Most losses in agriculture are not caused by pests and diseases, but some 80% are caused by drought and – to a much minor extent - other forms of abiotic stress (excess of frost, UV, heat, salt, or minerals deficits). We aim to enhance the plants tolerance to these environmental factors by non-GMO methods, which are applicable in a spatially and time controlled manner. Plant protectants used for induced adaptive modifications of plants are termed phytoeffectors and ideally act independently of the crop species and variety used, i.e. the farmer is not limited in his choice of supplier and can use home grown seeds or a wide variety of genetic and commercial resources.

In general, drought is accompanied with metabolic adjustment, i.e. accumulation of drought-protective proteins and metabolites, in parallel to the development of oxidative stress. The plant uses much of its energy resources for this adaptation and to ensure a next generation, e.g., by going into emergency maturation instead of waiting for better times. Drought tolerance is usually understood as the plant physiological state allowing preservation of crop productivity despite unfavorable osmotic conditions. In this context, tolerant crop plants are expected to keep or regain their productivity and nutritional value under such adverse conditions. This can be achieved by application of drought-protective phytoeffectors, typically representing inhibitors of drought-responsive enzymes, the key-players of the plant stress response (for a review see: Int. J. Mol. Sci. 2018). Thus, the main aims of the project group are:

• development of adequate models and assays for the characterization of plant stress responses,
• characterization of deletirious aspects of drought stress or fertilizer (urea) uptake responses affecting plant productivity,
• identification of prospective targets for the application of a phytoeffector approach,
• search for new potent phytoeffectors,
• SAR and ADM(T) properties of plant protectants, with design and synthesis of improved phytoeffectors.

A recently concluded flagship project "Beeinflussung biologischer Prozesse mit Small Molecules – ein neuartiger Ansatz in der Pflanzenernährungsforschung zur Verbesserung der Stickstoff-Effizienz" can be found here. This is a collaborative research project under the roof of the Agrochemical Institute Piesteritz e.V., supported by EFRE and the Ministry of Science and Economy of the state Saxony-Anhalt , the Stickstoffwerke company SKW Piesteritz , and the Leibniz ScienceCampus "Plant Based BioEconomy".

Project Phytoeffectors:

Development of new phytoeffectors reducing drought stress
 

Chemoinformatic and biochemical methods are employed to combine data from different resources (like literature, gene expression and proteomics), find new target proteins, perform in silico screening with our structure databases and test the found ligands in different in vivo assays. Beneath drought stress we are interested in bacterial proteins of the nitrogen metabolism that interfere with the nitrogen supply of plants. We use 3D structures (crystal structures or homology models) of such proteins to investigate their catalytic mechanism by means of quantum chemistry and derive information for inhibitor design.

To address potential phytoeffector effect of synthetic substances, we use two drought models.

1. Our Lemna minor test system (Geissler and Wessjohann, J. Plant Growth Regul. 2011) is currently employed on a routine basis in the department. Compared to commonly used spraying assays, it the first drought stress assay in microtiter plates, with small volumes and absolute control of concentrations and thus applied amount of compound, simultaneous root and shoot application, clones (budding) microplants and an easy readout (leaf surface area and color).

After culture in an aqueous medium (Fig. 1a), individual Lemna plantlets of the same stage are transferred to 24-well plates (Fig. 1b) with the test substances in the growth medium in a start concentration of usually 10 µmol/L and a dilution series. The drought stress is applied for, e.g., 48 h by the addition of the growth medium containing 150 g/L Polyethylenglycol PEG 6000, and the total leaf area is assessed 24 h later with a LemnaTec Scanalyzer (Fig. 1c). During the past years several hundred substances representing ten focus structure classes were analyzed.

2. Arabidopsis thaliana is the plant researchers most relevant model plant and a relative of commercial rape. A test system for these plants was established in 2017 (Frolov et al. J. Plant Physiol. 2017). It relies on the agar-based PEG infusion model, earlier proposed for seedlings by Verslues et al. (2006). We extended this approach to mature plants, usually suffering in fields from moderate transient drought, and performed complete characterization with a pattern of biochemical, transcriptional and physiological markers (Paudel et al., J. Exp. Bot. 2016). The plants are grown for six weeks in aqueous medium prior to the stress application by transfer to agar, saturated with PEG8000 solution during three days.