USE OF NEW COMPOUNDS OF THE QUINOLINE SERIES AS EFFECTIVE STIMULANTS OF GROWTH PROCESSES

The results of a study of the action of compounds of the general formula: 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2-dihydroquinoline and 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2,3,4-tetrahydroquinoline are presented. The most effective growth stimulants from compounds of the series 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2-dihydroquinoline and 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2,3,4-tetrahydroquinoline for yellow rhododendron (Rhododendron luteum) and Ledebur rhododendron (Rhododendron ledebourii) were revealed. Rhododendron seedlings were counted to study laboratory germination and planted in crates in closed ground on 21 days after the start of the experiment. It was established that the synthesized chemicals cause stimulation of the growth of species of the genus Rhododendron in comparison with existing commercial preparations. The efficiency of using solutions of compounds of the series 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2-dihydroquinoline and 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2,3,4-tetrahydroquinoline and their concentrations. A method of using compounds of this series as growth stimulants is disclosed, which allows increasing seed germination of species of the genus Rhododendron from 20 to 50%, increasing the height of Rhododendron luteum seedlings from 18 to 63%, and Rhododendron ledebourii from 33 to 183 %. Dihydroquinolines are most effective for species of the genus Rhododendron. Compounds containing a dihydro-6-quinolinyl substituent stimulate the growth of these plants. The specificity of the action of growth stimulants is noted. The expediency of using quinoline series compounds for the production of planting material of ornamental plants for landscaping is shown. It is suggested the auxin activity of compounds of the general formula: 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2-dihydroquinoline and 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2,3,4-tetrahydroquinoline. It is assumed that compounds of the series 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2-dihydroquinoline and 1-alkyl-2,2,4-trimethyl-6-aminocarbothioyl-1,2,3,4-tetrahydroquinoline may have the stressprotective activity for species of the genus Rhododendron. The materials of the article are of practical value forbiologists, ecologists, plant growers.

Auxin regulates endosperm cellularization in Arabidopsis

The endosperm is an ephemeral tissue that nourishes the developing embryo, similar to the placenta in mammals. In most angiosperms endosperm development starts as a syncytium, where nuclear divisions are not followed by cytokinesis. The timing of endosperm cellularization largely varies between species and the event triggering this transition remains unknown. Here we show that increased auxin biosynthesis in the endosperm prevents its cellularization, leading to seed arrest. Auxin-overproducing seeds phenocopy paternal-excess triploid seeds derived from hybridizations of diploid maternal plants with tetraploid fathers. Concurrently, auxin-related genes are strongly overexpressed in triploid seeds, correlating with increased auxin activity. Reducing auxin biosynthesis and signaling reestablishes endosperm cellularization in triploid seeds and restores their viability, highlighting a causal role of increased auxin in preventing endosperm cellularization. We propose that auxin determines the time of endosperm cellularization and thereby uncovered a central role of auxin in establishing hybridization barriers in plants.

THE DYNAMICS OF ENDEGENOUS HORMONES ACTIVITY IN PLANT LEAVES DEPENDING ON THE ALTITUDE OF THEIR GROWING

The hormonal response of cultivated and wild plants to high intensity of UV-radiation and other stress factors of the highlands was studied. The activity of auxins and growth inhibitors substances in wheat (Triticum aеstivum L), barley (Hordium vulgare L), horse bean (Vicia faba L), and eurotia (Ceratoides papposa) leaves, that grew in a field condition were analyzed at different stages of development, using thin-layer chromatography and bioassay. The leaves of cultivated plants (2320 and 2700 m above the sea level) and wild plants (2320 and 4000 m above the sea level) were collected at two elevations in Pamir highland (Tajikistan). The level of auxin activity at the beginning of ontogenesis in plant leaves that grew at both elevations was relatively higher in comparison with the activity of growth inhibitors. However, at the end of the vegetation period an increase in growth inhibitor activity was observed in plant leaves at both elevations. Increasing of the total auxin activity in plants was observed at low altitude compared to higher. Conversely, the activity of growth inhibitors substances increased in plants that grow at higher elevations.

Comparison of auxin activty in tumourous and normal callus cultures from sunflower and tobacco plants

In normal and tumourous calluses of sunflower and tobacco the level of extractable auxins was determined by <i>Avena coleoptile</i> straight growth test. Auxin activity was detected practically in two zones: I - at position with R_f 0.2-0.4 and II - at position with R_f 0.6-0.9. The tumour tissues of sunflower and tobacco plants, representing different types of neoplastic growth exhibit a 3 times higher auxin activity as compared with that of the corresponding normal tissues. Tobacco tissues, on the other hand, had a higher auxin level than the corresponding sunflower tissues and they exhibited different proportions in the activity of zones I and II, which points to a dominance of genetic regulation of hormone metabolism in these plants.

Changes in auxin activity in tumourous and normal tobacco calluses treated with morphactin IT 3233

The addition of morphactin IT 3233 in 1-40 mg/dm³ concentrations to the medium inhibited the growth <i>in vitro</i> of normal and tumourous tobacco calluses. The auxin activity (estimated by the <i>Avena</i> coleoptile straight growth test) of the acid ether extracts from these tissues increased. The activity of zone I (R_f 0.2-0.4, 0.5, solvent system: butanol:water:ammonia 10:10:1) in normal tissues increased more intensively than that of zone II (Rf 0.6-0.8, 0.9). In tumourous tissues, however, these changes were smaller and they concerned merely zone I of auxin activity (R_f 0.0-0.5). It seems that the mechanism of morphactin activity in both kinds of tissue is different. It may be supposed that the excessive accumulation of auxins induces growth inhibition of tissues. A previously found increase in the activity of IAA-oxidase influenced by morphactin might be considered as an adaptation to a higher level of IAA.