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Phosphate (Pi) availability has a strong influence on the symbiotic interaction between Arabidopsis and a recently described root-colonizing beneficial Trichoderma harzianum strain. When transferred to media with insoluble Ca3(PO4)2 as a sole Pi source, Arabidopsis seedlings died after 10 days. Trichoderma grew on the medium containing Ca3(PO4)2 and the fungus did colonize in roots, stems, and shoots of the host. The efficiency of the photosynthetic electron transport of the colonized seedlings grown on Ca3(PO4)2 medium was reduced and the seedlings died earlier, indicating that the fungus exerts an additional stress to the plant. Interestingly, the fungus initially alleviated the Pi starvation response and did not activate defense responses against the hyphal propagation. However, in colonized roots, the sucrose transporter genes SWEET11 and -12 were strongly down-regulated, restricting the unloading of sucrose from the phloem parenchyma cells to the apoplast. Simultaneously, up-regulation of SUC1 promoted sucrose uptake from the apoplast into the parenchyma cells and of SWEET2 sequestration of sucrose in the vacuole of the root cells. We propose that the fungus tries to escape from the Ca3(PO4)2 medium and colonizes the entire host. To prevent excessive sugar consumption by the propagating hyphae, the host restricts sugar availability in its apoplastic root space by downregulating sugar transporter genes for phloem unloading, and by upregulating transporter genes which maintain the sugar in the root cells.
Hamid Rouina; Yu-Heng Tseng; Karaba Nataraja; Ramanan Uma Shaanker; Ralf Oelmüller. Arabidopsis Restricts Sugar Loss to a Colonizing Trichoderma harzianum Strain by Downregulating SWEET11 and -12 and Upregulation of SUC1 and SWEET2 in the Roots. Microorganisms 2021, 9, 1246 .
AMA StyleHamid Rouina, Yu-Heng Tseng, Karaba Nataraja, Ramanan Uma Shaanker, Ralf Oelmüller. Arabidopsis Restricts Sugar Loss to a Colonizing Trichoderma harzianum Strain by Downregulating SWEET11 and -12 and Upregulation of SUC1 and SWEET2 in the Roots. Microorganisms. 2021; 9 (6):1246.
Chicago/Turabian StyleHamid Rouina; Yu-Heng Tseng; Karaba Nataraja; Ramanan Uma Shaanker; Ralf Oelmüller. 2021. "Arabidopsis Restricts Sugar Loss to a Colonizing Trichoderma harzianum Strain by Downregulating SWEET11 and -12 and Upregulation of SUC1 and SWEET2 in the Roots." Microorganisms 9, no. 6: 1246.
Endophytic bacteria colonize plants and live inside them for part of or throughout their life without causing any harm or disease to their hosts. The symbiotic relationship improves the physiology, fitness, and metabolite profile of the plants, while the plants provide food and shelter for the bacteria. The bacteria-induced alterations of the plants offer many possibilities for biotechnological, medicinal, and agricultural applications. The endophytes promote plant growth and fitness through the production of phytohormones or biofertilizers, or by alleviating abiotic and biotic stress tolerance. Strengthening of the plant immune system and suppression of disease are associated with the production of novel antibiotics, secondary metabolites, siderophores, and fertilizers such as nitrogenous or other industrially interesting chemical compounds. Endophytic bacteria can be used for phytoremediation of environmental pollutants or the control of fungal diseases by the production of lytic enzymes such as chitinases and cellulases, and their huge host range allows a broad spectrum of applications to agriculturally and pharmaceutically interesting plant species. More recently, endophytic bacteria have also been used to produce nanoparticles for medical and industrial applications. This review highlights the biotechnological possibilities for bacterial endophyte applications and proposes future goals for their application.
Ahmed Eid; Amr Fouda; Mohamed Abdel-Rahman; Salem Salem; Albaraa Elsaied; Ralf Oelmüller; Mohamed Hijri; Arnab Bhowmik; Amr Elkelish; Saad Hassan. Harnessing Bacterial Endophytes for Promotion of Plant Growth and Biotechnological Applications: An Overview. Plants 2021, 10, 935 .
AMA StyleAhmed Eid, Amr Fouda, Mohamed Abdel-Rahman, Salem Salem, Albaraa Elsaied, Ralf Oelmüller, Mohamed Hijri, Arnab Bhowmik, Amr Elkelish, Saad Hassan. Harnessing Bacterial Endophytes for Promotion of Plant Growth and Biotechnological Applications: An Overview. Plants. 2021; 10 (5):935.
Chicago/Turabian StyleAhmed Eid; Amr Fouda; Mohamed Abdel-Rahman; Salem Salem; Albaraa Elsaied; Ralf Oelmüller; Mohamed Hijri; Arnab Bhowmik; Amr Elkelish; Saad Hassan. 2021. "Harnessing Bacterial Endophytes for Promotion of Plant Growth and Biotechnological Applications: An Overview." Plants 10, no. 5: 935.
