Research

Amino acids, peptides and proteins as a source of nitrogen

Nitrogen (N) is one of the key factors regulating plant growth and development. Despite of plant mineral nutrition being a well-studied topic, organic-bound N as a source of N for plants has only recently attracted deserved attention as a part of sustainable agriculture and environmental protection. Soil contains many forms of organic N such as amino acids, nucleotides, and their polymers including proteins. Still only little is known about the ways which plants could use to acquire N from these organic resources.

Biological control agents

The management of certain plant beneficial microorganisms, so to speak "biological control agents", seems to be a promising and environmental friendly method to control plant pathogens. These agents include fungi, oomycetes or bacteria, and their positive effect seems to originate in interactions that prime plant’s defense responses and enhance plant resistance to future stressors. The degree of disease suppression achieved with biological agents can even be comparable to that achieved with chemicals.

Antioxidant capacity

During the evolution plants have developed rather efficient mechanisms for the removal of harmful compounds, which include e. g. the reactive oxygen species (ROS). These mechanisms are mainly based on the antioxidant effects of ascorbic acid, glutathione in intimate cooperation with superoxide dismutase, catalase and various peroxidases – the reduced coenzymes, NADH and NADPH, play a major role in the ROS elimination, too. However, in recent times, the attention has turned from these key compounds of primary metabolism to secondary metabolites. Interestingly, phenolic compounds together with some terpenes and alkaloids exhibit antioxidant effects, too, and apparently they play an irreplaceable role in the life of plants – besides their antioxidant action they are also important in the fight against pathogens and herbivores, in attracting the pollinators or in the moderation of UV light effects. Natural products are also studied in their relation to human – a broad variety of effects is known including the antioxidant, anti-inflammatory and anticancer effects for the most part.

Shikimate dehydrogenase

In plants the shikimate pathway followed by the phenylpropanoid pathway leads to the formation of not only aromatic amino acids but also a plenty of secondary metabolites. The crucial enzyme shikimate dehydrogenase is there a part of bi-functional protein 3-dehydroquinate dehydratase/shikimate dehydrogenase (DHD/SDH; EC 4.2.1.10 and EC 1.1.1.25). Whereas the regulation of the shikimic pathway is complex, little is known about the feedback regulation of plant SDH.