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Genomics and Applied Biology
, 2012, Vol.3 No.2 8-21
http://gab.sophiapublisher.com
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Table 2 Plant serine proteinase inhibitors family - MEROPS databases
Serine proteinase inhibitor family
Class
Target protease
Kunitz Family
13
Trypsin, Chymotrypsin, Plasma Kallikrein
SERPIN Family
14
Trypsin, Chymotrypsin, Elastase
Proteinase Inhibitor 1 (PP1) family
113
Chymotrypsin, Elastase, Subtilisin, Trypsin
Ragi Seed trypsin / alpha –amylase inhibitor Family
16
Trypsin, Plasma kallikrein, Factor X11a
Squash Family
17
Trypsin
Bowman Birk Family
112
Trypsin, Chymotrypsin, CathepsinG, Matriptase
Mustard seed trypsin inhibitor family
118
Trypsin, Chymotrypsin
Proteinase inhibitor 2 (PP2) family
120
Trypsin, Chymotrypsin, Elastase, CathepsinG, Pronase, Subtilisin
in response to cut, exogenous application of jasmonic
acid (JA), and protein phosphatase 2A (PP2A)
inhibitors and completely inhibited by cycloheximide
(Rakwal et al., 2001). Studies on herbivore-induced
synthesis of glucosinolates, trypsin inhibitors, and
resistance to herbivory in Brassica suggest that
induced levels of trypsin inhibitors vary with
genotypes (Cippolini et al., 2003). Changes in
expression of jasmonic acid (JA)-and salicylic acid
(SA)-dependent defense genes was observed in potato
in response to potato and green peach aphids
infestation (Martinez et al., 2003). Saedler and
Baldwin (2004) demonstrated the potential of VIGS to
manipulate and silence the expression of two
jasmonate-induced genes that mediate the expression
of proteinase inhibitor in Nicotiana attenuata roots and
shoots. Hypothetical model for defense gene
activation involving JA has been proposed which
involves PI genes and jasmonate as critical signals in
dicot’s defense responses (Doares et al., 1995;
Sivasankar et al., 2000). Farmer et al (1992)
hypothesized that lipases may be synthesized or
activated in response to wounding and that linolenic
acid released from membranes may initiate the
intracellular transduction pathway leading to
proteinase inhibitor synthesis. Free linolenic acid
could be converted to jasmonic acid, which may be a
key signaling component that may be very close to the
trans-element(s) that regulate proteinase inhibitor gene
transcription (Figure 1).
Early events of signaling cascade involve changes in
protein phosphorylation pattern, which eventually
regulate various cellular processes in eukaryotes
(Hunter, 1995), including plant defense responses
(Conrath et al., 1997). Phosphorylation of proteins is a
transient process, can be regulated by using protein
phosphatase inhibitors- cantharidin and endothall (Li
et al., 1993; MacKintosh et al., 1994; Millward et al.,
1999). JA is found highly effective in inducing
defense-related and cellular defense proteins,
including PRs (Agrawal et al., 2000; Rakwal et al.,
1999). It is initiated with the interactions of local or
systemic signal molecules (Abscisic acid, systemin,
oligogalacturonic acid, chitosan, electrical, and
hydraulic signals) and putative plasma membrane
receptors (β-glucan-elicitor-binding protein and
systemin-binding protein).
P
-chloromercuribenzene
sulfonic acid (PCMBS) has been shown to inhibit
phloem systemin translocation, and attenuate systemic
induction of protease inhibitor (PI) gene expression.
Wound signal is transduced by an unidentified lipase that
facilitates the release of linolenic acid from membrane
lipids, a process stimulated by ABA. Volicitin, which
originates from oral secretion of insects, also function
like linolenic acid (Alborn, 1997).
Def1
regulates the
conversion of 13(S)- hydroperoxylinolenic acid
(HPOTrE) to 12-oxo- phytodienoic acid (12-oxo-PDA).
Def1
tomato mutant sensitive to insect attack is found
defective in octadecanoid pathway. Diethyldi-
thiocarbamic acid (DIECA) reduces the conversion of
HPOTrE to 13-hydroxylinolenic acid (HOTrE) and
decreases the synthesis of jasmonic acid (Howe, 1996).
Inhibitors of ethylene action (norbornardiene (NBD) and
silver) and salicylic acid prevent jasmonic
acid-stimulated induction of PI expression (Borella, 1996;
O’Donnell, 1996). Okadaic acid, inhibitor of protein
phosphatase1 and 2A, inhibits jasmonate-induced PI
expression; suggest the involvement of these
phosphatases downstream regulatory pathway of
jasmonate. The protein kinase inhibitor, staurosporine,
inhibits PI gene expression induced by ABA, specifically,
but not jasmonate (Dammann, 1997) (Figure 1).