Adaptation and response to environmental changes require dynamic and fast information distribution within the plant body. If one part of a plant is exposed to stress, attacked by other organisms or exposed to any other kind of threat, the information travels to neighboring organs and even neighboring plants and activates appropriate responses. The information flow is mediated by fast-traveling small metabolites, hormones, proteins/peptides, RNAs or volatiles. Electric and hydraulic waves also participate in signal propagation. The signaling molecules move from one cell to the neighboring cell, via the plasmodesmata, through the apoplast, within the vascular tissue or—as volatiles—through the air. A threat-specific response in a systemic tissue probably requires a combination of different traveling compounds. The propagating signals must travel over long distances and multiple barriers, and the signal intensity declines with increasing distance. This requires permanent amplification processes, feedback loops and cross-talks among the different traveling molecules and probably a short-term memory, to refresh the propagation process. Recent studies show that volatiles activate defense responses in systemic tissues but also play important roles in the maintenance of the propagation of traveling signals within the plant. The distal organs can respond immediately to the systemic signals or memorize the threat information and respond faster and stronger when they are exposed again to the same or even another threat. Transmission and storage of information is accompanied by loss of specificity about the threat that activated the process. I summarize our knowledge about the proposed long-distance traveling compounds and discuss their possible connections.
Ralf Oelmüller. Threat at One End of the Plant: What Travels to Inform the Other Parts? International Journal of Molecular Sciences 2021, 22, 3152 .
AMA StyleRalf Oelmüller. Threat at One End of the Plant: What Travels to Inform the Other Parts? International Journal of Molecular Sciences. 2021; 22 (6):3152.
Chicago/Turabian StyleRalf Oelmüller. 2021. "Threat at One End of the Plant: What Travels to Inform the Other Parts?" International Journal of Molecular Sciences 22, no. 6: 3152.
Background Erwinia chrysanthemi (Ec) is a destructive pathogen which causes soft-rot diseases in diverse plant species including orchids. We investigated whether colonization of Oncidium roots by the endophytic fungus Piriformospora indica (Pi) restricts Ec-induced disease development in leaves, and whether this might be related to the regulation of nucleotide binding site-leucine rich repeat (NBS-LRR) Resistance (R) genes. Results Root colonization of Oncidium stackings by Pi restricts progression of Ec-induced disease development in the leaves. Since Pi does not inhibit Ec growth on agar plates, we tested whether NBS-LRR R gene transcripts and the levels of their potential target miRNAs in Oncidium leaves might be regulated by Pi. Using bioinformatic tools, we first identified NBS-LRR R gene sequences from Oncidium, which are predicted to be targets of miRNAs. Among them, the expression of two R genes was repressed and the accumulation of several regulatory miRNA stimulated by Ec in the leaves of Oncidium plants. This correlated with the progression of disease development, jasmonic and salicylic acid accumulation, ethylene synthesis and H2O2 production after Ec infection of Oncidium leaves. Interestingly, root colonization by Pi restricted disease development in the leaves, and this was accompanied by higher expression levels of several defense-related R genes and lower expression level of their target miRNA. Conclusion Based on these data we propose that Pi controls the levels of NBS-LRR R mRNAs and their target miRNAs in leaves. This regulatory circuit correlates with the protection of Oncidium plants against Ec infection, and molecular and biochemical investigations will demonstrate in the future whether, and if so, to what extent these two observations are related to each other.
Wei Ye; Jinlan Jiang; Yuling Lin; Kai-Wun Yeh; Zhongxiong Lai; Xuming Xu; Ralf Oelmüller. Colonisation of Oncidium orchid roots by the endophyte Piriformospora indica restricts Erwinia chrysanthemi infection, stimulates accumulation of NBS-LRR resistance gene transcripts and represses their targeting micro-RNAs in leaves. BMC Plant Biology 2019, 19, 1 -16.
AMA StyleWei Ye, Jinlan Jiang, Yuling Lin, Kai-Wun Yeh, Zhongxiong Lai, Xuming Xu, Ralf Oelmüller. Colonisation of Oncidium orchid roots by the endophyte Piriformospora indica restricts Erwinia chrysanthemi infection, stimulates accumulation of NBS-LRR resistance gene transcripts and represses their targeting micro-RNAs in leaves. BMC Plant Biology. 2019; 19 (1):1-16.
Chicago/Turabian StyleWei Ye; Jinlan Jiang; Yuling Lin; Kai-Wun Yeh; Zhongxiong Lai; Xuming Xu; Ralf Oelmüller. 2019. "Colonisation of Oncidium orchid roots by the endophyte Piriformospora indica restricts Erwinia chrysanthemi infection, stimulates accumulation of NBS-LRR resistance gene transcripts and represses their targeting micro-RNAs in leaves." BMC Plant Biology 19, no. 1: 1-16.
Plant are connected via hyphal networks which distribute nutrients, reduced carbon from photosynthesis as well as information within the plant community. I describe our current knowledge about these common mycelial networks, and address open questions that need to be answered to understand their role in ecosystems, pest management and sustainable agriculture. Besides numerous models describing the belowground interplant communication, only a little is known about the molecular basis and structural requirements for information transfer. However, established and novel model systems may provide a link between scientific approaches in the laboratory and ecologically relevant observations in nature.
