Influence of Glycylglycine, Glycine, and Glycylaspartic Acid on Growth, Development, and Gene Expression in a Tobacco (Nicotiana tabacum) Callus Culture

Abstract

The dipeptides glycylglycine (GlyGly) and glycylaspartic acid (GlyAsp) and amino acid glycine (Gly) in a concentration of 10^–7 M in a medium essentially stimulate the growth and development of tobacco (Nicotiana tabacum) calli. GlyGly, GlyAsp, and Gly influence the cell differentiation and tissue formation processes. They stimulate formation and growth of leaves and roots. After incubation of tobacco seedling roots in the presence of 10^–5 M fluorescent FITC-labeled peptides or glycine, marked fluorescence was observed in cells of the root cap and epidermis. The fluorescence was detected in the cell walls, cytoplasm, and nuclei. Thus, the peptides used can penetrate into the plant cell and be located in the nucleus and other cell compartments. Therefore, they may potentially interact with different structures and components of the cytoplasm and nucleus including various proteins, RNAs, and DNA. The penetration and accumulation of peptides in cells are tissue specific. In the tobacco callus, peptides modulate expression of the KNOX and GRF family genes that are responsible for cell differentiation and code for transcription factors. Thus, the dipeptides GlyGly and GlyAsp and amino acid Gly have marked physiological activity and can be related to efficient plant growth regulators.