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.; Lamia, K.; Olfa, E.; Naïma, J.; Grubb, C. D.; Bassem, K.; Hafedh, M.; Amine, E. Morphological, Physiological and Biochemical
Impact of Ink Industry Effluent on Germination of Maize (Zea mays),
Barley (Hordeum vulgare) and Sorghum (Sorghum bicolor) Bull Environ Contam Toxicol 95, 687-693, (2015) DOI: 10.1007/s00128-015-1600-y
The present study focuses on effects of
untreated and treated ink industry wastewater on germination of maize,
barley and sorghum. Wastewater had a high chemical oxygen demand (COD)
and metal content compared to treated effluent. Germination decreased
with increasing COD concentration. Speed of germination also followed
the same trend, except for maize seeds exposed to untreated effluent
(E), which germinated slightly faster than controls. These alterations
of seedling development were mirrored by changes in soluble protein
content. E exerted a positive effect on soluble protein content and
maximum levels occurred after 10 days with treated effluent using
coagulation/flocculation (TEc/f) process and treated effluent using
combined process (coagulation/flocculation/biosorption) (TEc/f/b).
Likewise, activity of α-amylase was influenced by effluent composition.
Its expression depended on the species, exposure time and applied
treatment. Nevertheless, current results indicated TEc/f/b had no
observable toxic effects on germination and could be a beneficial
alternative resource to irrigation water.
Publikation
Flores, R.; Gago-Zachert, S.; Serra, P.; Sanjuán, R.; Elena, S. F. Viroids: Survivors from the RNA World? Annual Rev Microbiol 68, 395 - 414, (2014) DOI: 10.1146/annurev-micro-091313-103416
Because RNA can be a carrier of genetic information and a biocatalyst, there is a consensus that it emerged before DNA and proteins, which eventually assumed these roles and relegated RNA to intermediate functions. If such a scenario—the so-called RNA world—existed, we might hope to find its relics in our present world. The properties of viroids that make them candidates for being survivors of the RNA world include those expected for primitive RNA replicons: (a) small size imposed by error-prone replication, (b) high G+ C content to increase replication fidelity, (c) circular structure for assuring complete replication without genomic tags, (d) structural periodicity for modular assembly into enlarged genomes, (e) lack of protein-coding ability consistent with a ribosome-free habitat, and (f) replication mediated in some by ribozymes, the fingerprint of the RNA world. With the advent of DNA and proteins, those protoviroids lost some abilities and became the plant parasites we now know.
Publikation
Feussner, I.; Fritz, I.G.; Hause, B.; Ullrich, W.R.; Wasternack, C. Induction of a new lipoxygenase form in cucumber leaves by salicylic acid or 2,6-dichloroisonicotinic acid Bot. Acta 110, 101-108, (1997) DOI: 10.1111/j.1438-8677.1997.tb00616.x
Changes in lipoxygenase (LOX) protein pattern and/or activity were investigated in relation to acquired resistance of cucumber (Cucumis sativus L.) leaves against two powdery mildews, Sphaerotheca fuliginea (Schlecht) Salmon and Erysiphe cichoracearum DC et Merat. Acquired resistance was established by spraying leaves with salicylic acid (SA) or 2,6-dichloroisonicotinic acid (INA) and estimated in whole plants by infested leaf area compared to control plants. SA was more effective than INA. According to Western blots, untreated cucumber leaves contained a 97 kDa LOX form, which remained unchanged for up to 48 h after pathogen inoculation. Upon treatment with SA alone for 24 h or with INA plus pathogen, an additional 95 kDa LOX form appeared which had an isoelectric point in the alkaline range. For the induction of this form, a threshold concentration of 1 mM SA was required, higher SA concentrations did not change LOX-95 expression which remained similar between 24 h and 96 h but further increased upon mildew inoculation. Phloem exudates contained only the LOX-97 form, in intercellular washing fluid no LOX was detected. dichloroisonicotinic localization revealed LOX protein in the cytosol of the mesophyll cells without differences between the forms.