Ralf Oelmüller. Interplant communication via hyphal networks. Plant Physiology Reports 2019, 24, 463 -473.
AMA StyleRalf Oelmüller. Interplant communication via hyphal networks. Plant Physiology Reports. 2019; 24 (4):463-473.
Chicago/Turabian StyleRalf Oelmüller. 2019. "Interplant communication via hyphal networks." Plant Physiology Reports 24, no. 4: 463-473.
Roots respond to a cocktail of chemicals from microbes in the rhizosphere. Infochemicals in nmol concentrations activate receptor-mediated signal pathways, which reprogram the plant responses to environmental changes. The microbial signals have to pass the cell wall to activate pattern recognition receptors at the surface of the plant plasma membrane. The structure of the cell wall is not only a barrier for the signaling molecules, but also changes permanently during growth and development, as well as in response to microbial attacks or abiotic stress. Recently, cellooligomers (COMs) were identified as novel chemical mediators in Arabidopsis thaliana, which inform the cell about the alterations in and around the cell wall. They can be of microbial and plant origin and represent novel invasion patterns (Cook et al., 2015). COMs initiate Ca2+-dependent signaling events that reprogram the cell and adjust the expression and metabolite profiles as well as innate immunity in response to changes in their rhizosphere environment and the state of the cell wall. COMs operate synergistically with other signals or their recognition machineries and activates local and systemic responses in the entire plant. They also adjust the performance of the areal parts of the plant to signals perceived by the roots. Here, I summarize our current knowledge about COMs and propose strategies for future investigations.
Ralf Oelmüller. Sensing environmental and developmental signals via cellooligomers. Journal of Plant Physiology 2018, 229, 1 -6.
AMA StyleRalf Oelmüller. Sensing environmental and developmental signals via cellooligomers. Journal of Plant Physiology. 2018; 229 ():1-6.
Chicago/Turabian StyleRalf Oelmüller. 2018. "Sensing environmental and developmental signals via cellooligomers." Journal of Plant Physiology 229, no. : 1-6.
Root colonization by endophytic fungus Piriformospora indica facilitating growth/development and stress tolerance has been demonstrated in various host plants. However, global metabolomic studies are rare. By using high-throughput gas-chromatography-based mass spectrometry, 549 metabolites of 1,126 total compounds observed were identified in colonized and uncolonized Chinese cabbage roots, and hyphae of P. indica. The analyses demonstrate that the host metabolomic compounds and metabolite pathways are globally reprogrammed after symbiosis with P. indica. Especially, γ-amino butyrate (GABA), oxylipin-family compounds, poly-saturated fatty acids, and auxin and its intermediates were highly induced and de novo synthesized in colonized roots. Conversely, nicotinic acid (niacin) and dimethylallylpyrophosphate were strongly decreased. In vivo assays with exogenously applied compounds confirmed that GABA primes plant immunity toward pathogen attack and enhances high salinity and temperature tolerance. Moreover, generation of reactive oxygen/nitrogen species stimulated by nicotinic acid is repressed by P. indica, and causes the feasibility of symbiotic interaction. This global metabolomic analysis and the identification of symbiosis-specific metabolites may help to understand how P. indica confers benefits to the host plant.
Mo Da-Sang Hua; Rajendran Senthil Kumar; Lie-Fen Shyur; Yuan-Bin Cheng; Zhihong Tian; Ralf Oelmüller; Kai-Wun Yeh. Metabolomic compounds identified in Piriformospora indica-colonized Chinese cabbage roots delineate symbiotic functions of the interaction. Scientific Reports 2017, 7, 1 -14.
AMA StyleMo Da-Sang Hua, Rajendran Senthil Kumar, Lie-Fen Shyur, Yuan-Bin Cheng, Zhihong Tian, Ralf Oelmüller, Kai-Wun Yeh. Metabolomic compounds identified in Piriformospora indica-colonized Chinese cabbage roots delineate symbiotic functions of the interaction. Scientific Reports. 2017; 7 (1):1-14.
Chicago/Turabian StyleMo Da-Sang Hua; Rajendran Senthil Kumar; Lie-Fen Shyur; Yuan-Bin Cheng; Zhihong Tian; Ralf Oelmüller; Kai-Wun Yeh. 2017. "Metabolomic compounds identified in Piriformospora indica-colonized Chinese cabbage roots delineate symbiotic functions of the interaction." Scientific Reports 7, no. 1: 1-14.
Piriformospora indica is an endophytic fungus of Sebacinaceae which colonizes the roots of many plant species and confers benefits to the hosts. We demonstrate that approximately 75% of the genes which respond to P. indica in Arabidopsis roots differ among seedlings grown on normal phosphate (Pi) or Pi limitation conditions, and among wild-type and the wrky6 mutant impaired in the regulation of the Pi metabolism. Mapman analyses suggest that the fungus activates different signaling, transport, metabolic and developmental programs in wild-type and wrky6 roots under normal and low Pi conditions. Under low Pi, P. indica promotes growth and Pi uptake of wild-type seedlings, and the stimulatory effects are identical for mutants impaired in the PHOSPHATE TRANSPORTERS1;1, -1;2 and -1;4. The data suggest that the fungus does not stimulate Pi uptake, but adapts the expression profiles to Pi limitation in Pi metabolism mutants.
