Publikation
Chutia, R.; Abel, S.; Ziegler, J. Iron and Phosphate Deficiency Regulators
Concertedly Control Coumarin Profiles in Arabidopsis thaliana Roots
During Iron, Phosphate, and Combined Deficiencies Front Plant Sci 10, 113, (2019) DOI: 10.3389/fpls.2019.00113
Plants face varying nutrient conditions, to which
they have to adapt to. Adaptive responses are nutrient-specific and
strategies to ensure supply and homeostasis for one nutrient might be
opposite to another one, as shown for phosphate (Pi) and iron (Fe)
deficiency responses, where many genes are regulated in an opposing
manner. This was also observed on the metabolite levels. Whereas root
and exudate levels of catechol-type coumarins, phenylpropanoid-derived
2-benzopyranones, which facilitate Fe acquisition, are elevated after Fe
deficiency, they are decreased after Pi deficiency. Exposing plants to
combined Pi and Fe deficiency showed that the generation of coumarin
profiles in Arabidopsis thaliana roots by Pi deficiency considerably
depends on the availability of Fe. Similarly, the effect of Fe
deficiency on coumarin profiles is different at low compared to high Pi
availability. These findings suggest a fine-tuning of coumarin profiles,
which depends on Fe and Pi availability. T-DNA insertion lines
exhibiting aberrant expression of genes involved in the regulation of Pi
starvation responses (PHO1, PHR1, bHLH32, PHL1, SPX1) and Fe starvation
responses (BRUTUS, PYE, bHLH104, FIT) were used to analyze the
regulation of the generation of coumarin profiles in Arabidopsis
thaliana roots by Pi, Fe, and combined Pi and Fe deficiency. The
analysis revealed a role of several Fe-deficiency response regulators in
the regulation of Fe and of Pi deficiency-induced coumarin profiles as
well as for Pi deficiency response regulators in the regulation of Pi
and of Fe deficiency-induced coumarin profiles. Additionally, the
regulation of Fe deficiency-induced coumarin profiles by Fe deficiency
response regulators is influenced by Pi availability. Conversely,
regulation of Pi deficiency-induced coumarin profiles by Pi deficiency
response regulators is modified by Fe availability.
Publikation
Ibañez, C.; Poeschl, Y.; Peterson, T.; Bellstädt, J.; Denk, K.; Gogol-Döring, A.; Quint, M.; Delker, C. Ambient temperature and genotype differentially affect developmental and phenotypic plasticity in Arabidopsis thaliana BMC Plant Biol 17, 114, (2017) DOI: 10.1186/s12870-017-1068-5
BackgroundGlobal increase in ambient temperatures
constitute a significant challenge to wild and cultivated plant species.
Forward genetic analyses of individual temperature-responsive traits
have resulted in the identification of several signaling and response
components. However, a comprehensive knowledge about temperature
sensitivity of different developmental stages and the contribution of
natural variation is still scarce and fragmented at best.ResultsHere, we
systematically analyze thermomorphogenesis throughout a complete life
cycle in ten natural Arabidopsis thaliana accessions grown under long
day conditions in four different temperatures ranging from 16 to 28 °C.
We used Q10, GxE, phenotypic divergence and correlation analyses to
assess temperature sensitivity and genotype effects of more than 30
morphometric and developmental traits representing five phenotype
classes. We found that genotype and temperature differentially affected
plant growth and development with variing strengths. Furthermore,
overall correlations among phenotypic temperature responses was
relatively low which seems to be caused by differential capacities for
temperature adaptations of individual
accessions.ConclusionGenotype-specific temperature responses may be
attractive targets for future forward genetic approaches and
accession-specific thermomorphogenesis maps may aid the assessment of
functional relevance of known and novel regulatory components.
