Agriculture Reference
In-Depth Information
in China. h e main gene cloning techniques
used include gene express sequence tag
(EST)-based cloning technique, QTL
mapping-based cloning, transposon tagging
technique and dif erentially expressed gene-
based cloning. Genome-wide association
study (GWAS) and high-throughput
sequencing began to be applied in this i eld.
h e expression library transformation
method, which systematically can identify
functional genes in crops, was i rst
developed in China. h ese provide a
methodological base for large-scale cloning
of genes.
in China. Scientists have developed binary
bacterial artii cial chromosomes (BIBAC)
and artii cial chromosomes based on
P1-derived artii cial chromosome (TAC)
vectors to transform multiple genes simul-
taneously. For manipulation of foreign gene
expression, progress has been made on
improving expression ei ciency by using
strong promoter, enhancer and matrix
attachment regions, etc. Marker knockout
technology, timed degradation of target
genes and marker-free transgenic technology
have been under continuous development.
Foreign gene transformation vectors
were constructed using the Cre/lox deletion
system, plant green tissue special promoter
(rbcs) and the R/RS marker knockout
system, which have been applied in
transgenic tobacco and rice.
h rough constructing the expression
vector of double T-DNA insect resistance in
monocotyledons, the i rst marker-free,
double insect-resistant transgenic rice in the
world has been developed. h e updated
transformation system has been con-
structed, which can transform multiple
target genes in minimal constructs and
prevent the selective marker and vector
backbone from entering into receiver
seedlings. h ese improved transgenic tech-
nologies will facilitate the production of GM
plants in China (Wan, 2011).
GENETIC TRANSFORMATION TECHNOLOGY . In
China, genetic transformation technology
for plants includes mainly gene gun-
mediated, agrobacterium-mediated and
pollen tube pathway transformation
methods. h rough integration and optim-
ization, genetic transformation systems
have built up for some crops, such as rice,
cotton, wheat, maize, soybean and poplar.
Due to the establishment of a large-scale
agrobacterium-mediated genetic transform-
ation system in rice, transformation
ei ciency has improved from 40% to 83%,
transformation periods have shortened to
3-4 months and ~5000 genes can be
transformed each year. h rough the inte-
gration of the three transformation
methods, a highly ei cient genetic trans-
formation platform has been developed for
cotton, with 10,000 strains being trans-
formed each year. h e transformation
ei ciency of wheat with the agrobacterium-
mediated method reached 2% and a
transformation technique of the mature
embryo in wheat has been established,
which circumvents the seasonal inl uence in
wheat transgenesis. Transformation with
agrobacterium-mediated methods in the
immature embryo and shoot tip of maize
was developed and transformation ei ciency
can reach about 5%. In soybean, the
cotyledonary node and hypocotyl of
agrobacterium-mediated transformation
methods were used and about 1% transform-
ation ei ciency was achieved.
With the global advancement of high-
ei ciency, multi-gene transformation tech-
niques, new progress has also been achieved
13.2.2 The current R&D status of GM
plants in Japan
Japan is conducting broad research on
agricultural biotechnology. In Japan, the
Ministry of Agriculture, Forestry and
Fisheries (MAFF) is devoting signii cant
resources towards research in genomics and
biotech crop development. An example of
this ef ort can be seen in Japan's contribution
to rice genome sequencing, as well as
genome analysis of other plants such as
soybeans (Yu et al ., 2002; Schmutz et al .,
2010). Initial releases will most likely come
from Japanese public sector research.
Priority traits could include high yield,
disease-resistant rice, drought-tolerant rice
and wheat, nutritionally altered rice and
heavy-metal-accumulating rice.
 
 
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