Madhunita Bakshi; Irena Sherameti; Doreen Meichsner; Johannes Thürich; Ajit Varma; Atul K. Johri; Kai-Wun Yeh; Ralf Oelmüller. Piriformospora indica Reprograms Gene Expression in Arabidopsis Phosphate Metabolism Mutants But Does Not Compensate for Phosphate Limitation. Frontiers in Microbiology 2017, 8, 1262 -1262.
AMA StyleMadhunita Bakshi, Irena Sherameti, Doreen Meichsner, Johannes Thürich, Ajit Varma, Atul K. Johri, Kai-Wun Yeh, Ralf Oelmüller. Piriformospora indica Reprograms Gene Expression in Arabidopsis Phosphate Metabolism Mutants But Does Not Compensate for Phosphate Limitation. Frontiers in Microbiology. 2017; 8 ():1262-1262.
Chicago/Turabian StyleMadhunita Bakshi; Irena Sherameti; Doreen Meichsner; Johannes Thürich; Ajit Varma; Atul K. Johri; Kai-Wun Yeh; Ralf Oelmüller. 2017. "Piriformospora indica Reprograms Gene Expression in Arabidopsis Phosphate Metabolism Mutants But Does Not Compensate for Phosphate Limitation." Frontiers in Microbiology 8, no. : 1262-1262.
The beneficial root-colonizing fungus Piriformospora indica stimulates root development of Chinese cabbage (Brassica campestris subsp. Chinensis) and this is accompanied by the up-regulation of a τ-class glutathione (GSH)-S-transferase gene (BcGSTU) (Lee et al. 2011) in the roots. BcGSTU expression is further promoted by osmotic (salt and PEG) and heat stress. Ectopic expression of BcGSTU in Arabidopsis under the control of the 35S promoter results in the promotion of root and shoot growth as well as better performance of the plants under abiotic (150 mM NaCl, PEG, 42 °C) and biotic (Alternaria brassicae infection) stresses. Higher levels of glutathione, auxin and stress-related (salicylic and jasmonic acid) phytohormones as well as changes in the gene expression profile result in better performance of the BcGSTU expressors upon exposure to stress. Simultaneously the plants are primed against upcoming stresses. We propose that BcGSTU is a target of P. indica in Chinese cabbage roots because the enzyme participates in balancing growth and stress responses, depending on the equilibrium of the symbiotic interaction. A comparable function of BcGST in transgenic Arabidopsis makes the enzyme a valuable tool for agricultural applications.
Chih-Wei Kao; Madhunita Bakshi; Irena Sherameti; Sheqin Dong; Michael Reichelt; Ralf Oelmüller; Kai-Wun Yeh. A Chinese cabbage (Brassica campetris subsp. Chinensis) τ-type glutathione-S-transferase stimulates Arabidopsis development and primes against abiotic and biotic stress. Plant Molecular Biology 2016, 92, 643 -659.
AMA StyleChih-Wei Kao, Madhunita Bakshi, Irena Sherameti, Sheqin Dong, Michael Reichelt, Ralf Oelmüller, Kai-Wun Yeh. A Chinese cabbage (Brassica campetris subsp. Chinensis) τ-type glutathione-S-transferase stimulates Arabidopsis development and primes against abiotic and biotic stress. Plant Molecular Biology. 2016; 92 (6):643-659.
Chicago/Turabian StyleChih-Wei Kao; Madhunita Bakshi; Irena Sherameti; Sheqin Dong; Michael Reichelt; Ralf Oelmüller; Kai-Wun Yeh. 2016. "A Chinese cabbage (Brassica campetris subsp. Chinensis) τ-type glutathione-S-transferase stimulates Arabidopsis development and primes against abiotic and biotic stress." Plant Molecular Biology 92, no. 6: 643-659.
The endophytic fungus Piriformospora indica colonizes Arabidopsis thaliana roots and promotes plant performance, growth and resistance/tolerance against abiotic and biotic stress. Here we demonstrate that the benefits for the plant increase when the two partners are co-cultivated under stress (limited access to nutrient, exposure to heavy metals and salt, light and osmotic stress, pathogen infection). Moreover, physical contact between P. indica and Arabidopsis roots is necessary for optimal growth promotion, and chemical communication cannot replace the physical contact. Lower nutrient availability down-regulates and higher nutrient availability up-regulates the plant defense system including the expression of pathogenesis-related genes in roots. High light, osmotic and salt stresses support the beneficial interaction between the plant and the fungus. P. indica reduces stomata closure and H2O2 production after Alternaria brassicae infection in leaves and suppresses the defense-related accumulation of the phytohormone jasmonic acid. Thus, shifting the growth conditions toward a stress promotes the mutualistic interaction, while optimal supply with nutrients or low stress diminishes the benefits for the plant in the symbiosis.
