Ralf Oelmüller

• Friedrich Schiller University Jena

Orchid mycorrhizal (OM) fungi form mutualistic relationships with orchids, facilitating the uptake of minerals from the soil in exchange for sugars and lipids provided by the plant. In this study, we explored the role of the DoSWEET14 sugar transporter in Dendrobium officinale during OM symbiosis. Transcriptome sequencing revealed significant chang...

This study focuses on the question how and where information acquired by FLS2 perception of flg22 is transformed into electrical signals crucial for generation of local and systemic defense responses. In Arabidopsis thaliana and Vicia faba leaves, FLS2 density was high in the epidermis and vascular parenchyma, low in mesophyll, and absent in sieve...

The Fusarium incarnatum strain K23, originally isolated from a habit-adapted wild plant Thapsia species, colonized on the roots and shoots of tomato seedlings and protected them against salt stress. K23 produces gibberellin, and the activation of gibberellin-responsive genes were detected in control and salt-stressed seedlings. Interestingly, compa...

Soil salinity is a significant abiotic stress factor that impedes plant growth and crop yield, particularly in arid and semi-arid regions. Recent reports indicate that 8.7% of soils globally and 20–50% of irrigated soils across all continents are affected by salt. This phenomenon jeopardizes the food security of more than 1.5 billion people worldwi...

Plants share their habitats with a multitude of different microbes. This close vicinity promoted the evolution of interorganismic interactions between plants and many different microorganisms that provide mutual growth benefits both to the plant and the microbial partner. The symbiosis of Arabidopsis thaliana with the beneficial root colonizing end...

Plants share their habitats with a multitude of different microbes. This close vicinity promoted the evolution of inter-organismic interactions between plants and many different microorganisms that provide mutual growth benefits both to the plant and the microbial partner. The symbiosis of Arabidopsis thaliana with the beneficial root colonizing en...

The degradation of cellulose generates cellooligomers, which function as damage-associated molecular patterns and activate immune and cell wall repair responses via the CELLOOLIGOMER RECEPTOR KINASE1 (CORK1). The most active cellooligomer for the induction of downstream responses is cellotriose, while cellobiose is around 100 times less effective....

Systemic acquired resistance protects plants against a broad spectrum of secondary infections by pathogens. A crucial compound involved in the systemic spread of the threat information after primary pathogen infection is the C9 oxylipin azelaic acid (AZA), a breakdown product of unsaturated C18 fatty acids. AZA is generated during lipid peroxidatio...

Plants share their habitats with a multitude of different microbes. This close vicinity promoted the evolution of inter-organismic interactions between plants and many different microorganisms that provide mutual growth benefits both to the plant and the microbial partner. The symbiosis of Arabidopsis thaliana with the beneficial root colonizing en...

Non-mycorrhizal but beneficial fungi often mitigate (a)biotic stress-related traits in host plants. The underlying molecular mechanisms are mostly still unknown, as in the interaction between the endophytic growth-promoting soil fungus Mortierella hyalina and Arabidopsis thaliana. Here, abiotic stress in the form of nitrogen (N) deficiency was used...

We identified, isolated and functionally characterized, cyclin dependent kinase (CDK), PiPho85 from Piriformospora indica. The identified PiPho85 contains TY, PSTAIRE, protein kinase domain, and an ATP binding site which is highly conserved amongst the Pho85/CDK5 family protein specific for Pho85 of Saccharomyces cerevisiae. In ( Δpho85 ) mutant st...

The root-colonizing endophytic fungus Piriformospora indica promotes the root and shoot growth of its host plants. We show that the growth promotion of Arabidopsis thaliana leaves is abolished when the seedlings are grown on media with nitrogen (N) limitation. The fungus neither stimulated the total N content nor did it promote ¹⁵NO3⁻ uptake from a...

The productivity of plants is hindered by unfavorable conditions. To perceive stress signals and to transduce these signals to intracellular responses, plants rely on membrane-bound receptor-like kinases (RLKs). These play a pivotal role in signaling events governing growth, reproduction, hormone perception, and defense responses against biotic str...

The root-colonizing endophytic fungus Piriformospora indica promotes root and shoot growth of its host plants. We show that growth promotion of Arabidopsis leaves is abolished when the seedlings are grown on media with nitrogen (N) limitation. The fungus neither stimulated the total N content nor did it promote 15NO3- uptake from agar plates to the...

Progestogens and androgens have been found in many plants, but little is known about their biosynthesis and the evolution of steroidogenesis in these organisms. Here, we show that the occurrence and biosynthesis of progestogens and androgens are conserved across the viridiplantae lineage. An UHPLC‐ESI‐MS/MS method allowed high‐throughput analysis o...

