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@PHDTHESIS{Klug:46951,
author = {Klug, Katharina},
title = {{S}ystemic effects of mycorrhization on root and shoot
physiology of $\textit{{L}ycopersicon esculentum}$},
volume = {69},
school = {Universität Düsseldorf},
type = {Dr. (Univ.)},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {PreJuSER-46951},
isbn = {3-89336-463-3},
series = {Schriften des Forschungszentrums Jülich. Reihe Umwelt /
Environment},
pages = {IV, 105 S.},
year = {2006},
note = {Record converted from JUWEL: 18.07.2013; Universität
Düsseldorf, Diss., 2006},
abstract = {In a splitroot system, the influence of mycorrhization of
tomato plants with the vesiculararbuscular mycorrhizal
fungus $\textit{Glomus intraradices}$ on physiology and
shikimate pathway transcription was investigated to
distinguish between local effects in the mycorrhizal roots
and systemic effects in the shoot and in the non-mycorrhizal
part of a half-mycorrhizal root. Mycorrhization caused a
growth depression and reduced concentrations of elemental
carbon and carbohydrates in mycorrhizal and half mycorrhizal
roots compared to controls. The two parts of the half
mycorrhizal root showed the same low carbon concentration,
indicating a systemic effect on carbon availability in the
root and the great sink strength of the fungus. Despite, in
a developed symbiosis the elevated nitrogen concentration in
shoots and roots of mycorrhizal plants, with higher
concentrations in the mycorrhizal part of the half
mycorrhizal roots, indicated a better supply of mycorrhizal
roots and shoots with nutrients, on the cost of nitrogen
supply of the non-mycorrhizal part of the root. Although
increased nitrogen levels could lead to increased amino acid
synthesis, the biosynthesis pathway for the three aromatic
amino acids, the shikimate pathway, was not regulated in
this later stage of the symbiosis. However, elevated
shikimate pathway transcripts in mycorrhizal roots in the
early stage of the symbiosis were demonstrated for the first
time. This indicates an involvement of the shikimate pathway
in early defence responses against the fungus and an
influence of changes in carbon status and sugar metabolism
on the pathway. A more detailed look to the entry enzyme of
the shikimate pathway in plants revealed that one of its two
isoforms (DAHPS2) was upregulated by mycorrhization. This
one was also induced by short-term ozone exposure, whereas
the other was unaffected under the investigated conditions.
Furthermore, an influence of mycorrhization on the shoot
reaction to ozone was found. Dependent on the mycorrhization
rate, an additional treatment with ozone caused additive
DAHPS induction of the second isoform in shoots. VOC
emissions and glutathione concentrations were only elevated
in shoots of non-mycorrhizal plants after ozone exposure,
indicating changes in root-shoot interactions involving
signalling cascades. Neither early jasmonic acid or hexenal
induction nor later methyl-salicylate emissions seem to be
relevant in the regulation of DAHPS in response to ozone.
Moreover, ozone alone did not only induce the shikimate
pathway in shoots, but there was also an isoform specific
induction of DAHPS transcripts in roots after ozone
treatment, what would require a fast transduction of a shoot
signal to the roots. Whether the signalling from shoot to
root after ozone exposure is mediated by the same compounds
as the root to shoot signalling in the mycorrhizal symbiosis
still remains unclear. Furthermore, the different affected
pathways and substances may be influenced by different
signalling cascades, reflecting the various re-programming
in plant metabolism during interactions with belowground
symbionts and aboveground environmental parameters.},
cin = {ICG-III},
ddc = {333.7},
cid = {I:(DE-Juel1)VDB49},
pnm = {Terrestrische Umwelt},
pid = {G:(DE-Juel1)FUEK407},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
url = {https://juser.fz-juelich.de/record/46951},
}