Khabat Vahabi; Sedigheh Karimi Dorcheh; Shamci Monajembashi; Martin Westermann; Michael Reichelt; Daniela Falkenberg; Peter Hemmerich; Irena Sherameti; Ralf Oelmüller. Stress promotes Arabidopsis - Piriformospora indica interaction. Plant Signaling & Behavior 2016, 11, e1136763 .
AMA StyleKhabat Vahabi, Sedigheh Karimi Dorcheh, Shamci Monajembashi, Martin Westermann, Michael Reichelt, Daniela Falkenberg, Peter Hemmerich, Irena Sherameti, Ralf Oelmüller. Stress promotes Arabidopsis - Piriformospora indica interaction. Plant Signaling & Behavior. 2016; 11 (5):e1136763.
Chicago/Turabian StyleKhabat Vahabi; Sedigheh Karimi Dorcheh; Shamci Monajembashi; Martin Westermann; Michael Reichelt; Daniela Falkenberg; Peter Hemmerich; Irena Sherameti; Ralf Oelmüller. 2016. "Stress promotes Arabidopsis - Piriformospora indica interaction." Plant Signaling & Behavior 11, no. 5: e1136763.
Arabidopsis root growth is stimulated by Piriformospora indica, phosphate limitation and inactivation of the WRKY6 transcription factor. Combinations of these factors induce unexpected alterations in root and shoot growth, root architecture and root gene expression profiles. The results demonstrate that P. indica promotes phosphate uptake and root development under Pi limitation in wrky6 mutant. This is associated with the stimulation of PHOSPHATE1 expression and ethylene production. Expression profiles from the roots of wrky6 seedlings identified genes involved in hormone metabolism, transport, meristem, cell and plastid proliferation, and growth regulation. 25 miRNAs were also up-regulated in these roots. We generated and discuss here a list of common genes which are regulated in growing roots and which are common to all three growth stimuli investigated in this study. Since root development of wrky6 plants exposed to P. indica under phosphate limitation is strongly promoted, we propose that common genes which respond to all three growth stimuli are central for the control of root growth and architecture. They can be tested for optimizing root growth in model and agricultural plants.
Madhunita Bakshi; Khabat Vahabi; Samik Bhattacharya; Irena Sherameti; Ajit Varma; Kai-Wun Yeh; Ian T Baldwin; Atul Kumar Johri; Ralf Oelmüller. WRKY6 restricts Piriformospora indica-stimulated and phosphate-induced root development in Arabidopsis. BMC Plant Biology 2015, 15, 1 -19.
AMA StyleMadhunita Bakshi, Khabat Vahabi, Samik Bhattacharya, Irena Sherameti, Ajit Varma, Kai-Wun Yeh, Ian T Baldwin, Atul Kumar Johri, Ralf Oelmüller. WRKY6 restricts Piriformospora indica-stimulated and phosphate-induced root development in Arabidopsis. BMC Plant Biology. 2015; 15 (1):1-19.
Chicago/Turabian StyleMadhunita Bakshi; Khabat Vahabi; Samik Bhattacharya; Irena Sherameti; Ajit Varma; Kai-Wun Yeh; Ian T Baldwin; Atul Kumar Johri; Ralf Oelmüller. 2015. "WRKY6 restricts Piriformospora indica-stimulated and phosphate-induced root development in Arabidopsis." BMC Plant Biology 15, no. 1: 1-19.
REDOX RESPONSIVE TRANSCRIPTION FACTOR1 (RRTF1) regulates redox homeostasis under stress, however the mechanism is mainly unknown. In a recent publication, we analyzed rrtf1 knockout (ko) and RRTF1 overexpressor lines of Arabidopsis thaliana and showed that RRTF1 plays a crucial role in reactive oxygen species (ROS) production. Ko line produces less and overexpressor lines constitutively high levels of ROS under stress, and the amount of ROS increases with increase in stress and the RRTF1 level in the plant. The transcription factor also activates systemic ROS signaling under stress.1 Matsuo M, Johnson JM, Hieno A, Tokizawa M, Nomoto M, Tada Y, Godfrey R, Obokata J, Sherameti I, Yamamoto YY, et al. High REDOX RESPONSIVE TRANSCRIPTION FACTOR1 levels result in accumulation of reactive oxygen species in Arabidopsis thaliana shoots and roots. Mol Plant (2015); 8;1253-73. doi:10.1016/j.molp.2015.03.011. http://dx.doi.org/10.1016/j.molp.2015.03.011[Crossref], [PubMed], [Web of Science ®] [Google Scholar] In this report, we show that RRTF1 exerts different roles in young and old leaves. While RRTF1 enhances defense responses to high light (HL) stress in young leaves, it induces senescence and chlorosis in older leaves. These findings suggest that RRTF1 and/or RRTF1-mediated ROS signaling induce stress responses in an age-dependent manner, and the age-dependent alteration in the RRTF1 function might be important for plants' acclimation to the stress environment.
Mitsuhiro Matsuo; Ralf Oelmüller. REDOX RESPONSIVE TRANSCRIPTION FACTOR1 is involved in age-dependent and systemic stress signaling. Plant Signaling & Behavior 2015, 10, e1051279 .
