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to be essential for normal development of fungi (Levery et al. 2002). Several fungal
pathogens including several forme speciales of
Fusarium oxysporum
(f. sp.
lycop-
ersici
, f. sp.
melonis
, f. sp.
cucumerinum
, and f. sp.
lactucae
),
Pythium graminic-
ola
,
Glomerella cingulata
, and
Sclerotinia cepivorum
contain cerebroside elicitor
(Umemura et al.
2004
). The cerebroside elicitor induced defense signaling systems
and induced resistance against pathogens (Umemura et al.
2004
). These results
suggest that cerebroside elicitors are general elicitors and considered as PAMPs
(Nakashima et al.
2008
).
2.7.6
NEP1-Like Proteins as PAMPs
A 24-kDa necrosis- and ethylene-inducing protein (Nep1) isolated from culture
fi ltrates of
Fusarium oxysporum
f. sp.
erythroxyli
has been found to trigger both
ethylene production and necrosis in numerous dicotyledonous plants (Bailey
1995
; Bailey et al.
1997
). Nep1 acts as a general elicitor and induces Ca
2+
-
dependent signaling system, changes in K
+
and H
+
channel fl uxes, accumulation
of ROS, production of ethylene, enhanced transcription of
PR
genes and callose
deposition (Jennings et al.
2001
; Fellbrich et al.
2002
; Keates et al.
2003
; Bae
et al.
2006
). Nep1-like proteins (NLPs) have been isolated from other fungal
pathogens including
Verticillium dahliae
(Wang et al.
2004
),
Botrytis elliptica
(Statts et al. 2007),
Botrytis cinerea
(Schouten et al.
2008
; Arenas et al.
2010
) and
Magnaporthe grisea
,
Fusarium graminearum
and
Mycosphaerella graminicola
(Motteram et al.
2009
).
2.8
Oomycete PAMPs
2.8.1
PEP-13 as an Oomycete PAMP
Several different PAMPs have been detected in various oomycete pathogens. A pep-
tide fragment (Pep-13), within an abundant cell wall glycoprotein (GP42) from
Phytophthora sojae
, has been identifi ed as a PAMP in oomycete pathogens (Halim
et al.
2004
). It was found to be necessary and suffi cient for receptor-mediated
defense gene expression and synthesis of antimicrobial phytoalexins in parsley
(Nürnberger et al.
1994
; Hahlbrock et al.
1995
). GB 42 is a Ca
2+
-dependent TGase
(
R -glutaminyl- peptide
:amine-
-glutamyltransferase), which catalyzes an acyl trans-
fer reaction between peptide-bound glutamine residues and primary amines includ-
ing the
γ
-amino group of peptide-bound lysine residues, forms intra- or intermolecular
isopeptide bonds resulting in irreversible protein cross-linking (Brunner et al.
2002
).
The PAMP epitope of GP42 has been identifi ed as a surface exposed 13 amino
ε
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