The Indo-German Science and Technology Centre (IGSTC) funded an Indo-German Workshop on Sustainable Stress Management: Aquatic plants vs. Terrestrial plants (IGW-SSMAT) which was jointly organized at the Friedrich Schiller University of Jena, Germany from 25 to 27 July 2022 by Prof. Dr. Ralf Oelmüller, Friedrich Schiller University of Jena, Germany...

Kenya is the seventh most prominent producer of common beans globally and the second leading producer in East Africa. However, the annual national productivity is low due to insufficient quantities of vital nutrients and nitrogen in the soils. Rhizobia are symbiotic bacteria that fix nitrogen through their interaction with leguminous plants. Nevert...

The integrity of the cell wall is important for plant cells. Mechanical or chemical distortions, tension, pH changes in the apoplast, disturbance of the ion homeostasis, leakage of cell compounds into the apoplastic space or breakdown of cell wall polysaccharides activate cellular responses which often occur via plasma membrane-localized receptors....

We have recently demonstrated that the cellulose breakdown product cellotriose is a damage-associated molecular pattern (DAMP) which induces responses related to the integrity of the cell wall. Activation of downstream responses requires the Arabidopsis malectin domain-containing CELLOOLIGOMER RECEPTOR KINASE1 (CORK1)¹. The cellotriose/CORK1 pathwa...

Rhizobia are soil bacteria that induce nodule formation on leguminous plants. In the nodules, they reduce dinitrogen to ammonium that can be utilized by plants. Besides nitrogen fixation, rhizobia have other symbiotic functions in plants including phosphorus and iron mobilization and protection of the plants against various abiotic stresses includi...

Drought challenges crop production worldwide. The issue is aggravated by frequent drought episodes and unpredictable rainfall patterns associated with global climate change. While the efforts to breed drought-resistant crop varieties are progressing, the need of the hour is immediate strategies to sustain the yields of existing ones. As per recent...

The dark-detached leaves are widely used as a model to investigate senescence-delaying mechanisms of cytokinin (CК). The role of CK during senescence of detached Arabidopsis leaves in the light is less examined, although they provide unique opportunities for the study of the interaction of CK and the photosynthetic apparatus. Within the first four...

Cell wall integrity (CWI) maintenance is central for plant cells. Mechanical and chemical distortions, pH changes, and breakdown products of cell wall polysaccharides activate plasma membrane-localized receptors and induce appropriate downstream responses. Microbial interactions alter or destroy the structure of the plant cell wall, connecting CWI...

Microbial volatiles are important factors in symbiotic interactions with plants. Mortierella hyalina is a beneficial root-colonizing fungus with a garlic-like smell, and promotes growth of Arabidopsis seedlings. GC–MS analysis of the M. hyalina headspace and NMR analysis of the extracted essential oil identified the sulfur-containing volatile tris(...

Calcium is an important second messenger in plants. The activation of Ca2+ signaling cascades is critical in the activation of adaptive processes in response to environmental stimuli. Root colonization by the growth promoting endophyte Serendipita indica involves the increase of cytosolic Ca2+ levels in Arabidopsis thaliana. Here, we investigated t...

In the wake of changing climatic conditions, plants are frequently exposed to a wide range of biotic and abiotic stresses at various stages of their development, all of which negatively affect their growth, development, and productivity. Drought is one of the most devastating abiotic stresses for most cultivated crops, particularly in arid and semi...

Key message Calmodulin-like-proteins (CML) belong to a family of calcium-sensing proteins that are unique for plants and involved in many different developmental and stress-related reactions. In defense against herbivory, some pathogens and drought, CML37 acts as a positive and CML42 as a negative regulator, respectively. We provide evidence that b...

Plant surfaces are covered with cuticle wax and are the first barrier between a plant and environmental stresses. Eceriferum (CER) is an important gene family involved in wax biosynthesis and stress resistance. In this study, for the first time, 34 CER genes were identified in the passion fruit (Passiflora edulis) genome, and PeCER proteins varied...

Grain legumes play a significant role in smallholder farming systems in Africa because of their contribution to nutrition and income security and their role in fixing nitrogen. Biological Nitrogen Fixation (BNF) serves a critical role in improving soil fertility for legumes. Although much research has been conducted on rhizobia in nitrogen fixation...

Calcium (Ca ) is an important second messenger in plants. The activation of Ca signaling cascades is critical in the activation of adaptive processes in response to perceived environmental stimuli, including biotic stresses. The colonization of roots by the plant growth promoting endophyte Serendipita indica involves the increase of cytosolic Ca le...

