Chloroplast ultrastructure and amino acid composition of reserve protein in grain of barley and wheat treated with N,N-diphenylurea

The numerous data suggest an important role of phytohormones, particularly cytokinins, in regulation of plants growth and development. The cytokinins stimulates the cells division, takes part in cells differentiation and other physiological processes. In the present paper the effect of N,N-diphenylurea (DPU), a compound possessing cytokinine activity, on the rate of photophosphorylation and thylakoid membrane structure of chloroplasts in milky phase as well as on amino acid composition of reserve protein of barley ( Hordeum vulgare L.) of the Trumpf and Odesskii varieties and wheat ( Triticum aestivum L.) of the Moskovskaya 35 and Tulunskaya varieties was investigated. The treatment with DPU changed the rates of cyclic and acyclic photophosphorylation of thylakoid membrane isolated from flag leaves of treated plants and induced destructive changes in chloroplasts. The changes in percentage ratio of a number of amino acids in reserve grain protein, especially proline, were shown. The modifications in mesophyll cells of chloroplasts after DPU treatment suggest that an action of this compound at the beginning of milky phase accelerates the process of plants aging, but its action at the beginning of flowering phase results in converse effect. A conclusion was done that DPU controls energy metabolism in the leaves and protein exchange in grain of wheat and barley plants.