Cytokinin stimulated growth

Ethylene as a stimulator of growth and development. The most observed actions of ethylene on growing plants involves growth inhibition, or acceleration of senescence. These actions are especially evident in the antagonism or opposition of ethylene to auxins, gibberellins and cytokinins (27), as already outlined above. Actually ethylene stimulates growth in many types of cells, especially in water plants (Table II). When ethylene acts to stimulate cell elongation, as in water plants, auxins and CC>2 enhance the ethylene effect (38,39). This interaction is the reverse of that observed on land plants wherein ethylene opposes the effects of auxin, GA3 and cytokinins. 

Phenyl-l,2,3-triazolo[4,5-d]pyrimidin-7(6//)-one has bactericidal activity against Bacillus subtilis and Staphylococcus aureus (94MI2). 1-Benzyl-4-ethoxycarbonylpiperazinyl-l//-l,2,3-triazolo[4,5-d]pyrimidine almost completely removed cytokinin-stimulated effects in betacyanin synthesis in Amaranthus caudatus cotyledons, growth of radish cotyledons, and retention of chlorophyll in leaf explants (94MI4). Analogs of 117 were used as effective inhibitors of xanthine oxidase (95FA257). 

Compounds of non-adenine structure were sought based on the considerations of steric similarities between A -substituted adenine and phenylurea and also between phenylurea, A-arylcarbamates and s-triazine herbicides. Many of the compounds found are known as inhibitors of photosystem 11 electron flow and some also inhibit the cytokinin-stimulated callus growth [36,37]. It has been concluded that phenylureas, s-triazines and V-arylcarbamates share the same place of action, which is the cytokinin receptor localized in chloroplasts [28]. 

After 8 weeks from the inoculation, shoots appeared on all the media, demonstrating maximum 5 shoots per segment on B5 medium containing 0.01 mg/1 NAA plus 3 or 5 mg/1 BA, Fig. (3). Although the effect on addition of single cytokinin was also examined, cytokinin in combination with low concentration of auxin was even more effective, which may be attributable to the shoot growth stimulant effect of auxin in low concentration [18]. Shortened intemodal length of shoots was observed by the addition of BA, Fig. (3). 

Brassinosteroids are reported to stimulate overall plant growth and development, especially under stress conditions, to enhance auxin-induced growth as well as auxin-induced ethylene production (5, 6). Brassinosteroids interact with most of the phytohormones, such as cytokinins and gibberellins, and in particular with auxin. 

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