Publikation
Hoehenwarter, W.; Mönchgesang, S.; Neumann, S.; Majovsky, P.; Abel, S.; Müller, J. Comparative expression profiling reveals a role of the root apoplast in local phosphate response BMC Plant Biol 16 , 106, (2016) DOI: 10.1186/s12870-016-0790-8
BackgroundPlant adaptation to limited phosphate availability
comprises a wide range of responses to conserve and remobilize internal
phosphate sources and to enhance phosphate acquisition. Vigorous
restructuring of root system architecture provides a developmental
strategy for topsoil exploration and phosphate scavenging. Changes in
external phosphate availability are locally sensed at root tips and
adjust root growth by modulating cell expansion and cell division. The
functionally interacting Arabidopsis genes, LOW PHOSPHATE RESPONSE 1 and
2 (LPR1/LPR2) and PHOSPHATE DEFICIENCY RESPONSE 2 (PDR2), are key
components of root phosphate sensing. We recently demonstrated that the
LOW PHOSPHATE RESPONSE 1 - PHOSPHATE DEFICIENCY RESPONSE 2 (LPR1-PDR2)
module mediates apoplastic deposition of ferric iron (Fe3+) in the
growing root tip during phosphate limitation. Iron deposition coincides
with sites of reactive oxygen species generation and triggers cell wall
thickening and callose accumulation, which interfere with cell-to-cell
communication and inhibit root growth.ResultsWe took advantage of
the opposite phosphate-conditional root phenotype of the phosphate
deficiency response 2 mutant (hypersensitive) and low phosphate response
1 and 2 double mutant (insensitive) to investigate the phosphate
dependent regulation of gene and protein expression in roots using
genome-wide transcriptome and proteome analysis. We observed an
overrepresentation of genes and proteins that are involved in the
regulation of iron homeostasis, cell wall remodeling and reactive oxygen
species formation, and we highlight a number of candidate genes with a
potential function in root adaptation to limited phosphate availability.
Our experiments reveal that FERRIC REDUCTASE DEFECTIVE 3 mediated,
apoplastic iron redistribution, but not intracellular iron uptake and
iron storage, triggers phosphate-dependent root growth modulation. We
further highlight expressional changes of several cell wall-modifying
enzymes and provide evidence for adjustment of the pectin network at
sites of iron accumulation in the root.ConclusionOur study
reveals new aspects of the elaborate interplay between phosphate
starvation responses and changes in iron homeostasis. The results
emphasize the importance of apoplastic iron redistribution to mediate
phosphate-dependent root growth adjustment and suggest an important role
for citrate in phosphate-dependent apoplastic iron transport. We
further demonstrate that root growth modulation correlates with an
altered expression of cell wall modifying enzymes and changes in the
pectin network of the phosphate-deprived root tip, supporting the
hypothesis that pectins are involved in iron binding and/or phosphate
mobilization.
Publikation
Janitza, P.; Ullrich, K. K.; Quint, M. Toward a comprehensive phylogenetic reconstruction
of the evolutionary history of mitogen-activated protein kinases in the
plant kingdom Front Plant Sci 3, 271, (2012) DOI: 10.3389/fpls.2012.00271
The mitogen-activated protein kinase (MAPK)
pathway is a three-tier signaling cascade that transmits cellular
information from the plasma membrane to the cytoplasm where it triggers
downstream responses. The MAPKs represent the last step in this cascade
and are activated when both tyrosine and threonine residues in a
conserved TxY motif are phosphorylated by MAPK kinases, which in turn
are themselves activated by phosphorylation by MAPK kinase kinases. To
understand the molecular evolution of MAPKs in the plant kingdom, we
systematically conducted a Hidden-Markov-Model based screen to identify
MAPKs in 13 completely sequenced plant genomes. In this analysis, we
included green algae, bryophytes, lycophytes, and several mono- and
eudicotyledonous species covering >800 million years of evolution.
The phylogenetic relationships of the 204 identified MAPKs based on
Bayesian inference facilitated the retraction of the sequence of
emergence of the four major clades that are characterized by the
presence of a TDY or TEY-A/TEY-B/TEY-C type kinase activation loop. We
present evidence that after the split of TDY- and TEY-type MAPKs,
initially the TEY-C clade emerged. This was followed by the TEY-B clade
in early land plants until the TEY-A clade finally emerged in flowering
plants. In addition to these well characterized clades, we identified
another highly conserved clade of 45 MAPK-likes, members of which were
previously described as Mak-homologous kinases. In agreement with their
essential functions, molecular population genetic analysis of MAPK genes
in Arabidopsis thaliana accessions reveal that purifying selection
drove the evolution of the MAPK family, implying strong functional
constraints on MAPK genes. Closely related MAPKs most likely
subfunctionalized, a process in which differential transcriptional
regulation of duplicates may be involved.
