Showing papers on "Gibberellic acid published in 2002"
TL;DR: Results indicated that the heterologous Arabidopsis CBF1 can confer water deficit resistance in transgenic tomato plants.
Abstract: A DNA cassette containing an Arabidopsis C repeat/dehydration-responsive element binding factor 1 (CBF1) cDNA and a nos terminator, driven by a cauliflower mosaic virus 35S promoter, was transformed into the tomato (Lycopersicon esculentum) genome. These transgenic tomato plants were more resistant to water deficit stress than the wild-type plants. The transgenic plants exhibited growth retardation by showing dwarf phenotype, and the fruit and seed numbers and fresh weight of the transgenic tomato plants were apparently less than those of the wild-type plants. Exogenous gibberellic acid treatment reversed the growth retardation and enhanced growth of transgenic tomato plants, but did not affect the level of water deficit resistance. The stomata of the transgenic CBF1 tomato plants closed more rapidly than the wild type after water deficit treatment with or without gibberellic acid pretreatment. The transgenic tomato plants contained higher levels of Pro than those of the wild-type plants under normal or water deficit conditions. Subtractive hybridization was used to isolate the responsive genes to heterologous CBF1 in transgenic tomato plants and the CAT1 (CATALASE1) was characterized. Catalase activity increased, and hydrogen peroxide concentration decreased in transgenic tomato plants compared with the wild-type plants with or without water deficit stress. These results indicated that the heterologous Arabidopsis CBF1 can confer water deficit resistance in transgenic tomato plants.
419 citations
TL;DR: The proteomic analysis indicated that GAs do not participate in many processes involved in germination sensu stricto (prior to radicle protrusion), as well as the initial mobilization of seed protein and lipid reserves, while two isoforms of S-adenosyl-methionine synthetase, which catalyzes the formation of Ado-Met from Met and ATP, might represent a major metabolic control of seedling establishment.
Abstract: We examined the role of gibberellins (GAs) in germination of Arabidopsis seeds by a proteomic approach. For that purpose, we used two systems. The first system consisted of seeds of the GA-deficient ga1 mutant, and the second corresponded to wild-type seeds incubated in paclobutrazol, a specific GA biosynthesis inhibitor. With both systems, radicle protrusion was strictly dependent on exogenous GAs. The proteomic analysis indicated that GAs do not participate in many processes involved in germination sensu stricto (prior to radicle protrusion), as, for example, the initial mobilization of seed protein and lipid reserves. Out of 46 protein changes detected during germination sensu stricto (1 d of incubation on water), only one, corresponding to the cytoskeleton component α-2,4 tubulin, appeared to depend on the action of GAs. An increase in this protein spot was noted for the wild-type seeds but not for the ga1 seeds incubated for 1 d on water. In contrast, GAs appeared to be involved, directly or indirectly, in controlling the abundance of several proteins associated with radicle protrusion. This is the case for two isoforms of S -adenosyl-methionine (Ado-Met) synthetase, which catalyzes the formation of Ado-Met from Met and ATP. Owing to the housekeeping functions of Ado-Met, this event is presumably required for germination and seedling establishment, and might represent a major metabolic control of seedling establishment. GAs can also play a role in controlling the abundance of a β-glucosidase, which might be involved in the embryo cell wall loosening needed for cell elongation and radicle extension.
289 citations
TL;DR: Two recent reports have indicated that RGL1 and RGL2, both homologous to the GA-response height-regulating factors GAI/RGA/RHT/d8/SLR1/SLN1, are repressors of seed germination in Arabidopsis, providing new clues as to how GA controls seeds germination.
196 citations
TL;DR: Results indicate that aquaporins in the root, especially the RsPIP2 group, may be a stress responsive type of aquaporin at least in the protein level.