AMA StyleMitsuhiro Matsuo, Ralf Oelmüller. REDOX RESPONSIVE TRANSCRIPTION FACTOR1 is involved in age-dependent and systemic stress signaling. Plant Signaling & Behavior. 2015; 10 (11):e1051279.
Chicago/Turabian StyleMitsuhiro Matsuo; Ralf Oelmüller. 2015. "REDOX RESPONSIVE TRANSCRIPTION FACTOR1 is involved in age-dependent and systemic stress signaling." Plant Signaling & Behavior 10, no. 11: e1051279.
Piriformospora indica, an endophytic fungus of Sebacinales, colonizes the roots of many plant species including Arabidopsis thaliana. The symbiotic interaction promotes plant performance, growth and resistance/tolerance against abiotic and biotic stress. We demonstrate that exudated compounds from the fungus activate stress and defense responses in the Arabidopsis roots and shoots before the two partners are in physical contact. They induce stomata closure, stimulate reactive oxygen species (ROS) production, stress-related phytohormone accumulation and activate defense and stress genes in the roots and/or shoots. Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the number and expression level of defense/stress-related genes decreases. We propose that exudated compounds from P. indica induce stress and defense responses in the host. Root colonization results in the down-regulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance.
Khabat Vahabi; Irena Sherameti; Madhunita Bakshi; Anna Mrozinska; Anatoli Ludwig; Michael Reichelt; Ralf Oelmüller. The interaction of Arabidopsis with Piriformospora indica shifts from initial transient stress induced by fungus-released chemical mediators to a mutualistic interaction after physical contact of the two symbionts. BMC Plant Biology 2015, 15, 1 -15.
AMA StyleKhabat Vahabi, Irena Sherameti, Madhunita Bakshi, Anna Mrozinska, Anatoli Ludwig, Michael Reichelt, Ralf Oelmüller. The interaction of Arabidopsis with Piriformospora indica shifts from initial transient stress induced by fungus-released chemical mediators to a mutualistic interaction after physical contact of the two symbionts. BMC Plant Biology. 2015; 15 (1):1-15.
Chicago/Turabian StyleKhabat Vahabi; Irena Sherameti; Madhunita Bakshi; Anna Mrozinska; Anatoli Ludwig; Michael Reichelt; Ralf Oelmüller. 2015. "The interaction of Arabidopsis with Piriformospora indica shifts from initial transient stress induced by fungus-released chemical mediators to a mutualistic interaction after physical contact of the two symbionts." BMC Plant Biology 15, no. 1: 1-15.
Verticillium dahliae (Vd) is a soil-borne vascular pathogen which causes severe wilt symptoms in a wide range of plants. The microsclerotia produced by the pathogen survive in soil for more than 15 years. Here we demonstrate that an exudate preparation induces cytoplasmic calcium elevation in Arabidopsis roots, and the disease development requires the ethylene-activated transcription factor EIN3. Furthermore, the beneficial endophytic fungus Piriformospora indica (Pi) significantly reduced Vd-mediated disease development in Arabidopsis. Pi inhibited the growth of Vd in a dual culture on PDA agar plates and pretreatment of Arabidopsis roots with Pi protected plants from Vd infection. The Pi-pretreated plants grew better after Vd infection and the production of Vd microsclerotia was dramatically reduced, all without activating stress hormones and defense genes in the host. We conclude that Pi is an efficient biocontrol agent that protects Arabidopsis from Vd infection. Our data demonstrate that Vd growth is restricted in the presence of Pi and the additional signals from Pi must participate in the regulation of the immune response against Vd.
Chao Sun; Yongqi Shao; Khabat Vahabi; Jing Lu; Samik Bhattacharya; Sheqin Dong; Kai-Wun Yeh; Irena Sherameti; Binggan Lou; Ian T Baldwin; Ralf Oelmüller. The beneficial fungus Piriformospora indica protects Arabidopsis from Verticillium dahliae infection by downregulation plant defense responses. BMC Plant Biology 2014, 14, 268 .
AMA StyleChao Sun, Yongqi Shao, Khabat Vahabi, Jing Lu, Samik Bhattacharya, Sheqin Dong, Kai-Wun Yeh, Irena Sherameti, Binggan Lou, Ian T Baldwin, Ralf Oelmüller. The beneficial fungus Piriformospora indica protects Arabidopsis from Verticillium dahliae infection by downregulation plant defense responses. BMC Plant Biology. 2014; 14 (1):268.
Chicago/Turabian StyleChao Sun; Yongqi Shao; Khabat Vahabi; Jing Lu; Samik Bhattacharya; Sheqin Dong; Kai-Wun Yeh; Irena Sherameti; Binggan Lou; Ian T Baldwin; Ralf Oelmüller. 2014. "The beneficial fungus Piriformospora indica protects Arabidopsis from Verticillium dahliae infection by downregulation plant defense responses." BMC Plant Biology 14, no. 1: 268.
