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At least 163 records · Page 9Linked to original sources
PubMed1977

Influence of Plant Hormones on Ethylene Production in Apple, Tomato, and Avocado Slices during Maturation and Senescence.

Ethylene production by tissue slices from preclimacteric, climacteric, and postclimacteric apples was significantly reduced by isopentenyl adenosine (IPA), and by mixtures of IPA and indoleacetic acid, and of IPA, indoleacetic acid, and gibberellic acid after 4 hours of incubation. Ethylene production by apple (Pyrus malus L.) slices in abscisic acid was increased in preclimacteric tissues, decreased in climacteric peak tissues, and little affected in postclimacteric tissues. Indoleacetic acid suppressed ethylene production in tissues from preclimacteric apples but stimulated ethylene production in late climacteric rise, climacteric, and postclimacteric tissue slices. Gibberellic acid had less influence in suppressing ethylene production in preclimacteric peak tissue, and little influenced the production in late climacteric rise, climacteric peak, and postclimacteric tissues. IPA also suppressed ethylene production in pre- and postclimacteric tissue of tomatoes (Lycopersicon esculentum) and avocados (Persea gratissima). If ethylene production in tissue slices of ripening fruits is an index of aging, then IPA would appear to retard aging in ripening fruit, just as other cytokinins appear to retard aging in senescent leaf tissue.

Journal Article↗
PubMed1984

Effect of plant hormones on sucrose uptake by sugar beet root tissue discs.

Abscisic acid (ABA), auxins, cytokinins, gibberellic acid, alone or in combination were tested for their effects on short-term sucrose uptake in sugar beet (Beta vulgaris cv USH-20) roots. The effect of ABA on active sucrose uptake varied from no effect to the more generally observed 1.4-to 3.0-fold stimulation. A racemic mixture of ABA and its trans isomer were more stimulatory than ABA alone. Pretreating and/or simultaneously treating the tissue with K(+) or IAA prevented the ABA response while cytokinins and gibberellic acid did not. While the variable sensitivities of beet root to ABA may somehow be related to the auxin and alkali cation status of the tissue, tissue sensitivity to ABA was not correlated with ABA uptake, accumulation, or metabolic patterns. In contrast to ABA, indoleacetic acid (IAA) and other auxins strongly inhibited active sucrose uptake in beet roots. Cytokinins enhanced the auxin-induced inhibition of sucrose uptake but ABA and gibberellic acid did not modify or counteract the auxin effect. Trans-zeatin, benzyladenine, kinetin, and gibberellins had no effect on active sucrose uptake. None of the hormones or hormone mixtures tested had any significant effect on passive sucrose uptake. The effects of IAA and ABA on sucrose uptake were detectable within 1 h suggesting a rather close relationship between the physiological activities of IAA and ABA and the operation of the active transport system.

Journal Article↗
PubMed1985

Seed Germination in Chenopodium album L: Relationships between Nitrate and the Effects of Plant Hormones.

Effects of ethylene, gibberellins, and kinetin on the germination of two lots of Chenopodium album L. seeds, collected from the field in 1982 and 1983, were studied in relation to the availability of nitrate. The experiments were conducted in darkness and at temperatures ranging from 12 to 32 degrees C. Ethylene induced over 75% germination in the 1983 seed but had little effect on the 1982 seed. Nitrate was only slightly promotive in either of the two seed lots. A combination of ethylene and nitrate, however, acted synergistically on 1982 seed, resulting in as much germination as that induced in 1983 seed by ethylene alone. In 1983 seed, a combination of ethylene and nitrate was only marginally more effective than ethylene. A similar relationship was observed in the effects of gibberellic acid(4+7) (GA(4+7)) and nitrate on seeds from the two lots. The 1982 seed, which responded synergistically to combinations of nitrate with ethylene or GA(4+7) was found to contain an extremely low endogenous level of nitrate as compared to 1983 seed. Thus, high levels of either endogenous or applied nitrate appeared to enhance the germination response to ethylene or GA(4+7).Kinetin had no effect on 1982 seed and only a small promotive effect on 1983 seed. There was no synergism between kinetin and nitrate in either of the seed lots.

Journal Article↗
PubMed1988

Plant hormone interaction and phenolic metabolism in the regulation of russet spotting in iceberg lettuce.

