ИСТИНА

Small signaling peptides (SSP, typically 5-75 aa in size) are a fast growing class of regulatory molecules involved in practically all aspects of plant vital activity including morphogenesis, in particular regulation of cell division and differentiation in meristems, cell expansion, main root and lateral root development, immune and other responses to environmental stimuli. For Arabidopsis thaliana, more than 1000 SSP sequences are already postulated; however, only few of them have been functionally characterized and linked to a putative receptor. One of the best-studied pair of a SSP and its putative receptor is a peptide CLV3 (RTVPSGPDPLHH, designed here as RTV) and a receptor like kinase, CLV1. Genes coding them are expressed in shoot apical meristem of Arabidopsis, and this ligand/receptor pair modulates stem cell maintenance or cellular differentiation in shoot meristems. However, it has been shown that application of RTV in the culture medium of Arabidopsis influences root growth though no putative receptors of it have been identified in roots. We studied the effects of the synthetic peptide RTV in a wide range of concentrations including ultra-low ones on the dynamics of the main root and lateral roots growth of Arabidopsis and also its effects on spontaneous processes with reactive oxygen species (ROS) participation that constantly go on in aqueous bicarbonate solutions. RTV inhibits growth of the main root in concentrations from 10-6 to 10-9 M and from 10-14 to 10-16 M, while in concentrations of 10-11 -10-12 M it statistically significantly stimulates main root growth. Hence in the range of low and ultra-low concentrations a bi-phasic (hormetic) effect of RTV on the main root growth (indication of cellular proliferation) was observed. RTV affected also appearance of lateral roots (indication of differentiation). It is notable that most intense stimulation of the appearance of lateral roots was produced by concentrations of RTV exerting inhibitory effects on the main root growth. The balance between cellular proliferation and differentiation is a key aspect of development in multicellular organisms. This balance in Arabidopsis roots is modulated by the balance of reactive oxygen species (ROS) between the zones of cell proliferation and the zone of cell elongation where differentiation begins [ ]. In this connection it was notable that addition of RTV to aqueous solutions of bicarbonates, where ROS are constantly produced changes the parameters of free radical reactions evaluated by measuring the intensity of stimulated photon emission from these solutions. Effects of RTV changed in a wide range of its concentrations also non-monotonously being most strong in those concentrations that most effectively inhibit main root growth and stimulated lateral roots growth (10-7 - 10-8 M and 10-14 - 10-16 M) . We previously suggested [ ] that a stable non-equilibrium state (electronically excited) in bicarbonate systems is provided by spontaneous charge separation in aqueous systems (G. H. Pollack). Such a state may be highly sensitive to low intensity physical and chemical factors acting upon the structural-dynamical processes in aqueous systems via resonance mechanism. It is notable that all peptides and polypeptides are characterized by peculiar distribution of hydrophilic and hydrophobic aa side groups along the peptide chain providing specific hydration atmosphere for each particular peptide. On the other hand the common future of all peptides is the presence of multiple peptide bonds. According to Gilbert Ling’s “Polarized Multilayer Theory” [ ] dipolar backbone NH and CO groups are the primary seats of water sorption. In oligopeptides to which RTV belongs it is highly probable that sufficient quantity of peptide bonds are open for interaction with water and hence are capable to form multiple layers of highly polarized water molecules that may dynamically modulate structural-dynamical processes in aqueous systems. It is interesting to speculate that these two features of SSP – specific hydration atmosphere and ability to form multiple layers of highly polarized water may provide for their versatile role in regulation of multiple biological functions not only in plants but in all living systems.