The 1st International Conference on “Biotechnology in Agriculture” was held at the Agricultural University of Tirana, Albania, from the 22nd to the 23rd of April 2014. The conference was organized as collaboration between the Agricultural University of Tirana (AUT) and the Friedrich Schiller University in Jena, Germany. About 200 scientists from different countries presented their work orally or as posters covering the three main topics of the conference: plant, animal and food biotechnology. The conference included a field trip as well to the Experimental Didactic Economy Station and a Fish Farm, both belonging to the Agricultural University of Tirana. In this report, we describe the main topics of the Conference and a summary of talks and posters presented in different sessions. The main conclusions provided at the end of the activity, the objectives for the future and a brief overview of the field trips and pre- and post-conference tours are displayed in this current report. Since the conference on “Biotechnology in Agriculture” was the first one organized in Albania and also an international one, it was of a great interest for the participants and also for the scientific community working in the biotechnology area. Therefore, one of the decisions made at the end of the conference was to hold similar conferences periodically, every two years, at AUT.
Anila Hoda; Irena Sherameti; Fatos Harizaj; Bizena Bijo; Helmut König; Ralf Oelmüller. First International Conference on “Biotechnology in Agriculture”. Journal of Plant Growth Regulation 2014, 33, 697 -708.
AMA StyleAnila Hoda, Irena Sherameti, Fatos Harizaj, Bizena Bijo, Helmut König, Ralf Oelmüller. First International Conference on “Biotechnology in Agriculture”. Journal of Plant Growth Regulation. 2014; 33 (3):697-708.
Chicago/Turabian StyleAnila Hoda; Irena Sherameti; Fatos Harizaj; Bizena Bijo; Helmut König; Ralf Oelmüller. 2014. "First International Conference on “Biotechnology in Agriculture”." Journal of Plant Growth Regulation 33, no. 3: 697-708.
WRKY transcription factors are one of the largest families of transcriptional regulators found exclusively in plants. They have diverse biological functions in plant disease resistance, abiotic stress responses, nutrient deprivation, senescence, seed and trichome development, embryogenesis, as well as additional developmental and hormone-controlled processes. WRKYs can act as transcriptional activators or repressors, in various homo- and heterodimer combinations. Here we review recent progress on the function of WRKY transcription factors in Arabidopsis and other plant species such as rice, potato, and parsley, with a special focus on abiotic, developmental, and hormone-regulated processes.
Madhunita Bakshi; Ralf Oelmüller. WRKY transcription factors. Plant Signaling & Behavior 2014, 9, e27700 .
AMA StyleMadhunita Bakshi, Ralf Oelmüller. WRKY transcription factors. Plant Signaling & Behavior. 2014; 9 (2):e27700.
Chicago/Turabian StyleMadhunita Bakshi; Ralf Oelmüller. 2014. "WRKY transcription factors." Plant Signaling & Behavior 9, no. 2: e27700.
Ca2+, a versatile intracellular second messenger in various signaling pathways, initiates many responses involved in growth, defense and tolerance to biotic and abiotic stress. Endogenous and exogenous signals induce cytoplasmic Ca2+ ([Ca2+]cyt) elevation, which are responsible for the appropriate downstream responses.
Joy Michal Johnson; Michael Reichelt; Jyothilakshmi Vadassery; Jonathan Gershenzon; Ralf Oelmüller. An Arabidopsis mutant impaired in intracellular calcium elevation is sensitive to biotic and abiotic stress. BMC Plant Biology 2014, 14, 162 -162.
AMA StyleJoy Michal Johnson, Michael Reichelt, Jyothilakshmi Vadassery, Jonathan Gershenzon, Ralf Oelmüller. An Arabidopsis mutant impaired in intracellular calcium elevation is sensitive to biotic and abiotic stress. BMC Plant Biology. 2014; 14 (1):162-162.
Chicago/Turabian StyleJoy Michal Johnson; Michael Reichelt; Jyothilakshmi Vadassery; Jonathan Gershenzon; Ralf Oelmüller. 2014. "An Arabidopsis mutant impaired in intracellular calcium elevation is sensitive to biotic and abiotic stress." BMC Plant Biology 14, no. 1: 162-162.
The endophytic fungus Piriformospora indica colonizes the roots of many plant species including Arabidopsis and promotes their performance, biomass, and seed production as well as resistance against biotic and abiotic stress. Imbalances in the symbiotic interaction such as uncontrolled fungal growth result in the loss of benefits for the plants and activation of defense responses against the microbe. We exposed Arabidopsis seedlings to a dense hyphal lawn of P. indica. The seedlings continue to grow, accumulate normal amounts of chlorophyll, and the photosynthetic parameters demonstrate that they perform well. In spite of high fungal doses around the roots, the fungal material inside the roots was not significantly higher when compared with roots that live in a beneficial symbiosis with P. indica. Fifteen defense- and stress-related genes including PR2, PR3, PAL2, and ERF1 are only moderately upregulated in the roots on the fungal lawn, and the seedlings did not accumulate H2O2/radical oxygen species. However, accumulation of anthocyanin in P. indica-exposed seedlings indicates stress symptoms. Furthermore, the jasmonic acid (JA) and jasmonic acid-isoleucine (JA-Ile) levels were increased in the roots, and consequently PDF1.2 and a newly characterized gene for a 2-oxoglurate and Fe2+-dependent oxygenase were upregulated more than 7-fold on the dense fungal lawn, in a JAR1- and EIN3-dependent manner. We conclude that growth of A. thaliana seedlings on high fungal doses of P. indica has little effect on the overall performance of the plants although elevated JA and JA-Ile levels in the roots induce a mild stress or defense response.
