We studied the dependence of cytokinins accumulation in the shoot apexes of Arabidopsis plants on the delivery of these hormones from the roots. For the estimation of cytokinins content in the cells the method of immunohystochemical localization was used using antibodies against zeatin riboside. To prevent washing of cytokinins during the process of dehydration we used the method of differential conjugation of free cytokinins bases and their ribosides. Root cutting has been shown to weaken the immunostaining of zeatin in the cells of the shoot apical meristem thereby supporting the hypothesis about dependence of cytokinins accumulation in these cells on the hormone delivery from the roots. We detected a decline in the level of cytokinins in the cells of the shoot apex as affected by protonophor indicating important role of the process of secondary active transport through the cell membrane for the maintenance of cytokinins level in the cells of the shoot apex.

Представлены данные о влиянии повышения температуры воздуха на 4°С на рост листьев и параметры водного обмена у растений ячменя (Hordeum vulgare L.) сорта Steptoe и его дефицитного по АБК мутанта (AZ34). Увеличение температуры вначале привело к прекращению удлинения листьев у растений обоих генотипов, однако затем у растений Steptoe полностью восстановилась скорость прироста листа в отличие от мутантных растений. До изменения температуры воздуха уровень транспирации был выше у мутантных растений, а с ее повышением транспирация увеличивалась у растений обоих генотипов. После восстановления роста водный потенциал листьев Steptoe несколько увеличился по сравнению с первоначальным уровнем (до повышения температуры). У листьев AZ34, наоборот, водный потенциал, который изначально был ниже, чем у листьев Steptoe, после повышения температуры уменьшился. Расчет общей гидравлической проводимости в побегах и осмотической гидравлической проводимости корней показал, что эти показатели возросли у Steptoe и остались без изменений у AZ34. При повышении температуры у растений AZ34 уровень АБК не менялся, а у растений Steptoe возрастал в корнях и снижался в побегах. Сделан вывод, что способность к синтезу АБК необходима для контроля общей гидравлической проводимости при изменениях условий окружающей среды.

Here we have shown that 24 hours after addition of zeatin to the nutrient solution the cytokinin content in xylem sap of wheat plants appears to be about 10 times lower that in the nutrient solution. Cytokinins accumulated mostly in roots and not in shoots of treated plants. These data demonstrate the existence of some barrier on cytokinin pathway from the nutrient solution to the plant shoot. With the help of Sudan III an increase in lignin and suberin deposition in the endodermis could be detected, being stronger with the increase in the distance from the root tip. The increase in deposition of suberin and lignin coincided with the decrease in cytokinin immunolabeling in root cells revealed with the help of monoclonal cytokinin antibodies and the second gold-labelled antibodies. Simultaneously exogenous cytokinins accumulated in root stele cells showing that the Casparian band was not only barrier on cytokinin pathway to plant shoot. It is concluded that high cytokinin immunolabe ling in the stele parenchyma cells around the stele vessels demonstrated accumulation of cytokinins by these cells, which could be important in regulation of cytokinin loading to the xylem vessels during there transport to the shoot. The role of cytokinin transporters is discussed.

The regulative role of ABA in the rapid plant stomatal reactions in response to salinity was investigated. The influence of the short-term salinity on the overall ABA accumulation and its distribution within the mature leaf (revealed by immunohystochemical technique) and stomatal conductance of barley (Hordeum vulgare L.) were determined. Rapid bulk leaf ABA accumulation and increase in ABA immunolabeling in the mesophyl and guard cells of stomata were shown. The bulk ABA increasing in mature barley leaves coincided with stomatal closure induced by salt treatment indicating on the ABA contribution to the rapid stomatal closure.