Fungal peroxygenases represent an exciting new enzyme class for stereo-selective hydroxylation reactions. They are capable of the oxyfunctionalisation of a large, diverse scope of substrates including alkanes and steroids as well as the heteroatoms sulfur and nitrogen. The outstanding activities and stabilities as well as their reliance on hydrogen peroxide as co-substrate renders it a highly interesting biocatalyst.

Benzylisoquinoline alkaloids (BIAs) are important secondary plant metabolites and include medicinally relevant drugs, such as morphine or codeine. As the de novo synthesis of BIA backbones is (still) unfeasible, to date the opium poppy plant Papaver somniferum L. represents the main source of BIAs. The formation of BIAs is induced in poppy plants by stress conditions, such as wounding or salt treatment; however, the details about regulatory processes controlling BIA formation in opium poppy are not well studied. Environmental stresses, such as wounding or salinization, are transduced in plants by phospholipid-based signaling pathways, which involve different classes of phospholipases. Here we investigate whether pharmacological inhibition of phospholipase A2 (PLA2, inhibited by aristolochic acid (AA)) or phospholipase D (PLD; inhibited by 5-fluoro-2-indolyl des-chlorohalopemide (FIPI)) in poppy plants influences wound-induced BIA accumulation and the expression of key biosynthetic genes. We show that inhibition of PLA2 results in increased morphinan biosynthesis concomitant with reduced production of BIAs of the papaverine branch, whereas inhibition of PLD results in increased production of BIAs of the noscapine branch. The data suggest that phospholipid-dependent signaling pathways contribute to the activation of morphine biosynthesis at the expense of the production of other BIAs in poppy plants. A better understanding of the effectors and the principles of regulation of alkaloid biosynthesis might be the basis for the future genetic modification of opium poppy to optimize BIA production.

Drought is one of the most important environmental stressors resulting in increasing losses of crop plant productivity all over the world. Therefore, development of new approaches to increase the stress tolerance of crop plants is strongly desired. This requires precise and adequate modeling of drought stress. As this type of stress manifests itself as a steady decrease in the substrate water potential (ψw), agar plates infused with polyethylene glycol (PEG) are the perfect experimental tool: they are easy in preparation and provide a constantly reduced ψw, which is not possible in soil models. However, currently, this model is applicable only to seedlings and cannot be used for evaluation of stress responses in mature plants, which are obviously the most appropriate objects for drought tolerance research. To overcome this limitation, here we introduce a PEG-based agar infusion model suitable for 6–8-week-old A. thaliana plants, and characterize, to the best of our knowledge for the first time, the early drought stress responses of adult plants grown on PEG-infused agar. We describe essential alterations in the primary metabolome (sugars and related compounds, amino acids and polyamines) accompanied by qualitative and quantitative changes in protein patterns: up to 87 unique stress-related proteins were annotated under drought stress conditions, whereas further 84 proteins showed a change in abundance. The obtained proteome patterns differed slightly from those reported for seedlings and soil-based models.

The screening effort of large protein variant libraries renders the probability of coincidental discovering a new enzyme with non-natural activity to almost zero - the so-called numbers problem. Insights into the origin of life, evolution and enzymatic promiscuity, combined with the inspiration of methods from organic chemistry, offer solutions for this problem. With the newly discovered enzymes synthetic micro production units shall be established in a Leibniz Research Cluster where engineering and biotechnology are combined.

Drought, salinity and alkalinity are distinct forms of osmotic stress with serious impacts on rice productivity. We investigated, for a salt-sensitive rice cultivar, the response to osmotically equivalent doses of these stresses. Drought, experimentally mimicked by mannitol (single factor: osmotic stress), salinity (two factors: osmotic stress and ion toxicity), and alkalinity (three factors: osmotic stress, ion toxicity, and depletion of nutrients and protons) produced different profiles of adaptive and damage responses, both locally (in the root) as well as systemically (in the shoot). The combination of several stress factors was not necessarily additive, and we even observed cases of mitigation, when two (salinity), or three stressors (alkalinity) were compared to the single stressor (drought). The response to combinations of individual stress factors is therefore not a mere addition of the partial stress responses, but rather represents a new quality of response. We interpret this finding in a model, where the output to signaling molecules is not determined by their abundance per se, but qualitatively depends on their adequate integration into an adaptive signaling network. This output generates a systemic signal that will determine the quality of the shoot response to local concentrations of ions.

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As a result of the phenylpropanoid pathway, many Brassicaceae produce considerable amounts of soluble hydroxycinnamate conjugates, mainly sinapate esters. From oilseed rape (Brassica napus), we cloned two orthologs of the Arabidopsis (Arabidopsis thaliana) gene REDUCED EPIDERMAL FLUORESCENCE1 (REF1) encoding a coniferaldehyde/sinapaldehyde dehydrogenase. The enzyme is involved in the formation of ferulate and sinapate from the corresponding aldehydes, thereby linking lignin and hydroxycinnamate biosynthesis as a potential branch-point enzyme. We used RNA interference to silence REF1 genes in seeds of oilseed rape. Nontargeted metabolite profiling showed that BnREF1-suppressing seeds produced a novel chemotype characterized by reduced levels of sinapate esters, the appearance of conjugated monolignols, dilignols, and trilignols, altered accumulation patterns of kaempferol glycosides, and changes in minor conjugates of caffeate, ferulate, and 5-hydroxyferulate. BnREF1 suppression affected the level of minor sinapate conjugates more severely than that of the major component sinapine. Mapping of the changed metabolites onto the phenylpropanoid metabolic network revealed partial redirection of metabolic sequences as a major impact of BnREF1 suppression.

Late stage enzymatic prenylation and methylation are means to diversify (natural) compounds and to specify their functions. In eukaryotes and microbes, these steps are performed by large enzyme families, the prenyl and methyl transferases, which modify various types of small molecules, like isoprenoids, phenolics or alkaloids, but also DNA and proteins. We investigate the theoretical basis of these processes and possible commercial applications in synthetic chemistry.

In phytopathology quantitative measurements are rarely used to assess crop plant disease symptoms. Instead, a qualitative valuation by eye is often the method of choice. In order to close the gap between subjective human inspection and objective quantitative results, the development of an automated analysis system that is capable of recognizing and characterizing the growth patterns of fungal hyphae in micrograph images was developed. This system should enable the efficient screening of different host–pathogen combinations (e.g., barley—Blumeria graminis, barley—Rhynchosporium secalis) using different microscopy technologies (e.g., bright field, fluorescence). An image segmentation algorithm was developed for gray-scale image data that achieved good results with several microscope imaging protocols. Furthermore, adaptability towards different host–pathogen systems was obtained by using a classification that is based on a genetic algorithm. The developed software system was named HyphArea, since the quantification of the area covered by a hyphal colony is the basic task and prerequisite for all further morphological and statistical analyses in this context. By means of a typical use case the utilization and basic properties of HyphArea could be demonstrated. It was possible to detect statistically significant differences between the growth of an R. secalis wild-type strain and a virulence mutant.

Fungi cause severe diseases on a broad range of crop and ornamental plants, leading to significant economical losses. Plant pathogenic fungi exhibit a huge variability in their mode of infection, differentiation and function of infection structures and nutritional strategy. In this review, advances in understanding mechanisms of biotrophy, necrotrophy and hemibiotrophic lifestyles are described. Special emphasis is given to the biotrophy-necrotrophy switch of hemibiotrophic pathogens, and to biosynthesis, chemical diversity and mode of action of various fungal toxins produced during the infection process.