Cell wall integrity (CWI) maintenance is central for plant cells. Mechanical or chemical distortions, pH changes, or breakdown products of cell wall polysaccharides activate plasma membrane-localized receptors and induce appropriate downstream responses. Microbial interactions alter or destroy the structure of the plant cell wall, connecting CWI ma...

Plant and fruit surfaces are covered with cuticle wax and provide a protective barrier against biotic and abiotic stresses. Cuticle wax consists of very-long-chain fatty acids (VLCFAs) and their derivatives. β-Ketoacyl-CoA synthase (KCS) is a key enzyme in the synthesis of VLCFAs and provides a precursor for the synthesis of cuticle wax, but the KC...

Soils with low pH and high aluminium (Al) contamination restrict common bean production, mainly due to adverse effects on rhizobia. We isolated a novel rhizobium strain, B3, from Kenyan soil which is more tolerant to Al stress than the widely used commercial strain CIAT899. B3 was resistant to 50 µM Al and recovered from 100 µM Al stress, while CIA...

The dark-detached leaves are widely used as a model to investigate senescence-delaying mechanisms of cytokinin (СК). The role of CK during senescence of detached Arabidopsis leaves in the light is less examined, although they provide unique opportunities for the study of the interaction of CK and the photosynthetic apparatus. Within the first four...

Numerous Trichoderma strains are beneficial for plants, promote their growth, and confer stress tolerance. A recently described novel Trichoderma strain strongly promotes the growth of Arabidopsis thaliana seedlings on media with 50 mM NaCl, while 150 mM NaCl strongly stimulated root colonization and induced salt-stress tolerance in the host withou...

Passion fruit (Passiflora edulis) is an important fruit crop with high economic value. Genetic engineering plays an important role in crop improvement with desired traits and gene functional studies. The lack of a simple, efficient, and stable transformation system for passion fruit has greatly limited gene functional studies. In this study, a simp...

Citation: Rizwan, H.M.; Yang, Q.; Yousef, A.F.; Zhang, X.; Sharif, Y.; Kaijie, J.; Shi, M.; Li, H.; Munir, N.; Yang, X.; et al. Establishment of a Novel and Efficient Agrobacterium-Mediated in Planta

Due to progress in the industrial development of light-emitting diodes (LEDs), much work has been dedicated to understanding the reaction of plants to these light sources in recent years. In this study, the effect of different LED-based light regimes on growth and performance of passion fruit (Passiflora edulis) seedlings was investigated. Combinat...

Production of passion fruit (Passiflora edulis) is restricted by postharvest decay, which limits the storage period. We isolated, identified, and characterized fungal pathogens causing decay in two passion fruit cultivars during two fruit seasons in China. Morphological characteristics and nucleotide sequences of ITS-rDNA regions identified eightee...

Common bean is one of the primary protein sources in third-world countries. They form nodules with nitrogen-fixing rhizobia, which have to be adapted to the local soils. Commercial rhizobial strains such as Rhizobium tropici CIAT899 are often used in agriculture. However, this strain failed to significantly increase the common bean yield in many pl...

Microbial volatiles are important factors in symbiotic interactions with plants. Mortierella hyalina is a beneficial root-colonizing fungus with a garlic-like smell, and promotes growth of Arabidopsis seedlings. GC-MS analysis of the M. hyalina headspace and NMR analysis of the extracted essential oil identified the sulfur-containing volatile tris(...

Microbial volatiles are important factors in symbiotic interactions with plants. Mortierella hyalina is a beneficial root-colonizing fungus with a garlic-like smell, and promotes growth of Arabidopsis seedlings. GC-MS analysis of the M. hyalina headspace and NMR analysis of the extracted essential oil identified the sulfur-containing volatile tris(...

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 an...

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 plant...

Napier grass stunt (NGS) phytoplasma, a phloem-limited bacterium, infects Napier grass leading to severe yield losses in East Africa. The infected plants are strongly inhibited in growth and biomass production. In this study, phytoplasma-induced morphological changes of the vascular system and physiological changes were analyzed and compared with u...

Cellular calcium (Ca) transients are endogenous signals involved in local and systemic signaling and defense activation upon environmental stress, including wounding and herbivory. Still, not all Ca²⁺ channels contributing to the signaling have been identified, nor are their modes of action fully known. Plant annexins are proteins capable of bindin...

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...

Passion fruit (Passiflora edulis) has an important economic value as exotic ingredient in juice blends. We inoculated the passion fruit cultivar Passiflora edulis Sims f. edulis’s roots with the beneficial root-colonizing fungus Piriformospora indica under greenhouse conditions. The experiments were performed at three different locations and times...