Publikation
Fellenberg, C.; Ziegler, J.; Handrick, V.; Vogt, T. Polyamine homeostasis in wild type and phenolamide deficient Arabidopsis thaliana stamens Front Plant Sci 3, 180, (2012) DOI: 10.3389/fpls.2012.00180
Polyamines (PAs) like putrescine, spermidine, and spermine are ubiquitous polycationic molecules that occur in all living cells and have a role in a wide variety of biological processes. High amounts of spermidine conjugated to hydroxycinnamic acids are detected in the tryphine of Arabidopsis thaliana pollen grains. Tapetum localized spermidine hydroxycinnamic acid transferase (SHT) is essential for the biosynthesis of these anther specific tris-conjugated spermidine derivatives. Sht knockout lines show a strong reduction of hydroxycinnamic acid amides (HCAAs). The effect of HCAA-deficient anthers on the level of free PAs was measured by a new sensitive and reproducible method using 9-fluorenylmethyl chloroformate (FMOC) and fluorescence detection by HPLC. PA concentrations can be accurately determined even when very limited amounts of plant material, as in the case of A. thaliana stamens, are available. Analysis of free PAs in wild type stamens compared to sht deficient mutants and transcript levels of key PA biosynthetic genes revealed a highly controlled regulation of PA homeostasis in A. thaliana anthers.
Publikation
Stenzel, I.; Ischebeck, T.; Quint, M.; Heilmann, I. Variable regions of PI4P 5-kinases direct PtdIns(4,5)P2 toward alternative regulatory functions in tobacco pollen tubes Front Plant Sci 2, 114, (2012) DOI: 10.3389/fpls.2011.00114
The apical plasma membrane of pollen tubes contains different PI4P 5-kinases that all produce phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2] but exert distinct cellular effects. In the present example, overexpression of Arabidopsis AtPIP5K5 or tobacco NtPIP5K6-1 caused growth defects previously attributed to increased pectin secretion. In contrast, overexpression of Arabidopsis AtPIP5K2 caused apical tip swelling implicated in altering actin fine structure in the pollen tube apex. AtPIP5K5, NtPIP5K6-1, and AtPIP5K2 share identical domain structures. Domains required for correct membrane association of the enzymes were identified by systematic deletion of N-terminal domains and subsequent expression of fluorescence-tagged enzyme truncations in tobacco pollen tubes. A variable linker region (Lin) contained in all PI4P 5-kinase isoforms of subfamily B, but not conserved in sequence, was recognized to be necessary for correct subcellular localization of AtPIP5K5, NtPIP5K6-1, and AtPIP5K2. Deletion of N-terminal domains including the Lin domain did not impair catalytic activity of recombinant AtPIP5K5, NtPIP5K6-1, or AtPIP5K2 in vitro; however, the presence of the Lin domain was necessary for in vivo effects on pollen tube growth upon overexpression of truncated enzymes. Overexpression of catalytically inactive variants of AtPIP5K5, NtPIP5K6-1, or AtPIP5K2 did not influence pollen tube growth, indicating that PtdIns(4,5)P2 production rather than structural properties of PI4P 5-kinases was relevant for the manifestation of growth phenotypes. When Lin domains were swapped between NtPIP5K6-1 and AtPIP5K2 and the chimeric enzymes overexpressed in pollen tubes, the chimeras reciprocally gained the capabilities to invoke tip swelling or secretion phenotypes, respectively. The data indicate that the Lin domain directed the enzymes into different regulatory contexts, possibly contributing to channeling of PtdIns(4,5)P2 at the interface of secretion and actin cytoskeleton.
Bücher und Buchkapitel
Stumpe, M.; Stenzel, I.; Weichert, H.; Hause, B.; Feussner, I. The lipoxygenase pathway in mycorrhizal roots of <span>Medicago truncatula</span> (Murata, N., Yamada, M., Nishida, I., Okuyama, H., Sekijar, J., Hajme, W.). Kluwer Academic Publishers, Dordrecht 287-290, (2003)
0
Bücher und Buchkapitel
Stenzel, I.; Hause, B.; Feussner, I.; Wasternack, C. Transcriptional activation of jasmonate biosynthesis enzymes is not reflected at protein level (Murata, N., Yamada, M., Nishida, I., Okuyama, H., Sekijar, J., Hajme, W.). Kluwer Academic Publishers 267-270, (2003)
0
Bücher und Buchkapitel
Weichert, H.; Maucher, H.; Hornung, E.; Wasternack, C.; Feussner, I. Shift in fatty acid and oxylipin pattern of tomato leaves following overexpression of the allene oxide cyclase (Murata, N., Yamada, M., Nishida, I., Okuyama, H., Sekijar, J., Hajme, W.). Kluwer Academic Publishers 275-278, (2003)
0
Bücher und Buchkapitel
Ziegler, J.; Hamberg, M.; Miersch, O. Allene oxide cyclase from corn: Partial purification and characterization (Williams, J.P., Mobashsher, U., Khan, M.U., Lem, N.W.). Kluwer Academic Publishers, Dordrecht 99-101, (1997)
0