Khabat Vahabi; Iris Camehl; Irena Sherameti; Ralf Oelmüller. Growth ofArabidopsisseedlings on high fungal doses ofPiriformospora indicahas little effect on plant performance, stress, and defense gene expression in spite of elevated jasmonic acid and jasmonic acid-isoleucine levels in the roots. Plant Signaling & Behavior 2013, 8, e26301 .
AMA StyleKhabat Vahabi, Iris Camehl, Irena Sherameti, Ralf Oelmüller. Growth ofArabidopsisseedlings on high fungal doses ofPiriformospora indicahas little effect on plant performance, stress, and defense gene expression in spite of elevated jasmonic acid and jasmonic acid-isoleucine levels in the roots. Plant Signaling & Behavior. 2013; 8 (11):e26301.
Chicago/Turabian StyleKhabat Vahabi; Iris Camehl; Irena Sherameti; Ralf Oelmüller. 2013. "Growth ofArabidopsisseedlings on high fungal doses ofPiriformospora indicahas little effect on plant performance, stress, and defense gene expression in spite of elevated jasmonic acid and jasmonic acid-isoleucine levels in the roots." Plant Signaling & Behavior 8, no. 11: e26301.
The mutualistic interaction between the endophytic and root-colonizing fungus and is a nice model system to study beneficial and non-benefical traits in a symbiosis. Colonized Arabidopsis plants are taller, produce more seeds and are more resistant against biotic and abiotic stress. Based on genetic, molecular and cellular analyses, Arabidopsis mutants were identified which are impaired in their beneficial response to the fungus. Several mutants are smaller rather than bigger in the presence of the fungus and are defective in defense responses. This includes mutants with defects in defense-signaling components, defense proteins and enzymes, and defense metabolites. The mutants cannot control root colonization and are often over-colonized by . As a consequence, the benefits for the plants are lost and they try to restrict root colonization by activating unspecific defense responses against . These observations raise the question as to how the plants balance defense gene activation or development and what signaling molecules are involved. promotes the synthesis of phosphatidic acid (PA), which binds to the 3-PHOSPHOINOSITIDE-DEPENDENT-KINASE1 (PDK1). This activates a kinase pathway which might be crucial for balancing defense and growth responses. The review describes plant defense compounds which are necessary for the mutualistic interaction between the two symbionts. Furthermore, it is proposed that the PA/PDK1 pathway may be crucial for balancing defense responses and growth stimulation during the interaction with .
Pyniarlang L. Nongbri; Khabat Vahabi; Anna Mrozinska; Eileen Seebald; Chao Sun; Irena Sherameti; J. Michal Johnson; Ralf Oelmüller. Balancing defense and growth—Analyses of the beneficial symbiosis between Piriformospora indica and Arabidopsis thaliana. Symbiosis 2012, 58, 17 -28.
AMA StylePyniarlang L. Nongbri, Khabat Vahabi, Anna Mrozinska, Eileen Seebald, Chao Sun, Irena Sherameti, J. Michal Johnson, Ralf Oelmüller. Balancing defense and growth—Analyses of the beneficial symbiosis between Piriformospora indica and Arabidopsis thaliana. Symbiosis. 2012; 58 (1):17-28.
Chicago/Turabian StylePyniarlang L. Nongbri; Khabat Vahabi; Anna Mrozinska; Eileen Seebald; Chao Sun; Irena Sherameti; J. Michal Johnson; Ralf Oelmüller. 2012. "Balancing defense and growth—Analyses of the beneficial symbiosis between Piriformospora indica and Arabidopsis thaliana." Symbiosis 58, no. 1: 17-28.
The introduction of molecular oxygen into the atmosphere was accompanied by the generation of reactive oxygen species (ROS) as side products of many biochemical reactions. ROS are permanently generated in plastids, peroxisomes, mitochiondria, the cytosol and the apoplast. Imbalance between ROS generation and safe detoxification generates oxidative stress and the accumulating ROS are harmful for the plants. On the other hand, specific ROS function as signaling molecules and activate signal transduction processes in response to various stresses. Here, we summarize the generation of ROS in the different cellular compartments and the signaling processes which are induced by ROS.
Baishnab Charan Tripathy; Ralf Oelmüller. Reactive oxygen species generation and signaling in plants. Plant Signaling & Behavior 2012, 7, 1621 -1633.
AMA StyleBaishnab Charan Tripathy, Ralf Oelmüller. Reactive oxygen species generation and signaling in plants. Plant Signaling & Behavior. 2012; 7 (12):1621-1633.
Chicago/Turabian StyleBaishnab Charan Tripathy; Ralf Oelmüller. 2012. "Reactive oxygen species generation and signaling in plants." Plant Signaling & Behavior 7, no. 12: 1621-1633.