Russet spotting (RS) is a physiological disorder induced in iceberg lettuce (Lactuca sativa L.) by exposure to parts per million levels of ethylene at 5 +/- 2 degrees C. Ethylene induced phenylalanine ammonia-lyase and ionically bound peroxidase activities that correlated with development of RS symptoms. The ethylene-treated tissue had significantly higher lignin content than air control tissue with lignification localized in walls of RS-affected cells. Ethylene also caused the accumulation of the flavonoids (+)catechin and (-)epicatechin and the chlorogenic acid derivatives 3-caffeoyl-quinic acid, 3,5-dicaffeoylquinic acid, and 4,5-dicaffeoylquinic acid. These soluble phenolic compounds were readily oxidized to brown substances by polyphenol oxidase isolated from RS tissue. Ethylene substantially increased ionically bound indole-3-acetic acid (IAA) oxidase activity, while IAA application greatly reduced ethylene-induced phenylalanine ammonia-lyase, peroxidase, and IAA oxidase activities, soluble phenolic content, and RS development.

Journal Article↗
PubMed1977

Effects of treatment with the plant hormone gibberellin on neonatal rats.

Treatment of neonatal rats with a single does of gibberellin had a notable influence on certain endocrine indices in adulthood. It accelerated the growth rate of the animals and produced weight increase of thyroid, ovary and adrenals as well as of the blood Ca-level, but reduced the weight of the testis.

Adrenal Glands↗
PubMed1995

Effect of simulated microgravity on auxin polar transport in inflorescence axis of Arabidopsis thaliana.

The morphology, growth and development of higher plants are strongly influenced by environmental stimuli on the earth, which affect the changes in the dynamics of plant hormones in plants. Qualitative and quantitative changes in plant hormones are the most important internal factor to regulate plant growth and development. Among them, auxin (IAA) is of most significant. There are numerous reports concerning the physiological roles of auxin in plant growth and development (Matthysse and Scott 1984). One of the characteristics of auxin is to have the ability of polar transport along the vector of gravity on the earth (Schneider and Wightman 1978), suggesting that the activity of auxin polar transport is also important for the growth and development of plants. It has recently been reported that the normal activity of auxin polar transport in inflorescence axis of Arabidopsis thaliana was required for flower formation (Okada et al. 1991, Ueda et al. 1992). Considering the above evidence together with the fact that gravity affects the morphology, growth and development of higher plants, gravity might affect the qualitative and quantitative changes in plant hormones including the activity of auxin polar transport. In this paper, we report the effect of microgravity condition simulated by a three-dimensional (3-D) or a horizontal clinostat on the activity of auxin polar transport in inflorescence axis of Arabidopsis thaliana.

Arabidopsis↗
PubMed2006

Dwarfism and cytochrome P450-mediated C-6 oxidation of plant steroid hormones.

BRs (brassinosteroids) are plant steroid hormones that are essential for normal plant development. The dramatic dwarfism exhibited by mutants in the CYP (cytochrome P450) enzymes involved in BR biosynthesis indicates a role for these hormones in plant growth and development. Since the mid-1990s, collaborative research has been geared towards developing a better understanding of the CYP85 class of CYPs involved in BR biosynthesis in both Arabidopsis and tomato. Some of the most recent observations include the fact that certain CYP85 CYPs catalyse the synthesis of the most bioactive BR, BL (brassinolide). Current evidence suggests that evolution of this function may have occurred independently in different dicotyledonous species. Interestingly, BL accumulates in tomato fruits, highlighting a key role for this hormone in fruit development. At the same time as developing a better understanding of the enzymatic function of these CYPs, we have also carried out experiments towards characterizing where and when these genes are expressed and mechanisms of their regulation. As expected for a hormone involved in growth and development, biosynthetic gene promoter activity is associated with young rapidly growing cells and with fruit development.

Arabidopsis↗
PubMed2005

Plant brassinosteroid hormones.

