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equiren~ei~ts (Santbrd, 1993) The original dr~ving power - the real guripowder was
replaced by safer cot~lpressed hel~uni system. A different acceleration system was also
developed based on the spark di,cliarge cllaniber 111 wliicl~ a water droplet was placed
between two electrodes and a h~gh voltage capacitor caused all instant vaporization of the
water, creatlng a shock wave. This sl~ock wave ;~cceltrates DNA coated particles illto the
target plant cells (Christou et al., 1990). Several labs tried their owti honlemade particle
guns (Per1 el a]., 1992). Var~ous dev~ces illid ilitr~ci~cics of b1011stic I>I.OCCSSSS IVC~C
reviewed by Potrykiis ;ind Spa~igenberg (1995). Tlic firat application uf tlic biolistic
process was niadr: by its inventors uallig chlora~~~plienicol acetyl transferase (CAT), a
riiarker gelie (Klein et al, 1987). Later ye;~rs saw [lie two i~~ipo~til~~t j)ublica~iolis ot'
successful transforrriatio~~ of chloroplasts ill Cliln~tiydo~rio~~us and niitochondria in yeilsl
(Jolinston et iil., 1988).
Tills protocol becotiles significant w11eii tlic host cells are not complacent w~th t!lc
methods llhe /Igrobuc~er~iorl-t~iediatcd and direct protoplast transfornialion. Especially
Ayrobuc~o.i~i~i~-li~ediatcd transforniation is, to some cxtent restricted to dicots and it also
requires wounding. Helice, several rzports appear~d using mctliod to obtain transforn~ed
platits in rice (Dntta ct a]., 1990), soybcat~ (Cliristou el al., 1990), niai~c (Fronint el dl.,
1990, Kozicl et al., 1993) 2nd barley (Wan ;ind I.ciiiuux, 1994).
2.1.1.2 Alternative nletl~ods ofgci~etic tra~~sl'orm:itio~~ into plant cells:
Alternative nictl~ods can be div~ded inlo two types: direct physical i~~troduction of
DNA and tr;insnilssion of gellettc tnaterlal by nlodlfied pl;lnt viruses. Viral gene transfer
can also involve physical transmissioli to tlic plant (e.g., nib inoculation). Most iniportant
method of direct introduction of DNA is thc protoplast transformation, ln~t~ally dircct