Abstract: Aquaporins in the plasma and vacuolar membranes play a key role in the intercellular and intracellular water transport in plants. First, we quantitated the absolute amounts for mRNAs of eight aquaporin isoforms in hypocotyls of radish seedlings. Then, we investigated the effects of salt and water stresses (150 mM NaCl, 300 mM mannitol and 20% polyethylene glycol) and phytohormones (gibberellic acid, abscisic acid and brassinolide) on the mRNA and protein levels of aquaporins in the plasma membrane (RsPIP1-1, 1-2, 1-3, 2-1, 2-2 and 2-3) and vacuolar membrane (RsTIP1-1 and 2-1). The mRNA and protein levels of RsTIP1-1, RsTIP2-1, RsPIP1-1, RsPIP1-2 and RsPIP1-3 were comparatively constant. In contrast, mannitol treatment altered the mRNA levels of RsPIP2-1, RsPIP2-2 and RsPIP2-3 in roots. Immunoblot analysis showed that the RsPIP2-1 protein level was increased by NaCl treatment and decreased by treatment with mannitol and polyethylene glycol. Gibberellic acid and abscisic acid suppressed the levels of mRNAs of RsPIP2-1, RsPIP2-2 and RsPIP2-3 and the protein level of RsPIP2-1 in roots. On the other hand, the protein levels of RsPIP1-group members and RsTIPs were scarcely changed by these phytohormones. In the case of hypocotyls and cotyledons, the mRNA and protein levels of eight isoforms were not markedly affected by any treatment. These results indicate that aquaporins in the root, especially the RsPIP2 group, may be a stress responsive type of aquaporin at least in the protein level.
152 citations
TL;DR: Overall, gibberellic acid treatment stimulated the vegetative growth of both cultivars ofwheat under salt stress, but it caused a slight reduction in grain yield.
Abstract: A sand culture experiment assessed whether gibberellic acid(GA3) could alleviate the adverse effects of salt stress on thegrowth, ion accumulation and photosynthetic capacity of two spring wheatcultivars, Barani-83 (salt sensitive) and SARC-I (salt tolerant).Three-week-oldplants of both cultivars were exposed to 0, 100 and 200 molm−3 NaCl in Hoagland's nutrient solution. Threeweeks after the initiation of salt treatments, half of the plants of eachcultivar were sprayed overall with 100 mg L−1GA3 solution. Plants were harvested 3 weeks after theapplication of GA3. Fresh and dry weights of shoots and roots, plantheight and leaf area were decreased with increasing supply of salt, butgibberellic acid treatment caused a significant ameliorative effect on both thecultivars with respect to these growth attributes. However, GA3caused no significant change in grain yields but increased grain size in boththe cultivars. Saline growth medium caused a marked increase in theconcentrations of Na+ and Cl− in shoots androots of both the lines. However, with the application of GA3accumulation of Na+ and Cl− was enhanced inboth shoots and roots of both wheat lines, but more ions accumulated in saltsensitive Barani-83 than in salt tolerant SARC-1. Net CO2assimilation rate (A) of both wheat lines decreased consistently withincreasingsupply of NaCl, but application of GA3 alleviated the effect of saltstress on this variable in both the cultivars. However, the ameliorative effectof the hormone was more pronounced in Barani-83 than in SARC-1. Althoughwater-use efficiency (A/E = CO2assimilation/transpiration) and intrinsic water use efficiency(A/gs = CO2 assimilation/stomatalconductance) decreased significantly with increasing salt concentration of thegrowth medium in both the cultivars, GA3 was more effective inenhancing both the water-use attributes in Barani-83 than in SARC-1. Overall,GA3 treatment stimulated the vegetative growth of both cultivars ofwheat under salt stress, but it caused a slight reduction in grain yield.GA3 treatment enhanced the accumulation of Na+ andCl− in both shoots and roots of wheat plants under saltstress.It also caused a significant increase in photosynthetic capacity in both linesat the vegetative stage under both saline and non-saline media.
135 citations
TL;DR: The temporal, spatial and hormonal regulation pattern of LeXET4 gene expression suggests that XET has a role in endosperm cap weakening, a key process regulating tomato seed germination.
