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Fig. 10.6 Agrobacterium -mediated gene transfer in plants
(Tzfira and Citovsky 2003 ; Shrawat and Good 2011 ). These include (1) limitation to
carry size base pair (
500 kb), (2) chances of transgene silencing, (3) poor gene
transfer efficiency, and (4) effectiveness against dicot plants. To improve the
efficiency of Agrobacterium -mediated gene transfer, newer modifications in indi-
rect methods, e.g., application of acetosyringone, were applied to increase the host
range (Verma and Mathur 2011 ). Further advances were made while developing
transgenic plants lacking antibiotic marker genes, co-transformation of multiple
T-DNAs, deployment of Ac-/Ds-based mobile genetic elements that helped in the
elimination of marker genes in transgenic plants, and site-specific recombination
strategies (Klee et al. 1987 ; Dafny-Yelin et al. 2008 ; Lacroix et al. 2008 ;
Permiakova et al. 2009 ; Kakkar and Verma 2011 ).
<
10.3.4 Electroporation-Based Transformation in Plants
The transfer of DNA into cells by applying electric field is termed electroporation,
which is one of the common methods for introducing genes into plant cells
(Neumann et al. 1982 ). Gene transfer by electroporation so far has been worked
out for many species, e.g., tobacco, rice, and wheat. The better results have been
obtained for maize plant (Lurquin 1997 ). On applying electric current (pulses), the
transient increase in porosity of the cell membrane allows DNA to easily transfer
and enter into the cytoplasm. After sometime, the pores retain their porosity; as a
result, DNA is unable to escape from the cell (Neumann et al. 1982 ; Chowrira
et al. 1996 ; To et al. 1996 ; Lurquin 1997 ). Although electroporation seems to be an
easy and effective method, its applications are limited to only a few species. In
addition to that, the electric current applied may damage the gene leading to
misleading codons and wrong translational end product (Gaertig et al. 1994 ;
Rakoczy-trojanowska 2002 ; Uchida et al. 2002 ; Wechuck et al. 2002 ).
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