice in daily human life. Its importance can be estimated by the
fact that the year 2004 was declared as International Year of Rice
by the United Nations Food and Agriculture Organization. In direct
proportion to the predicted rise in the world’s human population,
rice consumption and demand will increase over the next several
1.To improve yield
2.Little land is now available for farming
3.Crops subjected to environmental stress
4.To enhance the nutritional value of food we
1. Agrobacterium- mediated Gene Transfer
• CAT1 intron was inserted into the selectable marker gene for hygromycin
• Several useful traits that uses Ag transformation are: abiotic stress tolerance,
biotic stress tolerance, herbicide tolerance, nutritional enhancement and
Isolate gene that direct cells to
make protein of interest
Attach the gene to the promoter that
works in plant
Insert the promoter-gene and a gene
for selectable marker into plant
2. Particle Bombardment/ Biolistics
• considered genotype independent and less labor intensive.
• associated sometimes with some risk due to arrangement of multiple
copies of transgenes, particularly in the form of inverted repeats and
problem of high copy number of the transgene, unlike Agrobacterium-
• has been used for investigation on promoter, stress tolerance, nutritional
enhancement, gene expression, plant development and grain yield
3. PEG (polyethylene glycol) Mediated transformation
• Rice protoplasts can be transformed with naked DNA by
treatment with PEG in the presence of divalent cations such as
• Toriyama et al. (1988) and Zhang and Wu (1988) were the first to
recover transgenic rice using PEG technology and thus it is the
first technique used in transgenic rice production
• Shimamoto et al. (1989) were the first to recover fertile
transgenic plants using electroporation in japonica rice.
• protoplasts are not easy to work with and regeneration of
fertile plants is problematic.
• a single-cell manipulation supporting robot for high
throughput microinjection of rice protoplasts have been
5. In planta transformation
• To avoid tissue culture and sterile conditions, in planta
transformation method that depends on a needle dipped in
Agrobacterium culture to prick the seed‘s embryonic
portion that subsequently grows into a plant and sets
transgenic seeds were developed. Supartana et al. (2005)
1. Biotic Stress Tolerance
a. Insect resistance-
• By introducing the gene for virus-enhancing factor in rice, the
effectiveness of baculoviral insecticides against feeding armyworm
larvae was enhanced. (Hakuhara et al,,1999)
• Another strategy for insect resistance is
the use of plant proteinase inhibitor.
Earlier, Irie et al. (1996) generated
transgenic rice resistant to insect storage
pests using hydrolase inhibitors.
b. Bacterial Disease Resistance-
• Bacterial blight, caused by Xanthomonas oryzae
pv. Oryzae (Xoo), along with blast and sheath
blight are most important
• The most promising endogenous rice gene for
bacterial blight resistance identified so far is
Xa21 (Song et al., 1995), which conferred
complete protection against bacterial blight.
Cecropins are antibacterial peptides having broad
spectrum bacteriallytic activity against gram
negative and gram positive bacteria, but not
against eukaryotic cells.
c. Fungal Disease Resistance
• Most promising endogenous resistance (R) gene, Pi-ta (cytoplasmic
NBS receptor), is responsible for resistance to fungal diseases.
• Another gene, OSDR8, is involved in thiamine biosynthesis and acts
upstream in defense signal transduction pathway. Pathogenesis-related
(PR) genes have been used widely to address fungal tolerance in plants.
d. Viral Resistance-
• Insect-vectored viral diseases cause considerable damage to the
rice plant and drastically reduce the yield of the plant.
• To generate virus-resistant transgenic rice, japonica rice was
transformed with a hammerhead ribozyme.
• Resistance against this virus has been introduced in rice by
expressing 39 kDa spike protein of RRSV. RHBV is the
causative virus of a major rice viral disease that can cause
significant damage (up to 50% loss) of the total yield.
2. Abiotic Stress Resistance-
• responsible for most of the reduction that differentiates yield potential
from harvestable yield.
• high temperature, chilling, freezing, water deficit (drought and
salinity), high light intensity, flooding, and exposure to ozone and heavy
• Overproduction of various compatible solutes has been tested in
rice, e.g., glycine betaine, trehalose, proline and polyamines, to achieve
significant drought, cold, and salt tolerance.
• Water channel proteins, aquaporins, are members of the major intrinsic
protein family which regulate the passive movement of water across
membranes. Aquaporins might have a possible role in providing drought
tolerance to plants as they affect the root water uptake.
• A promising strategy against salinity stress is the use of Na+
transporters, which transport cytosolic Na+ to vacuole and, thus protect
cellular machinery. Na+/H+ antiporters from Artiplex or E.coli confer
high salt tolerance in transgenic rice (Ohta et al., 2002).
3. Herbicide Tolerance-
• In rice, bar was the first gene tested for herbicide (Basta,
glufosinate) tolerance. Two gene families that play major roles in
conferring tolerance to herbicides are P450 monooxygenase and
• Cytochrome P450 monooxygenase, a drug-metabolizing enzyme
system in plants and animals, has been widely used to address
herbicide tolerance trait in rice.
• transgenic plants showed tolerance to sulfonylurea herbicide
1. Nutritional Enhancement
>> ‗Golden Rice‘ with provitamin A was generated. Later, the entire
pathway for β-carotene biosynthesis was reconstituted by using just
two structural genes, PSY and crt1
>> Human lactoferrin (HLF) is a major iron binding glycoprotein in
breast milk. Transgenic rice accumulating HLF in seed provided a
novel means for nutrient supplement for infants as recombinant
human lactoferrin could maintain the biological activity in transgenic
rice seeds. (Nandi et al., 2002)
2. Alteration of Starch Content
• In vivo modification of starch using genetic engineering
• Wheat puroindoline genes PINA and PINB were
introduced in rice to modify the grain texture.
Transgenic grains were very soft in texture and referred
as ―Soft Rice.‖ (Nakamura et al., 2002)
Rice is a diverse crop that grows in different ecosystems. Current gene
evolution should provide wide scope for the application of biotechnology
across ecosystems and crop barriers. It is desirable to create superior
transgenic rice plants that can grow in compromised environments and
have higher yields with decreasing arable land availability. Gene
pyramiding or multigene engineering using genes involved in various
agronomic traits is a powerful approach to obtain superior rice varieties
(Ashikari and Matsuoka, 2006). Indeed, rice biotechnology gives great
benefit and safety to all people—particularly resource-poor people.
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