Effect of plant growth regulators on in vitro fiber development from unfertilized and fertilized Egyptian cotton ovules

Unfertilized and fertilized ovules of Gossypium barbadense Giza 45 (extra long staple variety) were used to study the effect of plant growth substances (auxins, gibberellins and cytokinins) on in vitro fiber initiation and development. Kinetin, alone did not increase total fiber unit (TFU) of unfertilized ovules, while an increase in TFU value occurred when a constant level of IAA and GA₃ were used either separately or in combination in the liquid medium. GA₃ used alone, produced a higher TFU value than that produced by IAA, whilst, IAA with a constant level of GA₃ (5 M) produced the highest value of TFU. GA₃ with a constant level of IAA (5 M) produced a lower TFU value. Kinetin reduced the stimulatory effect of IAA and GA₃ on TFU value when used in combination with either substance. In fertilized ovules, the highest level of TFU was reached when IAA, with a constant level of GA₃, was added to the medium, whilst its lowest level was obtained when IAA was used alone. Estimation of in vitro fiber production, as well as the effect of growth substances used in different concentrations on in vitro fiber initiation and development from unfertilized and fertilized ovules of Egyptian cotton varieties Gossypium barbadense Giza 45 are discussed.     

Effects of root applications of gibberellic acid on photosynthesis and growth in C3 and C4 plants

The effects of root applications of gibberellic acid (GA₃) on growth and photosynthesis of 12 species of plants including C₃ monocots (Triticum aestivum L., wheat, Hordeum vulgare L., barley and Avena sativa L., oat), C₃ dicots (Vigna radiata L., mung bean, Cucurbita moschata L., squash and Capsicum annuum L., pepper), C₄ monocots (Zea mays L., corn, Sorghum vulgare L., sorghum and Panicum ramosum L., millet) and C₄ dicots (Amaranthus retroflexus L., pigweed, Kochia scoparis L., kochia and Gomphrena celosoides L., gomphrena) were evaluated. Relative growth rates (RGR) of barley, oat, squash, pepper, corn, sorghum, millet, pigweed and kochia were increased above the control by 12.7%, 9.9%, 11.3%, 10.7%, 19.2% 10.1%, 11.5%, 16.4% and 32.7% respectively, four days following optimum GA₃ treatments. There was no effect of GA₃ on RGR in wheat, mung bean, and gomphrena. Gibberellic acid decreased the chlorophyll content expressed on an area basis by 20.0%, 13.9%, 20.9%, 17.1%, 11.9% and 28.0% in barley, squash, pepper, sorghum, pigweed and kochia, respectively, while that of oat, wheat, mung bean, corn, millet and gomphrena remained unchanged. When photosynthetic rates were expressed per mg of chlorophyll, it showed that GA₃ could stimulate photosynthesis in barley, squash, pepper, sorghum, millet, pigweed and kochia by 20.4%, 20.6%, 16.5%, 17.4%, 10.4%, 24.2%, and 29.4%; while there was no effect in oat, wheat, mung bean, corn and gomphrena. An increase in leaf blade area and/or length of sheath were observed in GA₃ treated plants of oat, barley, mung bean, squash, pepper, corn, sorghum, millet and kochia. The transpiration rate remained unchanged following GA₃ treatment in all 12 species.This work was supported in part by the Fair Funds administered by the Pennsylvania Department of Agriculture. Contribution No. 39, Department of Horticulture, The Pennsylvania State University. Authorized for publications as paper no. 6886 in the journal series of the Pennsylvania Agricultual Experiment Station.Research assistant and assistant professor respectively.     

Effects of phytohormones on some biochemical parameters during dark induced leaf senescence ofSechium edule on Darjeeling Hill of the Eastern Himalayas

All the concentrations (25-150 mgl-¹) of the phytohormones kinetin, IAA (indol-3-ylacetic acid) and GA₃ (gibberellic acid) increased the activity of DCPIP (2,6 dichlorophenolindophenol)-Hill reaction, chlorophyll and protein contents over the control data in leaves ofSechium edule Sw. on Darjeeling hill of the Eastern Himalayas; while ethrel (2-chloroethylphosphonic acid) treatments decreased these parameters in the hilly species. The most effective concentrations in increasing these parameters were 50 mg 1-¹ of kinetin, 50 mg 1-¹ of IAA and 100 mg 1-¹ of GA₃; whereas 50 mg 1-¹ of ethrel was most effective in decreasing these parameters during the induction of senescence in the hilly vegetable crop. The increase in these parameters was greatest with kinetin, followed by IAA and least with GA₃ in the hilly plant species studied.     

