Content Of Gibberellin-like Substances Research Articles

THE INFLUENCE OF PLANT GROWTH REGULATOR BIOLAN ON THE PHYTOHORMONAL ACTIVITY OF ENTEROBACTER NIMIPRESSURALIS 32-3

The influence of plant growth regulator Biolan on the ability of bacterium Enterobacter nimipressuralis 32-3 to synthesize phytohormones was investigated. It was revealed, that addition of Biolan in a nutrient medium had increased the quantity of indole-acetic acid (IAA) and citokinins (by 13,6 and 18 % correspondingly), and had reduced on 15 % the content of gibberellin-like substances.

Changes in Phytohormone Status in Stems and Roots after Decapitation of Pea Seedlings

Experiments were performed on the first and second internodes and 4-cm-long apical segments of main roots of pea (Pisum sativum L.) seedlings, grown in the light and decapitated above the second node on the seventh day after seed germination. Endogenous phytohormones were measured by the enzyme-linked immunosorbent assay during three days after decapitation of seedlings. The IAA level in the internodes decreased 2–3 times on the second day after decapitation of seedlings while the cytokinin level increased 5–6 times for zeatin and zeatin riboside (Z and ZR) and 1.5–2 times for isopentenyl adenine and isopentenyl adenosine (IP and IPA). In contrast to internodes, the IP and IPA contents in the roots of decapitated seedlings did not change, but the levels of Z and ZR increased 1.5–2 times compared to intact plant roots. The IAA level in the apical region of root remained almost unchanged after the removal of shoot apex. It was concluded that the apical meristem of the main root is not the site of the cytokinin response to the auxin signal coming from the stem apex and that a slight accumulation of Z and ZR after decapitation is due to upper zones of the root. There was no difference in the content of gibberellin-like substances between the internodes of intact and decapitated seedlings. However, the content of gibberellins (GA) in the root tip decreased after decapitation of seedling, which suggests an essential role of apical bud in supplying the root with GA and/or intermediates for their biosynthesis.

Gibberellins and the Legume-Rhizobium Symbiosis

The content of gibberellin-like substances in nodules formed by Bradyrhizobium species strain 127E14 on roots of lima bean (Phaseolus lunatus L.) has been previously found to be relatively high. The objectives of the present study were to purify and identify the endogenous gibberellins from the stems and nodules of lima bean. By sequential silica gel partition column chromatography, C(18) reverse-phase high performance liquid chromatography, and combined gas chromatography-mass spectrometry, the gibberellins A(1), A(3), A(19), A(20), A(29), and A(44) were identified from root nodules. Gibberellins A(1), A(3), A(19), A(20), and A(44) were also identified from lima bean stem tissue. These data provide the first mass spectral-based evidence that gibberellins are present in leguminous root nodules. The presence of the gibberellins identified indicates that the early 13-hydroxylation gibberellin biosynthetic pathway predominates in stem and nodule tissue. However, it is not known if the gibberellins within the nodules are produced in situ, or if they are imported from some remote host plant tissue.

Changes in endogenous gibberellins in plant organs producing and utilizing photosynthates

The distribution of endogenous gibberellin-like substances in individual organs ofZea mays L., cv. CE 250, plants was investigated during the transition from the vegetative to the generative phase of development. The gradient of the content of gibberellin-like substances and photosynthetic activity in leaf segments was followed in different parts of the Jeaves, as well as the changes in the content of gibberellin-like substances in leaf segments during an exposure in the light and in the dark. The gradient of the content of endogenous gibberellin-liko substances in the leaves, in the stem and in the spike is interpreted in terms of possible relationship of these compounds to the regulation of sink — source.

Changes in endogenous growth regulating compounds during the after-ripening of the dormant seeds of groundnut

Summary Changes in percentage germination and growth regulating compounds were studied (isolated by chromatography) in cotyledons and embryonic-axes separately during the dry storage after-ripening of the dormant groundnut seeds ( Arachis hypogea L.). The content of inhibitory phenolic acids (P-coumaric, ferulic, P-hydroxybenzoic and vanillic acids) decreased and the synergistic ones (chlorogenic, caffeic and protocatechuic acids) increased during the breaking of dormancy. Coumarin also declined during the dry storage. Growth inhibitor content went down while the low auxin content in the dormant seeds rapidly increased during the after-ripening. The content of gibberellin-like substances in the after-ripened seeds was higher than in the dormant seeds.

The role of endogenous gibberellin-like substances and inhibitors in the growth of pea internodes

Third internodes or whole stems of 7-days old etiolated pea plants were extracted and the content of gibberellin-like substances and inhibitors has been determined. Extracts were found to contain four or five different gibberellin-like substances, some of which are chromatographically similar to GA3. The content of gibberellins has been high in young internodes and decreased along with the internodes elongation. Brief red light irradiation brings about quantitative changes in gibberellin content, depending also on the length of internodes. The extracts contain acidic and neutral inhibitors which interfere with the response to GA3. The content of the inhibitors does not seem to be affected by the ageing of internodes or by the light treatment.

