Phytosulfokine-α (PSK), a peptidyl plant growth factor, has been recognized as a promising intercellular signaling molecule involved in cellular proliferation and dedifferentiation. It was shown that PSK stimulated and enhanced cell divisions in protoplast cultures of several species leading to callus and proembryogenic mass formation. Since PSK had been shown to cause an increase in efficiency of somatic embryogenesis, it was reasonable to check the distribution of selected chemical components of the cell walls during the protoplast regeneration process. So far, especially for the carrot, a model species for in vitro cultures, it has not been specified what pectic, arabinogalactan protein (AGP) and extensin epitopes are involved in the reconstruction of the wall in protoplast-derived cells. Even less is known about the correlation between wall regeneration and the presence of PSK during the protoplast culture. Three Daucus taxa, including the cultivated carrot, were analyzed during protoplast regeneration. Several antibodies directed against wall components (anti-pectin: LM19, LM20, anti-AGP: JIM4, JIM8, JIM13 and anti-extensin: JIM12) were used. The obtained results indicate a diverse response of the used Daucus taxa to PSK in terms of protoplast-derived cell development, and diversity in the chemical composition of the cell walls in the control and the PSK-treated cultures.
Keywords: AGPs; carrot; cell division; extensin; pectin; plating efficiency.