Effects of some natural and synthetic growth regulators on sex-expression of Myrica esculenta Buch-Ham. ex D. Don

Gibberellic acid (GA,), chlorflurenol and ethrel were applied at different concentrations to either male or female trees of Myrica esculenta. GA₃ induced intersexual flowers both on the male and female trees whereas chlorflurenol and ethrel induced similar (intersexual) flowers but only on the male plants. When GA₃ was applied in combination with chlorflurenol, fewer intersexual inflorescences appeared on the male plants along with a significant decline in the number of flowers per inflorescence. In combination, chlorflurenol and ethrel induced copious female and intersexual inflorescences per male plant, especially when two successive treatments of 100 mg/I of chlorflurenol and 1920 mg/l of ethrel were applied. The induced female inflorescences later bore fruits.     

Hormonal regulation of tiller dynamics in differentially-tillering rice cultivars

Tiller number can contribute significantly to yield potential of rice, but little knowledge is available on hormonal regulation of tillering and tiller dynamics. In the present study, Indole-3-acetic acid (IAA), kinetin (6-furfuryl amino purine) and Gibberellic acid (GA₃) treatments have been applied at the early tillering stage to two rice cultivars that contrast for tiller number. The responses of the hormones were studied on growth, development, grain yield, senescence patterns, assimilate concentration of the panicle and ethylene production in different classes of tillers. The leaf area, panicle grain number, fertility percentage and grain yield of tillers were higher in the low-tillering cultivar than that of high-tillering cultivar; the treatment of kinetin was more effective in the latter than in the former. High ethylene production was responsible for reduction of growth duration and grain yield of the tillers. Kinetin application reduced ethylene production of the late-tillers significantly for the benefit of grain yield.     

Changes in photosynthetic rates and growth following root treatments of tomato plants with phytohormones

The effects of root applications of kinetin, gibberellic acid (GA₃) and indoleacetic acid (IAA) on photosynthesis was measured using an open infrared CO₂ gas-exchange system. There was a 30–35% increase in the photosynthetic rates (mg CO₂/dm²/hr) of attached leaves within 8 hr following root treatment with 0.47 M kinetin. On a short-term basis (up to 2 days) 0.47 M kinetin was shown to have the optimal stimulatory effect on photosynthesis, relative growth rate (RGR) and total plant dry weight. If the roots were in contact with 0.47 M kinetin for longer than two days there was severe branching of the root system and growth was severely decreased. When plants were left in contact with the kinetin treatment for up to 7 days the optimal stimulatory concentration was considerably lower (0.0047 M) . Plants receiving a 4, 8, or 12 hr pulse with 0.47 M kinetin to the roots exhibited higher leaf photosynthetic rates than the control. Plants receiving an 8 or 12 hr pulse with 0.47 M kinetin maintained photosynthetic rates higher than the control for the duration of the experiment (8 days) while the 4 hr pulse remained higher than the control for only 5 days. A sharp decrease in the photosynthetic rate, RGR and total plant dry weight was observed two days following continual treatments with 0.47 M kinetin to the roots. At low light levels there was approximately a 100% increase in the photosynthetic rate two days following treatment with 0.47 M kinetin while at a saturating irradiance there was a 30 to 35% increase. Indoleacetic acid either showed no effect on the photosynthetic rate, RGR and total plant dry weight or an inhibitory effect was observed. Either GA₃ or kinetin alone were shown to stimulate photosynthesis, RGR and total plant dry weight, however, when GA₃ at a 1.4 M concentration was applied in combination with kinetin at a 0.0047 M concentration to the roots of tomato plants there was no additive effect. In all cases kinetin dramatically reduced leaf resistance whereas GA₃ had no effect.By supplying either GA₃ or kinetin to the roots of tomato plants a highly reproducible stimulation in the photosynthetic rate, RGR and total plant dry weight can be achieved at physiologically relevant concentrations, whereas IAA appears to have an inhibitory effect.Approved for publication on July 29, 1981 as paper number 6281 in the journal series of the Pennsylvania Agricultural Experiment Station.Research Assistant and Assistant Professor, respectively.     

Comparison of gas chromatography-mass spectrometry,radioimmunoassay and bioassay for the quantification of gibberellin A9 in norway spruce (Picea abies (L.) Karst.)

