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@PHDTHESIS{Morrissey:58897,
author = {Morrissey, Kate L.},
title = {{B}iological and chemical induction of systemic resistance
in the barley powdery mildew pathosystem},
volume = {73},
school = {Universität Düsseldorf},
type = {Dr. (Univ.)},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {PreJuSER-58897},
isbn = {978-3-89336-475-6},
series = {Schriften des Forschungszentrums Jülich. Reihe Umwelt /
Environment},
pages = {138 S.},
year = {2007},
note = {Record converted from VDB: 12.11.2012; Universität
Düsseldorf, Diss., 2007},
abstract = {Systemic acquired resistance (SAR) provides plants with a
broad spectrum resistance to a variety of phytopathogens
(fungi, bacteria and viruses). In dicotyledons the systemic
resistance can be induced by both biological and chemical
activators. At present it is unclear whether SAR exists in
monocotyledons, however, induced resistance has been well
reported. The barley-powdery mildew interaction
($\textit{Blumeria graminis f.sp. hordei, Bgh}$) was used as
a test system. The effects of various biological
($\textit{Pseudomonas syringae subspecies and Xanthomonas
translucens subspecies}$) and chemical (Bion$^{®}$, INA, SA
and Paraquat) inducers have been analysed. Local
pre-infiltration with some but not all of the bacterial
strains tested led to lower systemic powdery mildew growth.
The bacteria which were able to multiply quickly within
barley were also able to provide protection against fungal
infection. The degree of chemical resistance induced varied
depending on the chemical inducer used, Bion$^{®}$ was the
most effective of those tested. By using a combination of
metabolite and expression analyses a hypothesis was
developed concerning the mechanisms and signalling cascades
involved in the development of the systemic resistance.
Phenylpropanoid biosynthesis does not appear to be involved
in the induced resistance observed in the course of this
study. Little influence was found on the accumulation of
soluble phenolic compounds following the individual local
pre-treatments, whilst alterations were observed after
$\textit{Bgh}$ infection. This was in agreement with the
obtained expression data for PAL and CHS. In contrast three
different pathogenesis-related (PR) proteins displayed
differential regulation. PR-1, PR-2 and PR-3 are commonly
used as markers for SAR in dicotyledons, it was shown here
that Bion$^{®}$ and a $\textit{Pseudomonas syringae}$
subspecies resulted in induced PR-gene expression in barley.
Paraquat led to primed expression, whilst the remaining
bacteria induced local PR transcript accumulation and primed
systemic expression. In some but not all systemic leaves
lipoxygenase, as a marker for JA biosynthesis, was primed or
induced as well as some JA dependent genes. It was
hypothesised that Bion$^{®}$ mediates its systemic effects
through JA signalling, whilst another signal is required for
local responses possibly SA. The bacterial strains tested
appear to involve a variety of signalling mechanisms which
respond with differing speed and intensity. Local triggering
includes reactive oxygen species (ROS) accumulation, at
later time points JA and other signalling molecules induce
defence responses. Paraquat pretreatment sensitised the
barley plants to respond quicker and stronger to subsequent
pathogen attack without having the cost of pre-emptively
producing defence proteins. JA signalling is suggested to be
responsible for local events whilst another signalling
molecule must contribute to the systemic responses, possibly
ROS. Local Paraquat pre-treatment of barley plants had a
massive effect by reducing redox genes in systemic leaves as
shown by differential gene expression. The results pointed
out, that the systemic induced resistance in monocotyledons
involves several different signalling cascades and induces
various defence mechanisms. In some parameters it resembles
SAR of dicotyledons but not in others. Thus the systemic
induced resistance seems to be of higher complexity in
monocotyledons than in dicotyledons and requires further
investigation.},
cin = {ICG-3},
ddc = {333.7},
cid = {I:(DE-Juel1)ICG-3-20090406},
pnm = {Terrestrische Umwelt},
pid = {G:(DE-Juel1)FUEK407},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
url = {https://juser.fz-juelich.de/record/58897},
}