Agriculture Reference
In-Depth Information
in field grown plant as compared to cultured shoots and roots of
Azadirachta
indica
(Srividya and Devi
1998
). It has also been found that because of the source and the
type of explants lepidine content in
Lepidium sativum
vary considerably (Pande
et al.
2002
). It shows that biosynthetic efficiency of populations varies; therefore
we should select a high yielding variety as a starting material (Tripathi and Tripathi
2003
). The basic prerequisite in all this is a good yield of the compound, and cheap
cost compared to the natural synthesis by the plants.
Elicitation can be used as one of the important strategy in order to get better pro-
ductivity of the bioactive secondary products (Chong et al.
2005
; Smetanska
2008
;
Sharma et al.
2011
; Hussain et al.
2012
) and reducing production costs (Miao et al.
2000
; Zhang et al.
2003
). There are reports where elicitors have increased produc-
tion of isoflavonoid phytoalexins (Smith and Banks
1986
), serquiterpenoid phyto-
alexin (Threlfall and Whitehead
1988
), coumarins (Hamerski et al.
1990
), podo-
phyllotoxin (Muranaka et al.
1992
), azadirachtin (Prakash and Srivastava
2008
),
terpenoids (Gao et al.
2011
), hypericins (hypericin and pseudohypericin) and hyper-
forin (Coste et al.
2011
), capsaicinoid (Gururaj et al.
2012
), tanshinone (Kai et al.
2012
), vascicine (Bhambhani et al.
2012
) and resistance to pathogens (Benhamou
et al.
2001
). Mihai et al. (
2011
) reported that biotic and abiotic elicitors stimulate
biosynthesis and increase of resveratrol in
Vitis vinifera
callus cultures. Ahmed et al.
(
2012
) reported that different concentration fungal extract (
Aspergillus niger
and
Penicillium notatum
), yeast extract and chitosan enhance the synthesis of psoralen
in
Psoralea corylifolia
suspension cultures.
The other side of the elicitation has also been used to elucidate the complex
metabolic pathways (Moreno et al.
1996
), to characterize the interaction between
biotic and abiotic stress responses at a molecular level (Atkinson and Urwin
2012
).
There are also studies which have been published to mark the effects of elicitors on
enzymes of secondary metabolism (Zenk
1991
), important signal molecules that
mediate plant resistance reactions (Gao et al.
2012
; Bux et al.
2012
), oxidative burst
(Davis et al.
1993
) phytoalexin signal transduction (Preisig
1994
) and anion chan-
nels (Zimmermann et al.
1998
). Beside that elicitors can be used to study the chemi-
cal nature and signaling pathways of natural substances discharged by microbes,
herbivores, and plants during pathogenic contamination, herbivory, symbiosis and
allelopathic interactions (El- Samra et al.
2011
; Maffei et al.
2012
).
Elicitors and Elicitation
Earlier the term elicitor was used for molecules, which induced the production of
phytoalexins, but it is now simplified as a compound which promotes various kinds
of plant defense system (Hahn
1996
; Nürnberger
1999
). Further an elicitor may also
be defined as a material which, instigate or advances the biosynthesis of specific
compounds when added in small amount to a living cell system. In this way elicita-
tion can be explained as the stimulated or improved biosynthesis of compounds due
to addition of trace amounts of elicitors (Radman et al
2003
, Angelova et al.
2006
).
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