Quantitative estimates of gibberellin A₉ in Norway spruce extracts obtained by gas chromatography-mass spectrometry, radioimmunoassay (RIA_ and bioassay were compared after successive purifications of the extracts. The extracts were assayed in several dilutions with and without the addition of standard gibberellin A₉, thus showing the effect of extract components on the response of the assays. Radioimmunoassay produced estimates comparable to gas chromatography-mass spectrometry after one purification step by high-performance liquid chromatography. Extracts purified by polyvinylpyrrolidone-column chromatography and solvent partitioning but not high-performance liquid chromatography resulted in inaccurate RIA estimates. The performance of the RIA could be monitored by logit-log transformations of the standard curve and extract dilution curve and by calculating the slope of the standard addition curve. It was, however, not possible to correct for the interference caused by extract components by the standard addition procedure. Quantifications by Tan-ginbozu dwarf-rice bioassay were accurate, but a large and unpredictable variation makes it unsuitable for quantitative determinations.Abbreviations FW fresh weight - GA₉ gibberellin A₉ - GA₉–Me methylated GA₉ - GC-MS gas chromatography-mass spectrometry - HPLC high performance liquid chromatography - MID multiple-ion detection - RIA radioimmunoassay     

The identification and metabolism of GA9 and its metabolites in seed coats and shoots of pea,line G2

[³H]gibberellin A₉ was applied to shoots or seed parts of G2 pea to produce radiolabeled metabolites. These were used as markers during purification for the recovery of endogenous GA₉ and its naturally occurring metabolites. GA₉ and its metabolites were purified by HPLC, derivatized and examined by GC-MS. Endogenous GA₉, GA₂₀, GA₂₉ and GA₅₁ were identified in pea shoots and seed coats. GA₅₁-catabolite and GA₂₉-catabolite were also detected in seed coats. GA₇₀ was detected in seed coats following the application of 1 g of GA₉. Applied [³H]GA₉ was metabolized through both the 13-hydroxylation and 2-hydroxylation pathways. Labeled metabolites were tentatively identified on the basis of co-chromatography on HPLC with endogenous compounds identified by GC-MS. In shoots [³H]GA₅₁ and [³H]GA₅₁-catabolite were the predominant metabolites after 6 hrs, but by 24 hrs there was little of these metabolites remaining, while [³H]GA₂₉-catabolite and an unidentified metabolite predominated. In seed coats [³H]GA₅₁ was the initial product, later followed by [³H]GA₅₁-catabolite and an unidentified metabolite (different from that in shoots), with lesser amounts of [³H]GA₂₀, [³H]GA₂₉ and [³H]GA₂₉-catabolite. [³H]GA₇₀ was a very minor product in both cases. [³H]GA₉ was not metabolized by pea cotyledons.Edited by T.J. Gianfagna.Author for correspondence     

Ethylene and CO2 affect direct shoot regeneration from the petiolar ends of Paulownia kawakamii leaves cultured in vitro

The effects of ethylene and CO₂ on shoot regeneration in excised leaf cultures of Paulownia kawakamii were examined. When both the gases were prevented from accumulating in the headspace of cultures using mercuric perchlorate and potassium hydroxide traps, shoot regeneration frequency improved and callus production was reduced compared to the control and cultures with only one of the gases trapped. Incorporation of either aminoethoxyvinylglycine (AVG) or 1-amino-cyclopropane-1-carboxylic acid (ACC) in the culture medium caused significant reduction in shoot regeneration. There was profuse callus production in the presence of high amounts of ACC, which was accompanied by over sixfold increase in the rate of ethylene production. However, in the presence of AVG callus production was delayed and shoot regeneration decreased, suggesting that low levels of ethylene might be needed for de novo shoot bud induction in Paulownia cultures.Abbreviations IAA Indole-3-acetic acid - MP mercuric perchlorate - AVG aminoethoxyvinylglycine - ACC 1-aminocyclopropane-1-carboxylic acid     

