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
Zayneb, C.; Bassem, K.; Zeineb, K.; Grubb, C. D.; Noureddine, D.; Hafedh, M.; Amine, E. Physiological responses of fenugreek seedlings and plants treated with cadmium Environ Sci Pollut Res 22, 10679-10689, (2015) DOI: 10.1007/s11356-015-4270-8
The bioaccumulation efficiency of cadmium (Cd)
by fenugreek (Trigonella foenum-graecum) was examined using different
concentrations of CdCl2. The germination rate was similar to control
except at 10 mM Cd. However, early seedling growth was quite sensitive
to the metal from the lowest Cd level. Accordingly, amylase activity was
reduced substantially on treatment of seeds with 0.5, 1, and 10 mM Cd.
Cadmium also affected various other plant growth parameters. Its
accumulation was markedly lower in shoots as compared to roots, reducing
root biomass by almost 50 %. Plants treated with 1 and 5 mM Cd
presented chlorosis due to a significant reduction in chlorophyll b
especially. Furthermore, at Cd concentrations greater than 0.1 mM,
plants showed several signs of oxidative stress; an enhancement in root
hydrogen peroxide (H2O2) level and in shoot malondialdehyde (MDA)
content was observed. Conversely, antioxidant enzyme activities
(superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase
(CAT)) increased in various plant parts. Likewise, total phenolic and
flavonoid contents reached their highest values in the 0.5 mM Cd
treatment, consistent with their roles in quenching low concentrations
of reactive oxygen species (ROS). Consequently, maintaining oxidant and
antioxidant balance may permit fenugreek to hyperaccumulate Cd and allow
it to be employed in extremely Cd polluted soils for detoxification
purposes.
Publikation
Delker, C.; Sonntag, L.; Geo, V. J.; Janitza, P.; Ibañez, C.; Ziermann, H.; Peterson, T.; Denk, K.; Mull, S.; Ziegler, J.; Davis, S. J.; Schneeberger, K.; Quint, M. The DET1-COP1-HY5 Pathway Constitutes a Multipurpose Signaling Module Regulating Plant Photomorphogenesis and Thermomorphogenesis Cell Rep 9, 1983–1989, (2014) DOI: 10.1016/j.celrep.2014.11.043
Developmental plasticity enables plants to respond to elevated ambient temperatures by adapting their shoot architecture. On the cellular level, the basic-helix-loop-helix (bHLH) transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4) coordinates this response by activating hormonal modules that in turn regulate growth. In addition to an unknown temperature-sensing mechanism, it is currently not understood how temperature regulates PIF4 activity. Using a forward genetic approach in Arabidopsis thaliana, we present extensive genetic evidence demonstrating that the DE-ETIOLATED 1 (DET1)-CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1)-ELONGATED HYPOCOTYL 5 (HY5)-dependent photomorphogenesis pathway transcriptionally regulates PIF4 to coordinate seedling growth in response to elevated temperature. Our findings demonstrate that two of the most prevalent environmental cues, light and temperature, share a much larger set of signaling components than previously assumed. Similar to the toolbox concept in animal embryonic patterning, multipurpose signaling modules might have evolved in plants to translate various environmental stimuli into adaptational growth processes
Publikation
Costa, C. T.; Strieder, M. L.; Abel, S.; Delatorre, C. A. Phosphorus and nitrogen interaction: loss of QC identity in response to P or N limitation is antecipated in pdr23 mutant Braz J Plant Physiol 23, 219-229, (2011) DOI: 10.1590/S1677-04202011000300006
Changes in root architecture are an important
adaptive strategy used by plants in response to limited nutrient
availability to increase the odds of acquiring them. The quiescent
center (QC) plays an important role by altering the meristem activity
causing differentiation and therefore, inducing a determinate growth
program. The arabidopsis mutant pdr23 presents primary short root in the
presence of nitrate and is inefficient in the use of nucleic acids as a
source of phosphorus. In this study the effect of the pdr23 mutation on
the QC maintenance under low phosphorus (P) and/or nitrogen is
evaluated. QC identity is maintained in wild-type in the absence of
nitrate and/or phosphate if nucleic acids can be used as an alternative
source of these nutrients, but not in pdr23. The mutant is not able to
use nucleic acids efficiently for substitute Pi, determinate growth is
observed, similar to wild-type in the total absence of P. In the absence
of N pdr23 loses the expression of QC identity marker earlier than
wild-type, indicating that not only the response to P is altered, but
also to N. The data suggest that the mutation affects a gene involved
either in the crosstalk between these nutrients or in a pathway shared
by both nutrients limitation response. Moreover loss of QC identity is
also observed in wild-type in the absence of N at longer limitation.
Less drastic symptoms are observed in lateral roots of both genotypes.
Publikation
Serra, P.; Hashemian, S.M.B.; Pensabene-Bellavia, G.; Gago, S.; Durán-Vila, N. An artifical chimeric derivative of Citrus viroid V involves the terminal left domain in pathogenicity Molecular Plant Pathology 10, 515-522, (2009) DOI: 10.1111/j.1364-3703.2009.00553.x
0