Contractile Proteins in Chemical Signal Transduction in Plant Microspores

Involvement of contractile components in chemical signal transduction from the cell surface to the organelles was studied using unicellular systems. Neurotransmitters dopamine and serotonin as well as active oxygen species hydrogen peroxide and tert-butyl peroxide were used as chemical signals. Experiments were carried out on vegetative microspores of field horsetail Equisetum arvense and generative microspores (pollen) of knight’s star Hippeastrum hybridum treated with cytochalasin B (an inhibitor of actin polymerization in microfilaments), colchicine, and vinblastine (inhibitors of tubulin polymerization in microtubules). Both types of the treated microspores demonstrated suppressed development, particularly, after cytochalasin B treatment. At the same time, increased blue fluorescence was observed in certain cell regions (along the cell wall and around nuclei and chloroplasts) where the corresponding contractile proteins could be localized. In contrast to anticontractile agents, dopamine, serotonin B, and peroxides stimulated microspore germination. Microspore pretreatment with cytochalasin B and colchicine followed by the treatment with serotonin, dopamine, or peroxides decreased the germination rate. The involvement of actin and tubulin in chemical signal transduction from the cell surface to the nucleus is proposed.