GA3和IAA对慈竹木质素生物合成相关酶活性调控及与木质素含量和S/G的关系

以慈竹为材料,通过叶面喷洒赤霉素（GA₃）和吲哚乙酸（IAA）,研究GA₃和IAA对慈竹木质素生物合成相关酶活性调控效应,以及相关酶活性与木质素含量和S/G比值的关系,为慈竹优质栽培和遗传改良提供理论依据。结果表明,GA-350IAA200处理对4CL酶活性具有促进作用;而GA-3200IAA50在处理后50天时对4CL酶活性起到明显的抑制作用,而且改变了4CL酶活性的动态变化趋势。GA₃和IAA对慈竹CAD酶活性具有促进作用;对PAL酶活性具有明显的抑制作用。相关分析结果表明,经过GA₃和IAA处理后,4CL酶活性与木质素含量和S/G比值呈不显著的负相关关系;PAL酶活性与木质素含量呈不显著的正相关关系;CAD酶活性与木质素含量和S/G比值呈不显著的正相关或负相关关系。结论,GA₃和IAA对慈竹木质素生物合成相关酶活性具有调控效应,而且这种调控作用与GA₃和IAA的浓度和配比有关。     

盐胁迫下赤霉素对黄瓜种子萌发及幼苗生长的影响

研究外源GA₃对盐胁迫下黄瓜种子萌发和幼苗生长的影响。结果表明,添加不同质量浓度GA₃的各处理,其发芽率、发芽势和发芽指数均显著高于NaCl胁迫处理,其中以100 mg/L GA₃处理的发芽势、发芽率和发芽指数最高,幼苗的叶面积、根长、根冠比也最大,同时叶片中叶绿素含量最高,幼苗叶片的光合速率(P_n)、气孔导度(G_s)、胞间CO₂摩尔分数(C_i)及蒸腾速率(T_r)等均达到最大;而当赤霉素的质量浓度为50 mg/L时,叶片中的POD活性为2 005 U/(g·min）,达最大值。     

Effect of light and gibberellic acid on cell division in the first foliage leaf of durum wheat (Triticum durum Desf.)

The present paper is part of a research program which aims at a quantitative analysis of the effects of light and gibberellic acid (GA₃) on growth of the first foliage leaf in durum wheat (Triticum durum Desf.). Since leaf growth is the combined result of the increase in cell number (cell division) and cell enlargement, the influence of light and GA₃ treatment on cell division in the basal meristem of the first leaf in two cultivars, Cappelli and Creso, was investigated. Creso is a short-strawed cultivar carrying the Gai 1 gene which influences both plant height and insensitivity to applied GA₃. Cell division, as measured by mitotic index, was similar in darkness, continuous red light and dichromatic irradiation (far-red plus red), while lower mitotic rates were observed under continuous far-red light: this indicates that the response of cell division is modulated by a high-irradiance reaction of phytochrome in both cultivars. The two cultivars showed different responses to blue light. In Cappelli, blue light and dichromatic irradiation (blue plus red) gave lower mitotic indices than the dark control, indicating the action of a specific blue-light-absorbing photoreceptor, whereas in Creso the response kinetics to all light regimes which included blue light were more complex. On the basis also of the results obtained with GA₃ application in Cappelli, it appears that (i) the hormonal treatment is able to change the pattern of mitotic index only in the presence of the action of a blue-light receptor and (ii) the different responses of the two cultivars could be the result of different endogenous hormonal levels. The importance of the observations in relation to the data for first-leaf longitudinal growth reported in a previous paper (Baroncelli et al. 1984, Planta 160, 298–304) is discussed.Abbreviations BL blue light - D darkness - FR far-red light - GA gibberellin - GA₃ gibberellic acid - m.i. mitotic index - Norflurazon 4-chloro-5-(methylamino)-2-(,,,-trifluoro-m-totyl-3(2H)) pyridazinone - R red light - WL white light - phytochrome photoequilibrium     

Effects of GA3 on Plant Physiological Properties,Extraction, Subcellular Distribution and Chemical Forms of Pb in Lolium perenne

The effects of growth-promoting hormone gibberellic acid 3 (GA₃) on physiology, Pb phytoextraction, and metal detoxification mechanisms in Lolium perenne were studied. Results showed that addition of GA₃ alone at lower doses (1 or 10 μM) facilitated antioxidant defense of L. perenne under Pb stress, decreased the toxicity of Pb in plant shoot by increasing the proportion of Pb in cell wall, hence significantly enhanced photosynthesis and plant growth, as well as Pb uptake and accumulation in L. perenne (P < 0.05). However, these indicators showed the opposite changes when treated with GA₃ at a higher dose (100 μM). Of the total Pb in plant shoot, 36–51% was associated with cell wall, and 31–40% was soluble fraction, while 41.4–49.7% was NaCl extractable, 24.6–35.4% HAc extractable followed by other fractions. These findings suggest that Pb fixation by pectates and proteins in cell wall and sequestration in vacuole are responsible for Pb detoxification in plant, and the GA₃ at 1 μM appears to be optimal for enhancing Pb phytoextraction by L. perenne from Pb polluted soils.     

