Effect of 12-hydroxy-9(Z)-dodecenoic acid on growth and cell division in pea roots

It is known that potential bioregulators may be present among lipoxygenase oxidation products. A possibility of mitotic cycle regulation by 12-hydroxy-9(Z)-dodecenic acid (12-HDA) and also its influence on the growing function (seed germination, root and epicotyl growth) have been studied. It has been determined that 12-HDA activity is directed to the strengthening of growing function which allowed to suppose that oxylipin is capable of regulating cell division. 12-HDA participation in the mitotic cycle regulation were determined by the originally developed test system using simultaneously light microscopy. The concentration and temporal dependencies of cell division were studied under the influence of 12-HDA. The raise of mitosis (up to 17.5 times) has been registered in comparison with the control variant by the least concentration of 12-HDA (10(-9) M) up to the 4th h of influence, confirming oxypilin participation in mitotic cycle regulation.     

Modern aspects of studying phytohormones. Cytokinins

The review presents current data on mechanisms of cytokinin action in plants. By analogy with the first part (Ivanova et al., 1999), in which general principles of phytohormone action and cardinal trends of phytohormone investigations were examined, here the relevant information on mechanisms of action of auxins and gibberellins has been given, and taking cytokines as example an attempt has been done to summarize the literature data on the number of questions offered for analysing hormones of high animals (Gudwin, Merser, 1986). The review demonstrates that mechanisms of cytokine action at the cellular level are not known in many cases. One of the most significant factors in the action of phytohormones of this class on plants is their concentration, determined by their synthesis, transportation and further chemical conversions. This paper points to a poor knowledge of the relative role of these processes in regulation of cytokinin contents and their distribution among plant organs. Two possible ways of studying cytokinin action at the present day stage of investigations have been designated: 1) revealing the cytokinin expressed genes and establishing mechanisms of their action; 2) estimation of endogenous cytokinin alteration and the influence of this alteration on definite processes in the cell with the help of ipt-gene from t-DNA of Agrobacterium tumefaciens.     

The influence of methyl jasmonate on the growth processes in the pea

The influence of methyl jasmonate (MJ) on pea growth was studied. Stimulation of seed germination by MJ [10(-9), 10(-6) M] was carried out for 24 h. MJ [10(-9) M] intensifies the epicotyl growth, and MJ [10(-6) M] inhibits the epicotyl and root growth. Season dependence of mitosis regulation was determined. The maximum intensity was observed early in spring with MJ [10(-6) M], and autumn with MJ [10(-9) M], with almost one order less intensity, the latter intensity being one order less, suggesting a general loss of cell sensitivity to regulator. The peak of mitotic activity in summer was between the spring and autumn peaks due to the low concentration of effector. It is supposed that jasmonoids are able to coordinate cell entry to mitosis in different seasons.