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Publikationen - Molekulare Signalverarbeitung

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Publikation

Gasperini, D.; Chauvin, A.; Acosta, I. F.; Kurenda, A.; Stolz, S.; Chételat, A.; Wolfender, J.-L.; Farmer, E. E.; Axial and Radial Oxylipin Transport Plant Physiol. 169, 2244-2254, (2015) DOI: 10.1104/pp.15.01104

Jasmonates are oxygenated lipids (oxylipins) that control defense gene expression in response to cell damage in plants. How mobile are these potent mediators within tissues? Exploiting a series of 13-lipoxygenase (13-lox) mutants in Arabidopsis (Arabidopsis thaliana) that displays impaired jasmonic acid (JA) synthesis in specific cell types and using JA-inducible reporters, we mapped the extent of the transport of endogenous jasmonates across the plant vegetative growth phase. In seedlings, we found that jasmonate (or JA precursors) could translocate axially from wounded shoots to unwounded roots in a LOX2-dependent manner. Grafting experiments with the wild type and JA-deficient mutants confirmed shoot-to-root oxylipin transport. Next, we used rosettes to investigate radial cell-to-cell transport of jasmonates. After finding that the LOX6 protein localized to xylem contact cells was not wound inducible, we used the lox234 triple mutant to genetically isolate LOX6 as the only JA precursor-producing LOX in the plant. When a leaf of this mutant was wounded, the JA reporter gene was expressed in distal leaves. Leaf sectioning showed that JA reporter expression extended from contact cells throughout the vascular bundle and into extravascular cells, revealing a radial movement of jasmonates. Our results add a crucial element to a growing picture of how the distal wound response is regulated in rosettes, showing that both axial (shoot-to-root) and radial (cell-to-cell) transport of oxylipins plays a major role in the wound response. The strategies developed herein provide unique tools with which to identify intercellular jasmonate transport routes.
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

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

Wasternack, C.; How Jasmonates Earned their Laurels: Past and Present J. Plant Growth Regul. 34, 761-794, (2015) DOI: 10.1007/s00344-015-9526-5

The histories of research regarding all plant hormones are similar. Identification and structural elucidation have been followed by analyses of their biosynthesis, distributions, signaling cascades, roles in developmental or stress response programs, and crosstalk. Jasmonic acid (JA) and its derivatives comprise a group of plant hormones that were discovered recently, compared to auxin, abscisic acid, cytokinins, gibberellic acid, and ethylene. Nevertheless, there have been tremendous advances in JA research, following the general progression outlined above and parallel efforts focused on several other “new” plant hormones (brassinosteroids, salicylate, and strigolactones). This review focuses on historical aspects of the identification of jasmonates, and characterization of their biosynthesis, distribution, perception, signaling pathways, crosstalk with other hormones and roles in plant stress responses and development. The aim is to illustrate how our present knowledge on jasmonates was generated and how that influences current efforts to extend our knowledge.
Publikation

Budiharjo, A.; Chowdhury, S. P.; Dietel, K.; Beator, B.; Dolgova, O.; Fan, B.; Bleiss, W.; Ziegler, J.; Schmid, M.; Hartmann, A.; Borriss, R.; Transposon Mutagenesis of the Plant-Associated Bacillus amyloliquefaciens ssp. plantarum FZB42 Revealed That the nfrA and RBAM17410 Genes Are Involved in Plant-Microbe-Interactions PLOS ONE 9, e98267, (2014) DOI: 10.1371/journal.pone.0098267

Bacillus amyloliquefaciens ssp. plantarum FZB42 represents the prototype of Gram-positive plant growth promoting and biocontrol bacteria. In this study, we applied transposon mutagenesis to generate a transposon library, which was screened for genes involved in multicellular behavior and biofilm formation on roots as a prerequisite of plant growth promoting activity. Transposon insertion sites were determined by rescue-cloning followed by DNA sequencing. As in B. subtilis, the global transcriptional regulator DegU was identified as an activator of genes necessary for swarming and biofilm formation, and the DegU-mutant of FZB42 was found impaired in efficient root colonization. Direct screening of 3,000 transposon insertion mutants for plant-growth-promotion revealed the gene products of nfrA and RBAM_017140 to be essential for beneficial effects exerted by FZB42 on plants. We analyzed the performance of GFP-labeled wild-type and transposon mutants in the colonization of lettuce roots using confocal laser scanning microscopy. While the wild-type strain heavily colonized root surfaces, the nfrA mutant did not colonize lettuce roots, although it was not impaired in growth in laboratory cultures, biofilm formation and swarming motility on agar plates. The RBAM17410 gene, occurring in only a few members of the B. subtilis species complex, was directly involved in plant growth promotion. None of the mutant strains were affected in producing the plant growth hormone auxin. We hypothesize that the nfrA gene product is essential for overcoming the stress caused by plant response towards bacterial root colonization.
Publikation

