Agriculture Reference
In-Depth Information
of egg plants, a
Solanum melongena
L. breeding line, and
S. melongena
L. Black
egg plant (Todaro et al.
2011
). The use of leaf derive callus for the generation of
stably transformed maize plants has been reported (Ahmadabadi et al.
2007
; Chen
et al.
2010
). This method combines both conventional breeding and biotechnologi-
cal techniques. Genetic transformation using
Agrobacterium tumefaciens
mediated
transformation has been reported in mango, an important fruit crop (Krishna and
Singh
2007
; Singh et al.
2011
). A technique for developing transgenics without the
use of any selectable marker gene has been developed in peanut by taking advan-
tage of high and consistent transformation potential of this crop (Bhatnagar et al.
2010
). The technique of genetic engineering especially gene transfer depends upon
plant tissue culture for the foreseeable future (Budzianowska
2009
).
Besides this backcloth, a number of transgenic crops have been developed and a
few are being grown in many parts of the world and these crops are either herbicide-
tolerant or insect resistant.
InsectResistance
For 21st century, the demands of sustainable agriculture were fulfilled by the ge-
netically engineered crop resistance to insect pests that offers the prospective us-
er-friendly environment and consumer friendly method of crop production. These
biotech crops are genetically modified with
Bacillus thuringiensis
(Bt) endotoxins
for insect resistance and the development of Bt crops stands as one of the most out-
standing successes of transgenic plant biotechnology (Table
3.1
). The Bt is a strong
biological insecticide, which comprises of crystal protein endotoxin that is pro-
duced by some stains of soil bacterium
Bacillus thuringiensis
(Goudar et al.
2012
).
The Bt crystal (cry) genes are toxic to lepidopterans (Cohen et al.
2000
), dipterans
(Andrews et al.
1987
) and coleopterans (Herrnstadt et al.
1986
). Bt cry protein is
toxic to insects (BANR
2000
) and non-toxic to humans and animals. The Bt toxin
gene was first discovered by Ishiwaki in 1901, in diseased silkworms and the first
Bt toxin gene was cloned in 1981 (Jain et al.
2007
). In 1986, the field test of trans-
genic tobacco expressing Bt toxin was performed. Moreover, in 1988 the first GM
plant of japonica rice was produced and after that indica rice in 1990 (Ahmad et al.
2012
). Now the biotech crops are grown globally including soybean, maize, cot-
ton, canola, squash, papaya, sugar beet and tomato and the global biotech crop area
derives soybean, corn, cotton and canola (Brookes and Barfoot
2011
). The avail-
able data this time showed that biotech crops like soybean accounted the largest
share (52 %) followed by corn (30 %) and canola (5 %). 16.7 million farmers across
29 countries (10 industrialized and 19 developing countries) planted 160 million
hectares of biotech crops in 2011 and 90 % were small and resource poor farmers in
developing countries (James
2010
; Ahmad et al.
2012
). However the combination
of transgenic expression and improved protein stability has resulted even death of
the Bt-resistant insects (Chougule and Bonning
2012
; Kota et al.
1999
). But now
a days other insecticidal proteins like lectins, antibodies, protease inhibitors, wasp
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