Agriculture Reference
In-Depth Information
Fig. 1.2
Hairy root formation induced by
A. rhizogenes
strain 8196 in potato (
Solanum tuberosum
L.) callus cultures (
a
), regenerated tobacco (
Nicotiana tabacum
L.) plantlets (
b
). (From Arican)
In nature, when plants are suffering from wounds, phenolic compounds are re-
leased from wounded sides and that cause attraction for
A. rhizogenes
. The bacte-
rium moves toward the wounded sites by chemotaxis and infect plant cells. Sub-
sequent infection at wound site followed by transfer of a particular DNA segment
(T-DNA) from the root-inducing (Ri) plasmid (pRi) of the bacteria (Kumar et al.
2006
).
A. rhizogenes
-induced roots have the unique property of being able to grow
in vitro
without exogenous plant growth regulators (Lee et al.
2001
; Rao and Rav-
ishankar
2002
). With this unique ability, by the utilization of
A. rhizogenes
strains
in
in vitro
plant organ cultures, broad range difficulties were eliminated and as a
result, fast growing organs with the capable of producing extensive branching and
main metabolites even higher than the mother plant or new metabolites undetected
in the mother plant or in other kinds of
in vitro
cultures were generated (Doran
2002
; Nader et al.
2006
; Bensaddek et al.
2008
).
Over the three decades, hairy roots have been applied in a wide range of funda-
mental studies of plant biochemistry, molecular biology, and physiology, as well as
for agricultural, horticultural, and large-scale tissue culture purposes (Doran
2002
).
In general, hairy root cultures have been used extensively in root nodule research
(Diaz et al.
1989
; Quandt et al.
1993
; Diouf et al.
1995
; Hu and Du
2006
; Hirotaka
and Hiroshi
2003
; Aarrouf et al.
2012
), production of artificial seeds (Uozumi and
Kobayashi
1997
), plant secondary metabolites and proteins (Aarrouf et al.
2012
),
plant breeding and plant improvement, experimental systems to study responses to
chemicals (Downs et al.
1994
; Mugnier
1997
), plant morphology and development
(Bandyopadhyay et al.
2007
; Turgut-Kara and Ari
2008
; Hasancebi et al.
2011
;
Aarrouf et al.
2012
), detoxifing environmental pollutants (Rugh
2001
), validate
and analyze the functions of genes conferring resistance to root specific pathogens
(Remeeus et al.
1998
; Hwang et al.
2000
; Alpizar et al.
2006
; Aarrouf et al.
2012
)
and study interactions with other organisms such as nematodes (Kifle et al.
1999
),
mycorrhizal fungi and root pathogens (Mugnier
1997
; Christey
2001
). Besides
these sights, enhanced rooting in plants helps establishment or surviving transplant
shocks or abiotic stress like drought, salinity and heavy metal stress (Bulgakov,
2008
; Li et al.
2011
).
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