Bosch, M.; Wright, L. P.; Gershenzon, J.; Wasternack, C.; Hause, B.; Schaller, A.; Stintzi, A.; Jasmonic Acid and Its Precursor 12-Oxophytodienoic Acid Control Different Aspects of Constitutive and Induced Herbivore Defenses in Tomato Plant Physiol. 166, 396-410, (2014) DOI: 10.1104/pp.114.237388

The jasmonate family of growth regulators includes the isoleucine (Ile) conjugate of jasmonic acid (JA-Ile) and its biosynthetic precursor 12-oxophytodienoic acid (OPDA) as signaling molecules. To assess the relative contribution of JA/JA-Ile and OPDA to insect resistance in tomato (Solanum lycopersicum), we silenced the expression of OPDA reductase3 (OPR3) by RNA interference (RNAi). Consistent with a block in the biosynthetic pathway downstream of OPDA, OPR3-RNAi plants contained wild-type levels of OPDA but failed to accumulate JA or JA-Ile after wounding. JA/JA-Ile deficiency in OPR3-RNAi plants resulted in reduced trichome formation and impaired monoterpene and sesquiterpene production. The loss of these JA/JA-Ile -dependent defense traits rendered them more attractive to the specialist herbivore Manduca sexta with respect to feeding and oviposition. Oviposition preference resulted from reduced levels of repellant monoterpenes and sesquiterpenes. Feeding preference, on the other hand, was caused by increased production of cis-3-hexenal acting as a feeding stimulant for M. sexta larvae in OPR3-RNAi plants. Despite impaired constitutive defenses and increased palatability of OPR3-RNAi leaves, larval development was indistinguishable on OPR3-RNAi and wild-type plants, and was much delayed compared with development on the jasmonic acid-insensitive1 (jai1) mutant. Apparently, signaling through JAI1, the tomato ortholog of the ubiquitin ligase CORONATINE INSENSITIVE1 in Arabidopsis (Arabidopsis thaliana), is required for defense, whereas the conversion of OPDA to JA/JA-Ile is not. Comparing the signaling activities of OPDA and JA/JA-Ile, we found that OPDA can substitute for JA/JA-Ile in the local induction of defense gene expression, but the production of JA/JA-Ile is required for a systemic response.
Publikation

Antolín-Llovera, M.; Petutsching, E. K.; Ried, M. K.; Lipka, V.; Nürnberger, T.; Robatzek, S.; Parniske, M.; Knowing your friends and foes - plant receptor-like kinases as initiators of symbiosis or defence New Phytol. 204, 791-802, (2014) DOI: 10.1111/nph.13117

The decision between defence and symbiosis signalling in plants involves alternative and modular plasma membrane‐localized receptor complexes. A critical step in their activation is ligand‐induced homo‐ or hetero‐oligomerization of leucine‐rich repeat (LRR)‐ and/or lysin motif (LysM) receptor‐like kinases (RLKs). In defence signalling, receptor complexes form upon binding of pathogen‐associated molecular patterns (PAMPs), including the bacterial flagellin‐derived peptide flg22, or chitin. Similar mechanisms are likely to operate during the perception of microbial symbiont‐derived (lipo)‐chitooligosaccharides. The structurally related chitin‐oligomer ligands chitooctaose and chitotetraose trigger defence and symbiosis signalling, respectively, and their discrimination involves closely related, if not identical, LysM‐RLKs. This illustrates the demand for and the challenges imposed on decision mechanisms that ensure appropriate signal initiation. Appropriate signalling critically depends on abundance and localization of RLKs at the cell surface. This is regulated by internalization, which also provides a mechanism for the removal of activated signalling RLKs. Abundance of the malectin‐like domain (MLD)‐LRR‐RLK Symbiosis Receptor‐like Kinase (SYMRK) is additionally controlled by cleavage of its modular ectodomain, which generates a truncated and rapidly degraded RLK fragment. This review explores LRR‐ and LysM‐mediated signalling, the involvement of MLD‐LRR‐RLKs in symbiosis and defence, and the role of endocytosis in RLK function.
Publikation

