Poster
Presentation 16:
Reactive Oxygen, NDR1 and NPR1 in
Arabidopsis
Disease Resistance Signaling
Chu Zhang and Allan D. Shapiro
The University of Delaware
Department of Plant and Soil Sciences
Newark, DE 19716
zhangchu@udel.edu
(302) 831-0854
Mutants in the NDR1 gene are compromised in resistance
to multiple
strains of Pseudomonas syringae and Peronospora
parasitica. ndr1
mutants are also affected in specific processes correlated
with disease
resistance in a pathogen strain-specific manner. Previous
work has
suggested that NDR1 acts downstream of the
oxidative burst and upstream
of induced salicylic acid (SA) biosynthesis. This
model would predict
that levels of reactive oxygen production seen early
in the response to
avirulent pathogen should not be affected by the ndr1
mutation. A burst
of hydrogen peroxide production was seen between 2 and
5 hours
post-inoculation with P. syringae pv. tomato DC3000
carrying avrB or
avrRpt2. No significant differences were noted
between ndr1-1 and the
Columbia parental. We have made an ndr1-1/npr1-2 double
mutant. The npr1
mutation was not found to have any affects on the hypersensitive
response
(HR) either in the single or the double mutant.
As such we conclude that
the signaling pathway downstream of npr1 and any feedback
affected by the
npr1 mutation do not contribute to the HR. Analysis
of PR-1, PR-2 and
PR-5 induction in single and double mutants in response
to both virulent
and avirulent P. syringae showed that cell
death and SA make independent
contribution to PR gene induction.
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