Abstract: Xyloglucan endotransglycosylases (XETs) modify xyloglucans, major components of primary cell walls in dicots. A cDNA encoding an XET (LeXET4) was isolated from a germinating tomato (Lycopersicon esculentum Mill.) seed cDNA library. DNA gel blot analysis showed that LeXET4 is a single-copy gene in the tomato genome. LeXET4 mRNA was strongly expressed in germinating seeds, was much less abundant in stems, and was not detected in roots, leaves or flower tissues. During germination, LeXET4 mRNA was detected in seeds within 12 h of imbibition with maximum mRNA abundance at 24 h. Tissue prints showed that LeXET4 mRNA was localized exclusively to the endosperm cap region. Expression of LeXET4 was dependent on exogenous gibberellin (GA) in GA-deficient (gib-1 mutant) tomato seeds, while abscisic acid, a seed germination inhibitor, had no effect on LeXET4 mRNA expression in wild-type seeds. LeXET4 mRNA disappeared after radicle emergence, even though degradation of the lateral endosperm cell walls continued. The temporal, spatial and hormonal regulation pattern of LeXET4 gene expression suggests that XET has a role in endosperm cap weakening, a key process regulating tomato seed germination.
128 citations
TL;DR: Results suggest that tomato α-Afs are encoded by a gene family under differential hormonal controls, and probably have different in vivo functions.
Abstract: α-l-Arabinofuranosidases (α-Afs) are plant enzymes capable of releasing terminal arabinofuranosyl residues from cell wall matrix polymers, as well as from different glycoconjugates. Three different α-Af isoforms were distinguished by size exclusion chromatography of protein extracts from control tomatoes (Lycopersicon esculentum) and an ethylene synthesis-suppressed (ESS) line expressing an antisense 1-aminocyclopropane-1-carboxylic synthase transgene. α-Af I and II are active throughout fruit ontogeny. α-Af I is the first Zn-dependent cell wall enzyme isolated from tomato pericarp tissues, thus suggesting the involvement of zinc in fruit cell wall metabolism. This isoform is inhibited by 1,10-phenanthroline, but remains stable in the presence of NaCl and sucrose. α-Af II activity accounts for over 80% of the total α-Af activity in 10-d-old fruit, but activity drops during ripening. In contrast, α-Af III is ethylene dependent and specifically active during ripening. α-Af I released monosaccharide arabinose from KOH-soluble polysaccharides from tomato cell walls, whereas α-Af II and III acted on Na2CO3-soluble pectins. Different α-Af isoform responses to gibberellic acid, synthetic auxins, and ethylene were followed by using a novel ESS mature-green tomato pericarp disc system. α-Af I and II activity increased when gibberellic acid or 2,4-dichlorophenoxyacetic acid was applied, whereas ethylene treatment enhanced only α-Af III activity. Results suggest that tomato α-Afs are encoded by a gene family under differential hormonal controls, and probably have different in vivo functions. The ESS pericarp explant system allows comprehensive studies involving effects of physiological levels of different growth regulators on gene expression and enzyme activity with negligible wound-induced ethylene production.
63 citations
TL;DR: A distinct lack of correlation between the effect ofJA-Me on inhibition of flowering and shoot and root growth was noted, which indicates the independent action of JA-Me in controlling both processes.
Abstract: The effect of methyl jasmonate (JA-Me) on the floral bud formation and elongation growth in the short-day plant Pharbitis nil was investigated. The placing of 4-day-old seedlings of P. nil in a solution of JA-Me for a period of 24 h before an inductive (16 h or 14 h of darkness) night led to a dramatic reduction in the number of flower buds formed by the plant. Plants treated with JA-Me also totally lost their capacity to form a generative terminal bud. JA-Me applied after photoinduction does not inhibit flowering. Gibberellic acid (GA3) partly reverses the inhibitory effect of JA-Me. Plants treated simultaneously with JA-Me and GA3 formed about 3 flower buds more than plants treated with JA-Me only. JA-Me at a concentration of 10-7 M stimulates slightly, but at higher concentrations it inhibits root growth and shoot growth. A distinct lack of correlation between the effect of JA-Me on inhibition of flowering and shoot and root growth was noted. This indicates the independent action of JA-Me in controlling both processes.
