RESUMEN
The effect of fusicoccin on the common wheat genome (cv. Mironovskaya 808) during early phases of seed germination was studied. It was shown that fusicoccin: (1) increased the number of cells with one or two nucleoli and decreased the proportion of cells containing three and four nucleoli; (2) enhanced the total volume of nucleoli per nucleus at a concentration of 0.68 mg/l; (3) did not activate additional rRNA genes on chromosomes 1B and 6B; (4) did not activate the latent nucleolus organizer regions on chromosomes of genome B; (5) induced associations of nucleolus organizer regions on B-genome chromosomes; (6) significantly enhanced mitotic activity in apical meristem of seedling root tips and promoted the first peak of mitoses; the effect disappeared after 44 h of seed imbibition; (7) in contrast to gibberellin, did not synchronize cell division; (8) did not cause chromosome and chromatid aberrations and increase the frequency of sister chromatid exchanges at physiologically active concentrations. Presumable mechanisms of fusicoccin-induced activation of rRNA genes are discussed in relation to the identification of the fusicoccin receptor belonging to the GF14 proteins with an intracellular binding site, to the detection of endogenous fusicoccin in plants in vivo, and to fusicoccin-induced activation of gene transcription.
Asunto(s)
Genoma de Planta , Triticum/efectos de los fármacos , Nucléolo Celular/efectos de los fármacos , Núcleo Celular/efectos de los fármacos , Cromosomas/efectos de los fármacos , Glicósidos/farmacología , Región Organizadora del Nucléolo/efectos de los fármacos , ARN Ribosómico/genética , Triticum/genética , Triticum/ultraestructuraRESUMEN
All higher plants possess highly specific binding sites for fusicoccin, a metabolite of the fungus Fusicoccum amygdali Del. These sites are harboured in the plasma membranes and formed by a 14-3-3 protein dimer associated with the C-terminal autoinhibitory domain of H+-ATPase. We considered the fusicoccin binding to plasma membranes to be an indicator of complexation between the 14-3-3 dimer and H+-ATPase, we assessed the effect of cold stress on the interaction of these proteins in suspension-cultured sugar beet cells and protoplasts derived from these cells. In both objects, upon lowering the temperature to 0-4 degrees C, a portion of the cytoplasmic 14-3-3 proteins became associated with the plasma membrane, which showed an increasing amount of ATPase/14-3-3 complexes and enhanced ATPase activity. Association between ATPase and 14-3-3 resulted in a several-fold rise in the H+ efflux from protoplasts and intact cells. We suppose that regulation of the H+ pumping under changing external conditions may be based on the interaction between H+-ATPase and the 14-3-3 proteins.
Asunto(s)
Membrana Celular/metabolismo , Chenopodiaceae/fisiología , Frío , Proteínas/metabolismo , ATPasas de Translocación de Protón/metabolismo , Tirosina 3-Monooxigenasa , Proteínas 14-3-3 , Sitios de Unión , Células Cultivadas , Chenopodiaceae/citología , Citoplasma/metabolismo , Glicósidos/metabolismo , Protoplastos/metabolismoRESUMEN
Radioimmuno- and radioreceptor assays were developed for quantitating fusicoccin-like substances in plants. FC-like ligands were found in cultured horseradish roots (70-90 pmol/g) and headed cabbage leaves (9-11 pmol/g). Detection of FC-like ligands in sterile root culture further argues in favour of endogenous fusicoccin representing a new type of phytohormone.
Asunto(s)
Glicósidos/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Proteínas de Plantas , Plantas/metabolismo , Receptores de Superficie Celular/metabolismo , Ligandos , Técnicas de Cultivo de Órganos , Radioinmunoensayo/métodos , Ensayo de Unión Radioligante/métodos , Zea mays/químicaRESUMEN
The influence of composted peat on the effectiveness of different doses of mineral fertilizers was studied in model greenhouse experiments with barley of the Pirkka variety cultivated in sand and poorly cultivated sandy-loam soil. It was shown that the use of a large amount of composted peat (10% of the weight of the substrate) contributed under the experimental conditions to a pronounced increase in plant productivity only when increased doses of mineral fertilizers were used (NPK at 0.2 g/kg of substrate). A direct correlation between yields and number of microflora in the rhizosphere was not revealed. Conditions were modeled under which increased yield occurred when development of microflora was poor, while the lowest yields were noted when there was an increase in the number of microorganisms. At the same time, the variants with maximal numbers of microorganisms and size of yields did coincide.