Exogenous GA<Subscript>3</Subscript> overcomes bud deterioration in tulip (<Emphasis Type="Italic">Tulipa gesneriana</Emphasis> L.) bulbs during dry storage by promoting endogenous IAA activity in the internodes

Endogenous free IAA was examined with an immunohistochemical method for its involvement in the reduction of bud deterioration after GA₃ was injected into the bulbs. We found that tulip bulbs stored at 20°C constantly developed severe bud deterioration, whereas the symptoms of deterioration was lighter in the bulbs with GA₃ injection and not observed in the bulbs with 4°C treatment. 73% success in overcoming bud deterioration was achieved in 20°C with GA₃ treatment after 8 weeks of bulb storage, and the success rate was 7% after 12 weeks of storage. IAA was detected in the parenchyma cells in the internodes of the shoot after the bulbs were stored at 4°C or at 20°C with GA₃ injection for 4 weeks, but little was detected in the bulbs stored at 20°C constantly. Moreover, a weak IAA signal was present in between the cells of the internodes irrespective of bulb treatment. After planting, the bulbs that had been treated differently exhibited different flowering ability. The bulbs stored at 4°C for 4, 8 and 12 weeks attained high flowering percentage, which was lower in the 20°C with GA₃ treatment and lowest in the 20°C treatment. It may be concluded that GA₃ injection decreases bud deterioration of tulip bulbs during dry storage at 20°C by promoting the endogenous IAA in the internodes.     

GA3和Spd对杜鹃开花期光合特性和抗氧化系统的影响

为探讨GA_3和Spd对杜鹃(Rhododendron simsii)开花花期和开花品质的影响,研究了外源GA_3和Spd对杜鹃开花期光合特性和抗氧化系统的变化。结果表明,外源GA_3对花期有显著的提前作用,Spd对花期有明显的延迟作用,但两者均使花期延长、花径增大且成花率提高。GA_3和Spd处理提高了花期叶片的光合色素含量和净光合速率(Pn)、气孔导度(Gs)和胞间CO_2浓度(Ci);GA_3处理提高了叶片的蒸腾速率(Tr),而Spd使叶片的Tr下降,两者均有效缓解了末花期叶绿素含量的下降。GA_3和Spd处理显著降低了花瓣MDA含量,提高了抗氧化酶SOD、POD和CAT活性,并减缓了末花期SOD的下降,有效延缓了衰老进程,延长花期。以1 600 mg L~(–1) GA_3和0.10 mmol L~(-1) Spd处理效果较好,能有效提高杜鹃花的观赏品质。     

Relationship between gibberellic acid and water amount in the cotton seed

The role of endogenous GA₃ and its application to seed development in two cotton genotypes Hybrid-6 (H-6) (big seeds) and Gujarat cotton 13 (G. Cot) (small seeds) was studied. Kernel and seed coat were subjected to growth analysis in terms of dry weight, water amount, and rates of dry matter accumulation and water uptake. H-6 kernel had manifold higher dry weight and water amount than G. Cot. Seed coat of both genotypes had similar dry weight at maturity, but the maximum rates of dry matter accumulation and water uptake were distinctly higher in H-6. According to growth analysis, development of seed kernel and coat was subdivided into four phases, i.e., cell division, cell elongation, dry matter accumulation and maturation. Endogenous GA₃ level was estimated in kernel and seed coat by indirect ELISA using antibodies raised against GA₃. GA₃ amount per seed components was higher in the seed kernel of H-6 than of G. Cot, except 33 and 36 days after anthesis in kernel. H-6 seed coat had the higher amount of GA₃ during cell division phase than that of G. Cot. Close correlation between in vivo GA₃ level and water amount was recorded in both seed components. With GA₃ or GA₃ + NAA treatments in ovule culture, higher promotion in dry weight, water amount and seed size was noted in G. Cot than in H-6 suggesting that G. Cot is more deficient in endogenous GA₃. The greatest stimulation of parameters studied was obtained in ovule culture with GA₃ + NAA. When GA₃ or GA₃ + NAA was applied, initial significant difference in water amount and seed size was nullified. Data presented in this study indicated that GA₃ regulates cell expansion through the water uptake by cotton seed.     