In animals, a large number of steroid hormones play important roles in numerous processes including reproduction and differentiation. The biologically active plant steroid brassinolide (BL) was first discovered in the pollen of western rape in 1979 (Grove et al., 1979). This finding suggested that BL is indispensable for plant growth and differentiation. To date, more than 50 BL analogs have been identified, and the group has been termed brassinosteroids (BRs) (Fujioka and Yokota, 2003). Brassinosteroids have several biological activities, such as inducing cell elongation when applied at very low concentrations. For this reason, soon after their discovery, they were suggested to be a sixth type of plant hormone; however, for years BRs were not considered true plant hormones. The turning point in BR research was the discovery of the Arabidopsis dwarf mutants det2 and cpd in 1996 (Li et al., 1996; Szekeres et al., 1996). These BR-deficient mutants were found to revert to the wild-type phenotype following BR treatment. Concurrent with the analysis of these mutants, an outline of the biosynthetic pathway of BRs was being elucidated through chemical analysis. Following the isolation of det2 and cpd, a great number of BR-deficient mutants were identified. The mutant genes were found to encode proteins that catalyze the conversion of plant steroids to BR precursors. Eventually, BRs were widely recognized as important plant hormones indispensable for growth and differentiation (Clouse and Sasse, 1998). In parallel, mutants that are insensitive to BRs were isolated (Clouse et al., 1996; Li et al., 1997) with phenotypes very similar to those of the BR-biosynthesis mutants. Investigations of these mutants revealed several mechanisms of BR perception and signal transduction (Bishop and Koncz, 2002; Clouse, 2002). This review describes findings on the effects of BRs on plant growth, BR biosynthesis and catabolism, and BR signal transduction.

Brassinosteroids↗
PubMed2000

Manipulation of hormone biosynthetic genes in transgenic plants.

Modification of plant hormone biosynthesis through the introduction of bacterial genes is a natural form of genetic engineering, which has been exploited in numerous studies on hormone function. Recently, biosynthetic pathways have been largely elucidated for most of the plant hormone classes, and genes encoding many of the enzymes have been cloned. These advances offer new opportunities to manipulate hormone content in order to study their mode of action and the regulation of their biosynthesis. Furthermore, this technology is providing the means to introduce agriculturally useful traits into crops.

Cyclopentanes↗
PubMed2004

[Studies on sex identification and variation of endogenous hormones in female and male plants of Gynostemma pentaphyllum].

OBJECTIVE: To distinguish female and male plants of Gynostemma pentaphyllum quickly and accurately in the stage of seedling and to understand the relation between sex differentiation and endogenous plant hormone. METHOD: Stained methods of BTB and enzyme linked immuno-sorbent Assay were used. RESULT: 10 Hours after being dyed, the liquid extract of female plants turned into yellow, while extract of male ones turned green. There were obvious differences on iPAs and GA(1 + 3) contents but no differences on IAA and ABA contents between male and female plants during the stages of seedling and vegetative growth. CONCLUSION: BTB can be used for distinguishing female and male plants and there were a certain relation between sex and endogenous plant hormones.

Gibberellins↗
PubMed2002

Cloning the tomato curl3 gene highlights the putative dual role of the leucine-rich repeat receptor kinase tBRI1/SR160 in plant steroid hormone and peptide hormone signaling.

Brassinosteroids (BRs) are plant steroid hormones that are essential for normal plant development. To gain better understanding of the conservation of BR signaling, the partially BR-insensitive tomato mutant altered brassinolide sensitivity1 (abs1) was identified and found to be a weak allele at the curl3 (cu3) locus. BR content is increased in both of these mutants and is associated with increased expression of DWARF: The tomato homolog of the Arabidopsis Brassinosteroid Insensitive1 Leu-rich repeat (LRR) receptor-like kinase, named tBri1, was isolated using degenerate primers. Sequence analysis of tBRI1 in the mutants cu3 and abs1 revealed that cu3 is a nonsense mutant and that abs1 is a missense mutant. A comparison of BRI1 homolog sequences highlights conserved features of BRI1 sequences, with the LRRs in close proximity to the island domain showing more conservation than N-terminal LRRs. The most homologous sequences were found in the kinase and transmembrane regions. tBRI1 (SR160) also has been isolated as the putative receptor for systemin, a plant peptide hormone. This finding suggests a possible dual role for tBRI1 in steroid hormone and peptide hormone signaling.

Alleles↗
PubMed2005

Mammalian sex hormones in plants.

The occurrence of mammalian sex hormones and their physiological role in plants is reviewed. These hormones, such as 17beta-estradiol, androsterone, testosterone or progesterone, were present in 60-80% of the plant species investigated. Enzymes responsible for their biosynthesis and conversion were also found in plants. Treatment of the plants with sex hormones or their precursors influenced plant development: cell divisions, root and shoot growth, embryo growth, flowering, pollen tube growth and callus proliferation. The regulatory abilities of mammalian sex hormones in plants makes possible their use in practice, especially in plant in vitro culture.

Animals↗