62 citations
Journal Article•
TL;DR: In this article, the levels of endogenous free, bound and total auxin (Indole-3-acetic acid, IAA), gibberellic acid (GA3), abscisic acid(ABA) and cytokinin (zeatin) were examined in some species of mosses and lichens.
Abstract: In this study, the levels of endogenous free, bound and total auxin (Indole-3-acetic acid, IAA), gibberellic acid (GA3), abscisic acid (ABA) and cytokinin (zeatin) were examined in some species of mosses and lichens. For determination of the levels of these plant growth regulators, spectrophotometry was used. Our findings show that the mosses and lichens used in this study produce the plant growth regulators IAA, GA3, ABA and zeatin.
58 citations
TL;DR: Four genotypes of sweet cherry producing fruits characterized as early season/soft texture (`Merpet'), earlySeason/firm texture ( `Celeste'), late season/ soft texture (13S-27-17) and late season /firmtexture (`Lapins') were evaluated for differences in fruit growth, firmness, and hydrolytic enzyme activity with or without gibberellic acid treatment.
Abstract: SummaryFour genotypes of sweet cherry (Prunus avium L.) producing fruits characterized as early season/soft texture (`Merpet'), early season/firm texture (`Celeste'), late season/soft texture (13S-27-17) and late season/firm texture (`Lapins') were evaluated for differences in fruit growth, firmness, and hydrolytic enzyme activity with or without gibberellic acid treatment. The fruit developed in three distinct stages after fertilization corresponding to the standard Prunus profile (i.e. cell division, lag phase, cell enlargement). Fruits on early maturing genotypes had a shortened period in the lag phase compared to the late maturing cultivars. Fruit firmness in all genotypes increased from the earliest green-coloured stage (about 5.mm in fruit diameter) until the middle of the lag phase, then decreased rapidly and continuously from that stage throughout maturation. Application of 20 mg l-1 GA3 increased fruit firmness at harvest, decreased the rate of fruit softening and delayed fruit maturity 5±8.d for...
52 citations
TL;DR: It is indicated that high gibberellin doses induce more rapid floral initiation than lower doses and play a role in floral development.
Journal Article•
TL;DR: Results indicate that the induction of dormancy in embryos is a promising application for synthetic seed production and reduced chances of embryo survival during long-term desiccation were distinctly delayed in dormant embryos.
Abstract: In most plants, somatic embryos tend to germinate prematurely, a process that is detrimental to controlled plant production and the conservation of artificial seeds. We investigated the dormancy characteristics of Siberian ginseng somatic embryos induced simply by a high sucrose treatment, a treatment that enables the long-term conservation of artificial seeds following encapsulation and provides embryos with an enhanced resistance to dehydration. Early-cotyledonary stage somatic embryos were mass-produced by means of bioreactor culture. These embryos were then plated on medium supplemented with various levels of sucrose (1%, 3%, 6% or 9%) and allowed to mature. Subsequent germination of these embryos following the maturation period depended significantly on the sucrose level. At concentrations of 9% sucrose, none of the somatic embryos germinated after maturation, and none were recovered after being transferred to half-strength MS medium containing 2% sucrose. Gibberellic acid treatment was necessary to induce germination; other growth regulators such as auxins and cytokinins did not induce a response. Endogenous abscisic acid content in somatic embryos matured at 9% sucrose (487.8 ng/g FW) was approximately double that found in those matured at 3% sucrose (258.4 ng/g FW). This indicates induced dormancy in embryos under high osmotic stress. Alginate encapsulation of embryos facilitated the artificial induction of dormancy to extend the conservation period without germination. The induction of dormancy strengthened resistance to dehydration after the embryos were desiccated to 15% of their normal water content. Reduced chances of embryo survival during long-term desiccation were distinctly delayed in dormant embryos. These results indicate that the induction of dormancy in embryos is a promising application for synthetic seed production.
