Interrelations between Gibberellic Acid, Cytokinins and Abscisic Acid in Retarding Leaf Senescence

Somatic embryogenesis was induced in callus previously initiated from immature embryos of barley. These cultures ranged in age from 6 weeks to 30 months. Embryoids were readily initiated from homogenized suspension-grown aggregates when plated on modified B5 media with 2,4-dichlorophenoxyacetic acid. Low concentrations (0.1 and 0.05 mg∙L−1) of abscisic acid promoted further maturation of embryoids, while gibberellic acid (1 mg∙L−1) and kinetin (0.1 mg∙L−1) were used in the media to encourage embryoid germination. The development of somatic embryoids from initiation through maturation and germination is described.

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Endogenous hormonal content during grain development in hexaploid and tetraploid wheat

Bangladesh Journal of Agricultural Research ◽

10.3329/bjar.v33i3.1608 ◽

1970 ◽

Vol 33 (3) ◽

pp. 493-502 ◽

Cited By ~ 3

Author(s):

Sridhar Gutam ◽

Virendra Nath ◽

GC Srivastava

Keyword(s):

Growth Rate ◽

Acetic Acid ◽

Abscisic Acid ◽

Gibberellic Acid ◽

Grain Growth ◽

Indole Acetic Acid ◽

Tetraploid Wheat ◽

Weight Basis ◽

Ploidy Levels ◽

Hormonal Content

A pot experiment was conducted in the rabi (post rainy) seasons of 2001 and 2002 to study the genotypic differences in grain growth rate and endogenous hormonal content in the developing grains of hexaploid and tetraploid wheat. The endogenous hormonal contents of grains in both the ploidy levels had changed in sequence. At 5 days after anthesis (DAA), gibberellic acid (GA3); at 15 DAA (rapid growth phase), indole-acetic acid (IAA); at 25 DAA (dough stage), abscisic acid (ABA) were maximum. At 35 DAA, all the endogenous hormonal level decreased and among the hormones, ABA was highest followed by IAA and GA3. Hexaploids recorded higher concentrations of endogenous hormones (13.38% IAA, 17.89% GA3, and 14.7% ABA) on fresh weight basis and resulted in higher seed weight (56.99 mg/grain) and grain growth rate (0.009 g/g/day) compared to tetraploids (49.08 mg/grain; 0.008 g/g/day) on dry weight basis by better mobilization of photosynthates during grain filling. Key Words: Grain growth rate, hormones, indole-acetic acid, gibberellic acid, abscisic acid. doi:10.3329/bjar.v33i3.1608 Bangladesh J. Agril. Res. 33(3) : 493-502, September 2008

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Arabidopsis SIGMA FACTOR BINDING PROTEIN1 (SIB1) and SIB2 inhibit WRKY75 function in abscisic acid-mediated leaf senescence and seed germination

Journal of Experimental Botany ◽

10.1093/jxb/erab391 ◽

2021 ◽

Cited By ~ 1

Author(s):

Haiyan Zhang ◽

Liping Zhang ◽

Yunrui Ji ◽

Yifen Jing ◽

Lanxin Li ◽

...

Keyword(s):

Abscisic Acid ◽

Seed Germination ◽

Leaf Senescence ◽

Chromatin Immunoprecipitation ◽

Sigma Factor ◽

Dependent Manner ◽

Negative Regulators ◽

Factor Binding ◽

Physiological Processes ◽

Increased Sensitivity

Abstract The plant-specific VQ gene family participates in diverse physiological processes but little information is available on their role in leaf senescence. Here, we show that the VQ motif-containing proteins, Arabidopsis SIGMA FACTOR BINDING PROTEIN1 (SIB1) and SIB2 are negative regulators of abscisic acid (ABA)-mediated leaf senescence. Loss of SIB1 and SIB2 function resulted in increased sensitivity of ABA-induced leaf senescence. In contrast, overexpression of SIB1 significantly delayed this process. Moreover, biochemical studies revealed that SIBs interact with WRKY75 transcription factor. Loss of WRKY75 function decreased sensitivity to ABA-induced leaf senescence, while overexpression of WRKY75 significantly accelerated this process. Chromatin immunoprecipitation assays revealed that WRKY75 directly binds to the promoters of GOLDEN 2-LIKE1(GLK1) and GLK2, to repress their expression. SIBs repress the transcriptional function of WRKY75 and negatively regulate ABA-induced leaf senescence in a WRKY75-dependent manner. In contrast, WRKY75 positively modulates ABA-mediated leaf senescence in a GLK-dependent manner. In addition, SIBs inhibit WRKY75 function in ABA-mediated seed germination. These results demonstrate that SIBs can form a complex with WRKY75 to regulate ABA-mediated leaf senescence and seed germination.

