Vetiver (Vetiveria zizanioides L.) plants are able to protect the soil from erosion and are tolerant of salinity stress. However, at high salinity levels, vetiver plants show a decreasing growth. The ...application of gibberelin is expected to increase the growth of vetiver in salinity stress conditions. The purpose of this study was to evaluate the growth responsiveness and production of vetiver the application of gibberelin under salinity stress conditions. This research was conducted in the green house of the Faculty of Agiculture, Universitas Sumatera Utara, Medan. This study used a non-factorial completely randomized design, namely the salinity stress (S) which consisted of 3 levels, each treatment was repeated 3 times, so that 9 treatment combinations were obtained: the concentration of gibberelin was 0 (no treatment), 50 ppm and 100 ppm.
Drought-responsive element binding (DREB) is involved in the regulation of stress-responsive gene expressions in plants through abscisic acid (ABA)-independent pathway. In this study, constitutive ...expression of oil palm (Elaeis guineensis) EgDREB1 driven by double strength cauliflower mosaic virus 35S promoter in tomato (Solanum lycopersicum) reduced seed number, produced parthenocarpic fruits, changed morphology of leaves, and increased root biomass of transgenic plants. Early flowering and fruiting of the transgenic lines were observed in the culture vessels. EgDREB1 was specifically expressed in the fruits and its expression was not detected in vegetative tissues (leaves and roots). Altered expression of several endogenous tomato genes involved in the biosynthesis of phytohormones including jasmonic acid, ethylene, auxin, cytokinin, gibberellin (GA) and ABA were observed compared to wild type plants. The expression of AP2-like-ethylene transcription factor (LeAP2), allene oxide synthase (LeAOS), allene oxide cyclase (LeAOC), aminocyclopropane-1-carboxylic acid synthase (LeACS), 1-aminocyclopropane-1-carboxylate oxidase 1 (LeACO), auxin responsive factor 8 (LeARF8), auxin/indole-3-acetic acid (LeAux/IAA), cytokinin oxidase/dehydrogenase-like (LeSlCKX1), adenylate isopentenyltransferase (LeSlIPT1), gibberellin 2-oxidase 2 (LeGa2ox2), gibberellin 20-oxidase 4 (LeGa20ox4) and ABA-aldehyde oxidase (LeAAO) were different in fruits with reduced seed number compared to parthenocarphic fruits. These results suggest that their expression has significant effects on fruit development in transgenic tomato. EgDREB1 may mediate the expression of some of these genes as dehydration-responsive element binding (DRE) motif were found in their promoter sequences. These data indicate that the EgDREB1 controls fruit development in trsngenic plants by regulating the expression of hormone-associated genes.
The use of plant growth regulators is one effective solution to improve sugarcane yields and sugar content in several countries. In this study, we examined the role of gibberellin acid (GA3) and ...glyphosate (Gly) plant growth regulators to determine the appropriate concentration of GA3 and Gly to increase the yield of sugarcane and sugar accumulation, respectively. The statistical results showed that GA3 was sprayed at 150 ppm to increment the actual yield by 19.94%; sucrose accumulation increased by 2.21%. With Gly treatment, although the yield decreased by 3.17%, sucrose accumulation increased by 11.27% compared to control trials. In this study, the combined concentration of 150 ppm of both GA3 and Gly gave the best results, for which sucrose accumulation increased from 2.21% to 10.74% and from 19.94% to 20.97% for actual yield. The results led to increased net income compared to the control. To address concerns about residues of plant growth regulators, residues of GA3 and Gly were evaluated after the sugarcane harvest using the HPLC and UV-vis methods, respectively. The analyzed results showed that their residues were lower than what is permitted in several countries. This showed the applicability of the study, on a large scale, to increase sucrose accumulation, productivity of sugarcane, and profit for farmers.
The balance of gibberellins gibberellic acid (GA) and abscisic acid (ABA) is a determining factor during transition of embryogenesis and seed germination. Recently, we showed that 14-3-3 proteins are ...important in ABA signalling in barley aleurone cells. Using 14-3-3 RNAi constructs in the barley aleurone transient expression system, we demonstrate here that silencing of each 14-3-3 isoform suppresses GA induction of the α-amylase gene. 14-3-3 Proteins interact with ABA-responsive element (ABRE) binding factors HvABF1, 2 and 3, and here we show that these transcription factors also interact with the ABA-responsive kinase PKABA1, a kinase that mediates cross-talk between the GA and ABA pathway. ABF1 and ABF2 have a function in both signalling pathways as: (1) ectopic expression of wild-type ABF1 and mutant ABF2, lacking the 14-3-3 interaction domain, transactivates the ABA inducible HVA1 gene; and (2) GA induction of the α-amylase gene is repressed by ectopic expression of wild-type ABF1 and 2. Mutant ABF1 and 2 were still effective repressors of GA signalling. In summary, our data provide evidence that 14-3-3 proteins and members of the ABF transcription factor family have a regulatory function in the GA pathway and suggest that PKABA1 and ABF transcription factors are cross-talk intermediates in ABA and GA signalling.
