ИСТИНА

Physiological functions of peptides in the plant cells remain obscure. At the same time, the regulatory role and signaling of peptides are well studied in the animal kingdom. In the current study, experimental approaches are designed to isolation, separation and identification of endogenous peptides of the moss Physcomitrella patens. Measures were taken to avoid instrumental artifacts of protein degradation due to cell and tissue homogenization in peptide extract. Protoplasts, protonemata and gametophores of the moss are demonstrated for the first time to contain diverse small peptides derived from established protein precursors. Leafy shoots and filamentous protonemata of the moss are characterized by different composition of peptides and their protein precursors. Protoplast isolation from the moss protonemata is accompanied by degradation of proteins. Most of them mainly belong to the photosynthetic system. This process results in generation of endogenous peptides that is typical for stress reactions of higher plants. Thus, at the different stages of moss development, we identified endogenous peptides appearing as "physiological" proteolysis products. We assume that endogenous peptides in plant cells might not be just a source of amino acid building blocks for further protein synthesis. The potential signal, regulatory and physiological functions of the endogenous moss peptides are discussed.