Gibberellin-like Substances in the Sporophores ofAgaricus bisporus(Lange) Imbach

Sporophores of cultivated Agaricus bisporus (Lange) Imbach, were shown to contain a gibberellin-like substance active in the dwarf maize (d-5), «-amylase and other bioassays. Ethyl-acetate extraction followed by paper, column, and thin-layer chromatography revealed the presence of one major active substance. Ficin hydrolysis of dried sporophore powder, after the complete removal of free substances, released more gibberellin-like substances, one of which appeared identical to the free compound. The free substance was predominantly in the lamellae and residual pileus tissue. The major active substance released by ficin occurred mostly in the lamellae but also in substantial equal amounts in both stipes and pilei. No activity was found in extracts of dikaryotic vegetative mycelium on malt agar. The level of activity in extracts from sporophores stored at — 20 °C fell sharply after 7 d, and then remained constant over a period of 6 weeks. The content of gibberellin-like substances in young and old whole sporophores showed wide variation between experiments. In most cases young 2-d tissue had higher levels than old, 11-d tissue on a fresh weight basis. Purified sporophore extracts and authentic gibberellins had no stimulating effect on growth of sporophores or of cultured vegetative mycelium. The inhibitors of diterpene biosynthesis, CCC, and AMO-1618 induced a small increase in mycelial growth rate. Ethyl acetate extraction of horse-straw compost prior to inoculation with Agaricus bisporus showed the presence of gibberellin-like activity in significant amounts.

Role of growth regulators in differentiation processes of maize (Zea mays L.) organs

The following paper deals with the character of endogenous auxins and gibberellinlike substances in the maize tassel and ear primordia during differentiation. Using bioassay the character of substances extracted from tassel primordia, internodes below the tassel, ear primordia and stem base was determined and correlated with the course of morphogenesis and differentiation. A low level of auxins and a high content of gibberellin-like substances accompanies the differentiation of terminal tassel. The differentiation of an ear is associated with an increment in auxin content while the level of gibberellin-like substances decreases. The character of growth substances in primordia remains practically unchanged in the course of further differentiation. The inhibitions appear in the plant and probably start numerous morphological reductions in the pistillate inflorescence structure or inhibit the growth of lateral primordia on the stemetc. The treatment of plants with maleic hydrazide at the beginning of tassel differentiation shifts the normal levels of endogenous regulators and brings about the transformation of tassel primordia into an ear. This transformation is accompanied by a marked rise in gibberellin-like substances, by an increment in auxins and the appearance of inhibitors.

A preliminary study of changes in the content of gibberellin-like substances in the potato plant in relation to the tuberization mechanism

Changes in the content of gibberellin-like substances were followed in shoots and roots during different periods of the vegetative cycle (pre-tuberization; tuber initiation; tubers 1–2 cm in diameter; tubers fully grown). The extractions were made with ethyl alcohol and the extracts were divided into acid and neutral fractions after previous treatment with ethyl acetate. Before tuberization the shoots contained large quantities of gibberellin-like substances which decreased after tuberization. On the other hand, the roots contained high concentrations of antigibberellin-like substances which disappeared after tuber initiation. It is suggested that these substances are of importance in the control of the mechanism of tuberization, on the basis of a hypothesis previously propounded.

On the flower head formation and development of cauliflower plants. I

In order to obtain the physiological data concerning the flower head initiation of cauliflower plants by low temperature, this experiment was carried out with Nozaki-wase grown in the experimental field and with Early Snowball A grown at various temperatures in the phytotron, analysing auxins and gibberellin-like substances in the apical part and chemical constituents in the stem of plants.1. Seedlings planted early in spring received the effect of low temperature immediately after transplanting, while seedlings planted in summer grew for a while under favorable condition for vegetative growth following the transplanting and then were exposed to low temperature. Thus the latter were larger than the former at the stage of flower head initiation.The following analytical results were noted with these materials.(1) Carbohydrates and nitrogen compounds gradually increased with the progress of age and especially soluble sugar was accumulated remarkably in the stem of both plants sown in spring and summer, resulting in the highest level at the stage of flower head initiation followed by a rapid decline.(2) A temporary decline of auxins, especially in the Rf value of IAA, was clearly shown immediately before flower head initiation in both plants sown in spring and summer.(3) The content of gibberellin-like substances was small amount at the vegetative stage and increased considerably after flower head induction.(4) DNA content was fairly constant at the vegetative stage in spite of the different size of seedlings sown in spring and summer, but thereafter gradually increased following flower head induction, while RNA increased rapidly with the progress of age, resulting in a peak immediately before flower head initiation, corresponding with the time of a temporary decline of auxin.From the analyses of nucleotide components of RNA in apical parts of plants at the vegetative stage and reproductive stage, it was found that the ratio of purine base to pyrimidine base was high at the vegetative stage in contrast to the low value at the reproductive stage.2. When Early Snowball A seedlings were exposed to 10, 17 and 25°C respectively, the flower headd ifferentiated after five days at 10°C and after ten days at 17°C, but did not differentiate in the Plants grown at 25°C.Corresponding with those responses to temperature treatment, the following analytical data were obtained.(1) In the stem of plants grown at 25°C, carbohydrates and nitrogen compounds accumulated gradually, whereas the former rapidly increased and the latter decreased with the decline of treated temperature. And the highest vahle of carbohydrales and nitrogen compounds were shown at the stage of flower head induction of plants grown at each temperature.(2) It was observed that the gibberellin content considerably increased following flower head induction, in other words, from the 10th day after the exposure treatment to 10°C and from 15 th day to 17°C respectively.(3) Litlle DNA was found in apical parts of Plants grown at various temperatures during the course of vegetative growth followed by a gradual increase at the reproductive stage.On the other hand, a rapid increase in RNA was found in apical parts of plants grown at 25°C with the progress of age, whereas 10°C and 17°C treatments did significantly decrease the RNA level, the decrease being earlier and greater with the decline of treated temperature.3. From the above-mentioned results it may be suggested that the flower head initiation of cauliflower plants is induced by the qualitative conversion of RNA, that is, relative increase in pyrimidine base and decrease in purine base of RNA component due to a temporary decline of auxins in apical pazts of plants by low temperature.