TL;DR: All seeds of Aeluropus lagopoides and Urochondra setulosa germinated under non-saline conditions except for Sporobolus ioclados which showed only 40 % germination.
Abstract: All seeds of Aeluropus lagopoides and Urochondra setulosa germinated under non-saline conditions except for Sporobolus ioclados which showed only 40 % germination Increase in salinity substantially inhibited germination and few seeds germinated at 400 mM NaCl Germination at 200 mM NaCl was alleviated in U setulosa by the application of gibberellic acid and fusicoccin, in A lagopoides by thiourea, betaine, kinetin, fusicoccin and ethephon, and in S ioclados by gibberellin and ethephon High salinity (400 mM NaCl) induced germination inhibition was alleviated by proline, kinetin, fusicoccin and ethephon only in A lagopoides
01 Jan 2002
TL;DR: In this article, Fusarium oxysporum was found to produce both gibberellin (GA) and indole-acetic acid (IAA) and the optimum period for GA and IAA was 10 days in mycelium and 15 days in filtrate at 28 °C.
Abstract: Rhizosphere and rhizoplane of fababean (Vicia faba), melochia (Corchorus olitorius), sesame (Sesamum indicum) and soyabean (Glycine max) plants are inhabited with fungi, mostly Aspergillus flavus, A. niger, Fusarium oxysporum, Penicillium corylophilum, P. cyclopium, P. funiculosum and Rhizopus stolonifer. All fungal species have the ability to produce gibberellin (GA) but F. oxysporum was found to produce both GA and indole-acetic acid (IAA). The optimum period for GA and IAA production by F. oxysporum was 10 days in the mycelium and 15 days in the filtrate at 28 °C. The contents of GA, IAA and cytochrome P-450 were increased at 0.5 and 1% NaCl after 5 days, but GA and IAA were lowered at 4% (700 mM) NaCl. Calcium decreased NaCl stress on F. oxysporum by significant elevating GA biosynthesis at 40mM Ca2+/700 mM Na+. GA at 10 mM and Ca2+ at 10 mM enhanced the germination of seeds under 175 mM Na+.
TL;DR: The influence of temperature/photoperiod treatment and gibberellic acid concentration (0, 0.1 or 1.0 mg/l) on direct conversion of microspore-derived embryos (MDEs) to plantlets of winter oilseed rape was investigated and observations on morphological development of MDEs showed clear differences in reaction at various temperature/Photoperiod treatments.
Abstract: The influence of temperature/photoperiod treatment and gibberellic acid concentration (0, 0.1 or 1.0 mg/l) on direct conversion of microspore-derived embryos (MDEs) to plantlets of winter oilseed rape was investigated. Physiologically mature, 21-day-old MDEs were transferred to a solid B5 medium supplemented with gibberellic acid, and cultured at 24 °C, 4 °C or 1 °C for 14 days, and then at 24 °C for the next 21 days. Low temperature was linked with short photoperiod (8 h light/16 h dark), and high temperature was linked with long photoperiod (16 h light/8 h dark). The highest embryo conversion rate was at 1 °C with over 70%, compared to<20% at 4 °C. Two-way analysis of variance confirmed the significance of the effect of temperature/photoperiod treatment. By contrast, gibberellic acid concentration had no significant effect on stimulation of shoot development from apical meristems of MDEs. Roots developed from apical root meristems of MDEs very easily. The best obtained conversion rate of MDEs induced with cold treatment at1 °C for 14 days was 86.5%. Observations on morphological development of MDEs showed clear differences in reaction at various temperature/photoperiod treatments.