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Induction of Dormancy in Nondormant Seeds

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.119.3.408 ◽

1994 ◽

Vol 119 (3) ◽

pp. 408-413 ◽

Cited By ~ 9

Author(s):

Anwar A. Khan

Keyword(s):

Abscisic Acid ◽

Lycopersicon Esculentum ◽

Gibberellic Acid ◽

Lactuca Sativa ◽

Daucus Carota ◽

Apium Graveolens ◽

Lettuce Seeds ◽

Moist Chilling ◽

Dormancy Induction ◽

Ga Biosynthesis

A gibberellic acid (GA) biosynthesis inhibitor, tetcyclacis, induced dormancy in nondormant seeds of lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), pepper (Capsicum annuum L.), carrot [Daucus carota var. sativus (Hoffn.)], onion (Allium cepa L.), celery (Apium graveolens L.), and impatiens (Impatiens novette), as most of the seeds failed to germinate after washing under conditions that permitted germination before dormancy induction. In lettuce seeds, tetcyclacis and paclobutrazol were more effective in inhibiting germination in light than in darkness. A 16- to 24-h soak treatment with tetcyclacis was sufficient to induce dormancy in nearly all seeds. Tetcyclacis failed to induce dormancy if applied after 6 h presoak in water. Dormancy induced by tetcyclacis was released by GA4+7 (a mixture of gibberellin A4 and A7), light, and moist-chilling treatments. When GA4+7 was applied with tetcyclacis, dormancy induction was prevented under both favorable, e.g., 25C, and unfavorable, e.g., 5C, or low water potential (Ψ), germination conditions. Unlike tetcyclacis, abscisic acid (ABA) failed to induce dormancy in lettuce seeds. Thermodormancy induction in lettuce seeds at 35C was prevented by fluridone. However, neither ABA nor tetcyclacis countered its effect. Dormancy was also induced in lettuce seeds by ancymidol, flurprimidol, or paclobutrazol. Dormancy induced by tetcyclacis in pepper, tomato, carrot, and onion seeds was released by GA4+7, but not by irradiation or moist-chilling. Chemical names used: 5-(4-chlorophenyl)-3, 4, 5, 9, 10-pentaazatetracyclo [5.4.102,6.08,11]-dodeca-3, 9-diene (tetcyclacis); 1-(4-chlorophenyl)-4, 4-dimethyl-2-(1H-1, 2, 4-triazole-1-yl)-3-pentanol (paclobutrazol); α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidine methanol (ancymidol); α-(1-methyl)-α-[4-(trifluoromethoxy) phenyl]-5-pyrimidine-methanol (flurprimidol); 1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4 (1H)-pyridinone (fluridone).

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Gibberellic acid, paclobutrazol, fluoridone, abscisic acid affecting flowering and fruit set of coffee

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v89i3-4.1037 ◽

1969 ◽

Vol 89 (3-4) ◽

pp. 159-168

Author(s):

Carlos A. Flores ◽

Winston De la Torre ◽

Miguel Monroig ◽

Wigmar González

Keyword(s):

Abscisic Acid ◽

Gibberellic Acid ◽

Coffea Arabica ◽

Fruit Set ◽

Late Development ◽

Flower Bud ◽

Initial Reduction ◽

Coffea Arabica L

Applications of gibberellic acid (GA), paclobutrazol and gibberellic acid (Paclo/GA), fluoridone and gibberellic acid (FL/GA), and abscisic acid (ABA) were made to synchronize flowering in coffee trees (Coffea arabica L.). Overall growth of trees and branches was not affected by the treatments. Production of new leaves was not affected by the treatments. However, the Paclo/GA treatment tended to increase the production of secondary branches. Flower bud production was affected by the ABA treatment during the first three weeks, showing an initial reduction in number and a late development of buds. Plants receiving the GA treatment produced more flowers during the first week of evaluation as well as a higher number and greater weight of mature fruits during the first week of harvesting.

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