Antolín-Llovera, M.; Ried, M. K.; Parniske, M.; Cleavage of the SYMBIOSIS RECEPTOR-LIKE KINASE Ectodomain Promotes Complex Formation with Nod Factor Receptor 5 Curr. Biol. 24, 422-427, (2014) DOI: 10.1016/j.cub.2013.12.053

Plants form root symbioses with fungi and bacteria to improve their nutrient supply. SYMBIOSIS RECEPTOR-LIKE KINASE (SYMRK) is required for phosphate-acquiring arbuscular mycorrhiza, as well as for the nitrogen-fixing root nodule symbiosis of legumes [1] and actinorhizal plants [2, 3], but its precise function was completely unclear. Here we show that the extracytoplasmic region of SYMRK, which comprises three leucine-rich repeats (LRRs) and a malectin-like domain (MLD) related to a carbohydrate-binding protein from Xenopus laevis [4], is cleaved to release the MLD in the absence of symbiotic stimulation. A conserved sequence motif—GDPC—that connects the MLD to the LRRs is required for MLD release. We discovered that Nod factor receptor 5 (NFR5) [5, 6, 7, 8] forms a complex with the SYMRK version that remains after MLD release (SYMRK-ΔMLD). SYMRK-ΔMLD outcompeted full-length SYMRK for NFR5 interaction, indicating that the MLD negatively interferes with complex formation. SYMRK-ΔMLD is present at lower amounts than MLD, suggesting rapid degradation after MLD release. A deletion of the entire extracytoplasmic region increased protein abundance, suggesting that the LRR region promotes degradation. Curiously, this deletion led to excessive infection thread formation, highlighting the importance of fine-tuned regulation of SYMRK by its ectodomain.
Publikation

Song, S.; Qi, T.; Wasternack, C.; Xie, D.; Jasmonate signaling and crosstalk with gibberellin and ethylene Curr. Opin. Plant Biol. 21, 112-119, (2014) DOI: 10.1016/j.pbi.2014.07.005

The phytohormone jasmonate (JA) plays essential roles in plant growth, development and defense. In response to the JA signal, the CORONATINE INSENSITIVE 1 (COI1)-based SCF complexes recruit JASMONATE ZIM-domain (JAZ) repressors for ubiquitination and degradation, and subsequently regulate their downstream signaling components essential for various JA responses. Tremendous progress has been made in understanding the JA signaling pathway and its crosstalk with other phytohormone pathways during the past two decades. Recent studies have revealed that a variety of positive and negative regulators act as targets of JAZs to control distinctive JA responses, and that JAZs and these regulators function as crucial interfaces to mediate synergy and antagonism between JA and other phytohormones. Owing to different regulatory players in JA perception and JA signaling, a fine-tuning of JA-dependent processes in plant growth, development and defense is achieved. In this review, we will summarize the latest progresses in JA signaling and its crosstalk with gibberellin and ethylene.
Publikation

Ried, M. K.; Antolín-Llovera, M.; Parniske, M.; Spontaneous symbiotic reprogramming of plant roots triggered by receptor-like kinases eLife 3, e03891, (2014) DOI: 10.7554/eLife.03891

Symbiosis Receptor-like Kinase (SYMRK) is indispensable for the development of phosphate-acquiring arbuscular mycorrhiza (AM) as well as nitrogen-fixing root nodule symbiosis, but the mechanisms that discriminate between the two distinct symbiotic developmental fates have been enigmatic. In this study, we show that upon ectopic expression, the receptor-like kinase genes Nod Factor Receptor 1 (NFR1), NFR5, and SYMRK initiate spontaneous nodule organogenesis and nodulation-related gene expression in the absence of rhizobia. Furthermore, overexpressed NFR1 or NFR5 associated with endogenous SYMRK in roots of the legume Lotus japonicus. Epistasis tests revealed that the dominant active SYMRK allele initiates signalling independently of either the NFR1 or NFR5 gene and upstream of a set of genes required for the generation or decoding of calcium-spiking in both symbioses. Only SYMRK but not NFR overexpression triggered the expression of AM-related genes, indicating that the receptors play a key role in the decision between AM- or root nodule symbiosis-development.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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