Freezing stress is a serious environmental factor that obstructs plant development. The root endophytic fungus Piriformospora indica has proved to be effective to confer abiotic stress tolerance to host plants. To investigate how P. indica improves freezing tolerance, we compared the expression profiles of P. indica-colonized and uncolonized Arabid...

Plants host numerous endophytic microbes which promote plant performance, in particular under stress. A new endophytic fungus was isolated from the leaves of a deciduous wood tree Leucas aspera. Morphological inspection and multilocus phylogeny identified the fungus as a new Trichoderma strain. If applied to Arabidopsis thaliana and Nicotiana atten...

Endophytes are non-disease causing microbes (bacteria and fungi) surviving in living tissues of plants. Their intimate association and possible coevolution with their plant partners have resulted in them contributing to an array of plant growth benefits ranging from enhanced growth and biomass accumulation, tolerance to abiotic and biotic stresses...

The root endophytic fungus Piriformospora indica plays an important role in increasing abiotic stress tolerance of its host plants. To explore the impact of P. indica on freezing tolerance, Arabidopsis seedlings were co-cultivated with P. indica exposed to −6°C for 6 h. Freezing stress decreased the survival rate, electrolyte leakage, leaf temperat...

Endophytes, both of bacterial and fungal origin, are ubiquitously present in all plants. While their origin and evolution are enigmatic, there is burgeoning literature on their role in promoting growth and stress responses in their hosts. We demonstrate that a salt-tolerant endophyte isolated from salt-adapted Pokkali rice, a Fusarium sp., colonize...

Global water shortage seriously threatens rice growth especially in irrigated production areas. Association of plants with beneficial soil microbes is one strategy for plant adaption to environmental stresses. In this study, rice (Oryza sativa L.) plants were colonized by the beneficial root-colonizing endophytic fungus Piriformospora indica (P. in...

The global climate change is arguably one of the biggest threats of our times that already led to a wide range of impacts on the environment, economy, and society. Due to past emissions and the inertia of the climate system, global climate change is estimated to continue for decades even though anthropogenic greenhouse gas emissions could be stoppe...

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...

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 a...

DNA and the machinery for gene expression have been discovered in chloroplasts during the 1960s. It was soon evident that the chloroplast genome is small, that many genes for chloroplast-localized proteins must reside in the nucleus, and that the expression of the genes in both cellular compartments must be coordinated. In the 1970s, the first evid...

Phytohormones are crucial molecules for plant development and the interaction with microbes. This study focused on the phytohormone auxin (indole-3-acetic acid, IAA) and its role in the interaction of Arabidopsis thaliana (L.) Heynh. roots with two beneficial (Piriformospora indica and Mortierella hyalina) and two pathogenic (Alternaria brassicicol...

Piriformospora indica, an endophytic fungus of Sebacinales, has a wide host range and promotes the performance of mono- and eudicot plants. Here, we compare the interaction of P. indica with the roots of seven host plants (Anthurium andraeanum, Arabidopsis thaliana, Brassica campestris, Lycopersicon esculentum, Oncidium orchid, Oryza sativa, and Ze...

Auxin (indole-3-acetic acid, IAA) is an important phytohormone involved in root growth and development. Root-interacting beneficial and pathogenic fungi utilize auxin and its target genes to manipulate the performance of their hosts for their own needs. In order to follow and visualize auxin effects in fungi-colonized Arabidopsis roots, we used the...

Visualization of auxin maxima using the reporter construct DR5::EGFP-DR5v2::tdTomato during plant-fungus interaction. Light sheet videos of 17 h-recordings of control without addition of fungal spores.

Visualization of auxin maxima using the reporter construct DR5::EGFP-DR5v2::tdTomato during plant-fungus interaction. Light sheet video of 17 h-recording of co-cultivation with P. indica spore solution.

Visualization of auxin maxima using the reporter construct DR5::EGFP-DR5v2::tdTomato during plant-fungus interaction. Light sheet video of 17 h-recording of co-cultivation with M. hyalina spore solution. Background fluorescence in M. hyalina co-culture is due to autofluorescence of spores.

Visualization of auxin maxima using the reporter construct DR5::EGFP-DR5v2::tdTomato during plant-fungus interaction. Light sheet video of 17 h-recording of co-cultivation with A. brassicicola spore solution.

Visualization of auxin maxima using the reporter construct DR5::EGFP-DR5v2::tdTomato during plant-fungus interaction. Light sheet video of 17 h-recording of co-cultivation with V. dahliae spore solution.

