Possibility of formation of excited formaldehyde and singlet oxygen in biotic and abiotic stress situations.

The results obtained prove that singlet oxygen and excited formaldehyde can be liberated from hydrogen peroxide and formaldehyde in free and bound L-lysine containing plant and other tissues, similarly to the model reactions. It can be concluded that these reactive molecules have extremely high reactivity and are possibly aggressive to cellular components like proteins, nucleic acids and to microbial systems within plant and other tissues. However, the manifestation of their activity depends on level of quenching systems in plant and other tissues. It seems that these special reactions and their products may be an important part of the resistance potential (e.g. natural disease resistance) in biological systems.