Biology Reference
In-Depth Information
12
10
8
AtPep2
AtPep5
6
4
2
0
PDF 1.2
PR-1
PR proteins
Fig. 2.4
Differences in ability of AtPep2 and AtPep5 in triggering two different PR proteins
in
Arabidopsis thaliana
(Adapted from Huffaker and Ryan
2007
)
fl g22 did not (Gust et al.
2007
). Flg22 triggered the induction of
PR1
and
PDF1.2
genes encoding the pathogenesis-related proteins PR-1 and PR-10, respectively but
did not induce
PAL1
encoding the enzyme phenylalanine ammonia-lyase involved
in biosynthesis of phenolics, lignin, and phytoalexins. In contrast, OGA caused the
upregulation of
PDF1.2
and
PAL1
, but not
PR-1
and elf18 induced all three
PR1
,
PDF1.2
, and
PAL1
genes (Denoux et al.
2008
; Aslam et al.
2009
).
Two HAMPs of
Arabidopsis
,
At
Pep2 and
At
Pep5, behaved differently in induc-
ing two different PR proteins in
A
.
thaliana
. Pep2 induced very high expression of
PDF1.2
, while Pep5 was a poor inducer of
PDF1.2
. In contrast, Pep5 induced very
high expression of
PR-1
, while Pep2 was poor inducer of
PR-1
(Fig.
2.4
; Huffaker
and Ryan
2007
).
The pathogenesis-related protein-1 encoding gene
PR-1
was induced in
Arabidopsis
seedlings that were infi ltrated with the PAMP fl g22 solution.
However, no induction of
PR1
was observed after addition of the HAMP OGs
(Denoux et al.
2008
). The PAMP NIP1 isolated from
Rhynchosporium secalis
induced accumulation of PR-1, PR-5, PR-9, and PR-10 proteins, but could not
induce the pathogen-inducible germin-like protein (
OxOLP
), LOX gene (
LoxA
),
and protease inhibitor gene (
SD10
) (Steiner-Lange et al.
2003
). Harpin (HrpN)
derived from the soft rot pathogen
Erwinia carotovora
subsp.
carotovora
induced
PR-1
and
PDF1.2
genes, while another
E. carotovora
-derived elicitor polygalac-
turonase (PehA) induced only
PDF1.2
(Kariola et al.
2003
). The PAMP PGN
(peptidoglycan) treatment induced camalexin but fl g22 did not (Gust et al.
2007
).
While, the fl g22 derived from
Pseudomonas aeruginosa
does not induce cell
death, fl agellin derived from
P
.
syringae
pv.
tabaci
6605 did induce cell death
(Naito et al.
2008
). These results suggest that different PAMPs/HAMPs may
induce distinctly different defense genes.
Although various PAMPs differ in inducing different defense genes, some
PAMPs may behave similarly in inducing certain defense genes. ZmPep1 regulates
the expression of various defense genes in maize. These include endochitinase,
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