Effects of elevated CO<Subscript>2</Subscript> and/or O<Subscript>3</Subscript> on hormone IAA in needles of Chinese pine

This study examined the effects of season-long exposure of Chinese pine (Pinus tabulaeformis) to elevated carbon dioxide (CO₂) and/or ozone (O₃) on indole-3-acetic acid (IAA) content, activities of IAA oxidase (IAAO) and peroxidase (POD) in needles. Trees grown in open-top chambers (OTC) were exposed to control (ambient O₃, 55 nmol mol⁻¹ + ambient CO₂, 350 μmol mol⁻¹, CK), elevated CO₂ (ambient O₃ + high CO₂, 700 μmol mol⁻¹, EC) and elevated O₃ (high O₃, 80 ± 8 nmol mol⁻¹ + ambient CO₂, EO) OTCs from 1 June to 30 September. Plants grown in elevated CO₂ OTC had a growth increase of axial shoot and needle length, compared to control, by 20% and 10% respectively, while the growth in elevated O₃ OTC was 43% and 7% less respectively, than control. An increase in IAA content and POD activity and decrease in IAAO activity were observed in trees exposed to elevated CO₂ concentration compared with control. Elevated O₃ decreased IAA content and had no significant effect on IAAO activity, but significantly increased POD activity. When trees pre-exposed to elevated CO₂ were transferred to elevated O₃ (EC–EO) or trees pre-exposed to elevated O₃ were transferred to elevated CO₂ (EO–EC), IAA content was lower while IAAO activity was higher than that transferred to CK (EC–CK or EO–CK), the change in IAA content was also related to IAAO activity. The results indicated that IAAO and POD activities in Chinese pine needles may be affected by the changes in the atmospheric environment, resulting in the change of IAA metabolism which in turn may cause changes in Chinese pine’s growth. An erratum to this article can be found at     

Germination response of Arabian desert species to gibberellic acid and potassium nitrate seed treatment

Abstract

Desert plant species commonly use seed dormancy to prevent germination during unfavorable environmental conditions and thus increase the probability of seedling survival. Seed dormancy presents a challenge for restoration ecology, particularly in desert species for which our knowledge of dormancy regulation is limited. In the present study the effect of gibberellic acid (GA₃) and potassium nitrate (KNO₃) on seed dormancy release was investigated on eight Arabian desert species. Both treatments significantly enhanced the germination of most species tested. GA₃ was more effective than KNO₃ in enhancing germination percentage, reducing mean germination time and synchronizing the germination in most of the studied species. Light requirement during germination was species-specific, but in general the presence of light promoted germination more effectively when combined with KNO₃ and GA₃. The wide variation in dormancy and germination requirements among the tested species is indicative of distinct germination niches, which might assist their co-existence in similar habitat/environmental conditions. Seed pre-treatments that optimize germination in this habitat must therefore be assessed for individual species to improve the outcomes of ecological restoration.     

Effect of kinetin and GA3 on in vitro ovule embryo culture of Cucumis melo L.

The ability of Cucumis melo embryos of different ages to form plants in vitro was studied in order to rescue hybrid embryos between C. melo and Cucumis metuliferus. Plants were grown in a glasshouse at temperatures ranging from 15°CN-28°CD. Best results were obtained with ovule embryos excised 17 days after pollination. At this age, kinetin of 0.5 mg l^–1 was found optimal for culturing embryo development. Similar results were obtained with ovule embryos excised 14 days after pollination which cultured on 0.5 mg l^–1 kinetin with 0.5 mg l^–1 GA₃.     

3 beta,13-dihydroxylated C20 gibberellins from inflorescences of Rumex acetosa L

Using full scan GC-MS a wide range of gibberellins (GAs) was identified in the young inflorescences of the dioecious species Rumex acetosa L., consistent with the ubiquitous early 13-hydroxylation pathway in both male and female plants. In addition, R. acetosa is the first species in which all three 3beta,13-dihydroxylated C(20)-GAs-GA(18), GA(38) and GA(23)-have been identified in the same organism, suggesting an early 3beta,13-dihydroxylation biosynthesis pathway in this species. Authentic GA(18), GA(38) and GA(23) were synthesized and their effects and that of GA(1), a GA common to both pathways, on the time to inflorescence emergence was investigated. GA(1) accelerated the emergence of inflorescences in both male and female plants. In addition some evidence for biological activity per se of the C(20)-GA(38) was obtained.