Background Anthurium andraeanum, an important ornamental flower, has to go through a growth-delaying period after transfer from tissue culture to soil, which requires time and extra costs. Furthermore, during this period, the plantlets are highly susceptible to bacterial infections, which results in impaired development and severe losses. Here, we...

Effector proteins play important roles in the infection by pathogenic oomycetes and fungi or the colonization by endophytic and mycorrhizal fungi. They are either translocated into the host plant cells via specific translocation mechanisms and function in the host's cytoplasm or nucleus, or they reside in the apoplast of the plant cells and act at...

Plants interact with a wide variety of fungi in a mutualistic, parasitic or neutral way. The associations formed depend on the exchange of nutrients and signalling molecules between the partners. This includes a diverse set of protein classes involved in defence, nutrient uptake or establishing a symbiotic relationship. Here, we have analysed the s...

List of primers used in this study. (XLSX)

Expression analyses of genes associated with the scopolin pathway. Expression of PYK10 and other key genes of the scopolin pathway in roots of WT and F6’H1 at 7 dpi (A) and 14 dpi (B). Error bars represent standard deviation calculated from four biological replicates. The asterisks shows the significant difference, as described in Fig 3A. (TIF)

Measurement of ER-body size at 3 dpi in liquid media and in solid media. Comparison of the ER-body length in Arabidopsis root cells without and with P. indica at 3 dpi. Liquid cultivation method from the secretome measurement was compared with the standard solid cultivation method. Error bars represents standard deviation. Different letters represe...

Overview of secretomes and Expression analyses of plat genes. (A) Venn diagram of A. thaliana proteins found in three replicates in the co-culture (generated with http://bioinformatics.psb.ugent.be/webtools/Venn/). (B) Profile for plat2 expression in WT roots and leaves. (C) Profile for plat3 expression in WT roots and leaves. For plat3, CT values...

List of proteins enriched across all three secretomes. Identified proteins were considered differentially enriched, when they were found in at least two replicates in one treatment and not in the other treatment. Furthermore, proteins that were found with a high frequency in one treatment and with a low frequency in the other treatment, were consid...

List of proteins identified in the secretomes from single and co-cultures. Selected proteins were identified by at least two unique peptides and a false discovery rate of <1%. The frequency of occurrence is given as Low (1 out of 3), Medium (2 out of 3) or High (3 out of 3 replicates) based on the frequency of detection in all replicates. (XLSX)

Colonisation of A. thaliana by P. indica in liquid media at 3 dpi. Arabidopsis roots in liquid (A) and solid media (B) were imaged using fluorescence microscopy. In both cultures, only little fungus was found in and around the root. The first pictures show the autofluorescence of the root and GFP fluorescence of P. indica. The second pictures show...

Microscopy of ER-Bodies at 3 dpi in liquid media and in solid media. Fluorescence microscopy of ER-bodies in roots without and with P. indica. Liquid cultivation method from the secretome measurement was compared with the standard solid cultivation method. Mock treatment in liquid culture (A) and in solid culture (B) and colonised roots at 3 dpi in...

Aims The root endophytic fungus Piriformospora indica (P. indica) colonizes the roots of a wide range of higher plants and promotes growth, disease resistance and stress tolerance of the hosts. We investigated the role of P. indica for phosphate (P) mobilization in soils enriched with different P sources and for P uptake into Brassicae napus (B. na...

The endophytic fungus Mortierella hyalina colonizes the roots of Arabidopsis thaliana and stimulates growth and biomass production of the aerial parts, but not of roots. An exudate fraction from the fungus induces rapid and transient cytoplasmic Ca2+elevation in the roots. The Ca2+ response does not require the well-characterized (co-)receptors BAK...

Phytohormones play vital roles in the growth and development of plants as well as in interactions of plants with microbes such as endophytic fungi. The endophytic root-colonizing fungus Piriformospora indica promotes plant growth and performance, increases resistance of colonized plants to pathogens, insects and abiotic stress. Here, we discuss the...

Calcium is an important second messenger in plants that is released into the cytosol early after recognition of various environmental stimuli. Decoding of such calcium signals by calcium sensors is the key for the plant to react appropriately to each stimulus. Several members of Calmodulin-like proteins (CMLs) act as calcium sensors and some are kn...

Verification of cml9-a and cml9-b. Semi quantitative RT-PCR analysis of CML9 full transcript expression in wild type and knock-out mutants after 30 min of MecWorm treatment. Expression of ACTIN2 was used as quantitative control. Water was used as negative control. The expected product length is written on the right sites of the respective pictures....

Primers used for different PCRs. (DOCX)