Conduziu-se este trabalho, com o objetivo de avaliar a propagação sexuada e assexuada de Pfaffia glomerata (ginseng brasileiro). As sementes foram pré-embebidas por 24 horas em KNO3 1%; ácido ...giberélico 50, 100 e 200 mg L-1 ; emágua e as sementes que não receberam tratamento serviram como testemunha. A semeadura foi em placas de petri sobre duas folhas de papel de filtro e a incubação a 25ºC, sob iluminação constante e na ausência de luz. As estacas com º15 cm foram imersas durante 6 horas em IAA 250 e IBA 500 mg L-1, ácido bórico 1% e em água e plantadas em embalagem plástica, contendo terra+areia (1:1). O primeiro experimento foi conduzido em delineamento inteiramente casualizado em esquema fatorial 2 (níveis de luz) x 6 (tratamento de pré-embebição) em 4 repetições de 20 sementes. O segundo em DIC com 5 tratamentos, 4 repetições de 15 estacas por repetição. As sementes de ginseng brasileiro necessitam de tratamento de pré-embebição para acelerar a germinação, sendo a imersão em KNO3 o método mais eficiente, proporcionando 63% de germinação. Apresentam fotoblastismo neutro, com germinação média de 45%. As estacas de ginseng brasileiro imersas apenas em água apresentaram 100% de enraizamento, maior número de brotos (2,5) e maior comprimento de raiz (8,6 cm). A espécie apresenta potencial para ambos os métodos de propagação.
A new method for determination of gibberelin has been developed, based on the formation of a fluorescent compound with perchloric acid at 100 °C for 6 min. The maximum excitation and emission ...wavelengths of the fluorescent compound are 416 nm and 457 nm, respectively. Gibberelin in the range 10–800 ng ml
−1 can be determined; the 3σ detection limit is 5 ng ml
−1. The recommended method is very sensitive, selective, simple and rapid, making it ideal for the routine determination of gibberelin. The fluorescence reaction mechanism is discussed.
Conduziu-se este trabalho, com o objetivo de avaliar a propagação sexuada e assexuada de Pfaffia glomerata (ginseng brasileiro). As sementes foram pré-embebidas por 24 horas em KNO3 1%; ácido ...giberélico 50, 100 e 200 mg L-1 ; emágua e as sementes que não receberam tratamento serviram como testemunha. A semeadura foi em placas de petri sobre duas folhas de papel de filtro e a incubação a 25ºC, sob iluminação constante e na ausência de luz. As estacas com º15 cm foram imersas durante 6 horas em IAA 250 e IBA 500 mg L-1, ácido bórico 1% e em água e plantadas em embalagem plástica, contendo terra+areia (1:1). O primeiro experimento foi conduzido em delineamento inteiramente casualizado em esquema fatorial 2 (níveis de luz) x 6 (tratamento de pré-embebição) em 4 repetições de 20 sementes. O segundo em DIC com 5 tratamentos, 4 repetições de 15 estacas por repetição. As sementes de ginseng brasileiro necessitam de tratamento de pré-embebição para acelerar a germinação, sendo a imersão em KNO3 o método mais eficiente, proporcionando 63% de germinação. Apresentam fotoblastismo neutro, com germinação média de 45%. As estacas de ginseng brasileiro imersas apenas em água apresentaram 100% de enraizamento, maior número de brotos (2,5) e maior comprimento de raiz (8,6 cm). A espécie apresenta potencial para ambos os métodos de propagação.The objective of this study was to evaluate sexual and asexual propagation of Pfaffia glomerata (Brazilian Ginseng). The seeds were pre-soaked for 24 hours in KNO3 1% , gibberellic acid 50, 100, 200 mg L-1 , and in water. Untreated seeds served as control. Sowing was accomplished in petri dishes on 2 sheets of filter paper, at 25ºC incubation, under constant illumination, and in the absence of light. The cuttings with º1,5 cm were immersed for 6 hours in IAA 250 and 500mg L-1, boric acid1% ,and in water. Soon after they were planted in plastic containers with soil + sand (1:1). The first experiment was in factorial design 2 (light levels) x 6 (pre-soak treatment) in 4 repetitions of 20 seeds per repetition. The second in ERD in 5 treatments, 4 repetitions of 15 cuttings per repetition. Brazilian Ginseng seeds need pre-soak treatment to accelerate germination. We found immersion in KNO3 the most efficient method, providing 63% germination. They presented neuter photoblastism with an average germination of 45%. The Brazilian Ginseng cuttings immersed in water presented 100% rooting, a higher number of sprouts (2,5), and greater length (8,6 cm). The species presents potential for both propagation methods.
We have characterized potato (Solanum tuberosum L.) plants expressing a soybean leghemoglobin that is targeted to plastids. Transgenic plants displayed a dwarf phenotype caused by short internode ...length, and exhibited increased tuberization in vitro. Under in vivo conditions that do not promote tuberization, plants showed smaller parenchymal cells than control plants. Analysis of gibberellin (GA) concentrations indicated that the transgenic plants have a substantial reduction (approximately 10-fold) of bioactive GA₁ concentration in shoots. Application of GA₃ to the shoot apex of the transformed plants completely restored the wild type phenotype suggesting that GA-biosynthesis rather than signal transduction was limiting. Since the first stage of the GA-biosynthetic pathway is located in the plastid, these results suggest that an early step in the pathway may be affected by the presence of the leghemoglobin.
Sementes selecionadas escarificadas de canafístula foram submetidas a estresses hídricos simulados, sob 27°C, com ou sem a adição de poliaminas e giberelina. Os valores de porcentagem e velocidade de ...germinação obtidos com os testes realizados indicaram que as sementes são resistentes ao estresse hídrico, e a adição de putrescina e espermidina nas concentrações de 5 e 10mM aumenta a performance sob estresse hídrico. O uso de giberelina permite a ampliação do limite máximo de tolerância ao estresse hídrico.
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