TL;DR: Results indicate that gibberellin A3, applied during the induction as well as the differentiation stage, reduced the weight of callus and increased the number ofomatic embryos in Medicago sativa L tissue cultures.
Abstract: The influence of exogenous gibberellic acid (GA3) andpaclobutrazol, an inhibitor of gibberellin biosynthesis, on growth of callusandsomatic embryogenesis in petiole-derived tissue cultures of Medicagosativa L. has been investigated. GA3 (0.5–500μM) or paclobutrazol(5–100 μM) were added to either an induction (with 2,4 Dand kinetin) or a differentiation medium (without plant growth regulators).Gibberellin A3, applied during the induction as well as thedifferentiation stage, reduced the weight of callus and increased the number ofsomatic embryos in Medicago sativa L. tissue cultures.Somatic embryo production was increased more by the presence of exogenousGA3 in the differentiation than induction medium. The inclusion ofpaclobutrazol in the induction or differentiation medium caused the inhibitionof callus growth and embryo production. Callus growth was much less affectedthan embryogenesis. These results indicate that gibberellins are beneficial forboth embryoinduction and formation. The level of endogenous gibberellins is presumablysufficient for callus induction and growth. However, it seems not optimal forthe induction and particularly for the differentiation of embryos.
TL;DR: Calli grown from segments of spinach root in the presence of gibberellic acid plus auxin differentiated to yield somatic embryos after transfer to a medium without growth regulators, while calli formed in the absence of GA3 failed to generate any embryos.
Abstract: Calli grown from segments of spinach (Spinacia oleracea L) root in the presence of gibberellic acid (GA3) plus auxin, differentiated to yield somatic embryos after transfer to a medium without growth regulators, while calli formed in the absence of GA3 failed to generate any embryos We extracted proteins from the two types of callus and analysed them by polyacrylamide gel electrophoresis Compared with the proteins from calli formed on medium that contained only naphthaleneacetic acid (NAA) as a growth regulator, the proteins from calli grown in the presence of GA3 included appreciably higher levels of a 31-kDa basic protein (pI = 88) The protein resembled type I ribosome-inactivating proteins (EC 32222) in terms of molecular mass, isoelectric point, sequence of amino-terminal amino acids and extent of glycosylation The 31-kDa protein was barely detectable in extracts of various tissues from seedlings Thus, it is possible that an increase in the relative level of this protein might be associated with the expression of embryogenic potential expressed by spinach callus
TL;DR: This study found that secondary and repetitive somatic embryogenesis, which is rarely reported in monocots, was observed in common bermudagrass (Cynodon dactylon, cv. ‘Savannah’), and a full course of such a development was captured by a periodical microphotography.
Abstract: Bermudagrass is an important warm-season turfgrass species that is recalcitrant in regeneration in tissue culture. In a previous report, we observed that somatic embryogenesis of immature inflorescence culture was substantially improved when low levels of 2,4-dichloro-phenoxy acetic acid (1 mg/l) and 6-benzylaminopurine (BAP, 0.01 mg/l) were included in the callus induction medium. The object of this study was to further improve the culture conditions to enhance somatic embryo formation and plantlet regeneration. It was shown that the abscisic acid supplement (2 or 5 mg/l) to the above callus induction medium further enhanced somatic embryogenesis in hybrid bermudagrass (Cynodon dactylon×Cynodon transvaalensis) cv. ‘Tifgreen’. The addition of gibberellic acid (0. 2 mg/l) to the BAP (1 mg/l)-containing regeneration medium accelerated germination/regeneration of the somatic embryos. Secondary and repetitive somatic embryogenesis, which is rarely reported in monocots, was observed in common bermudagrass (Cynodon dactylon, cv. ‘Savannah’), and a full course of such a development was captured by a periodical microphotography. Scanning electron microscopy further confirmed the observation.
TL;DR: Eryngium foetidum L. plants were regenerated from mature leaf and petiole explants through direct organogenesis without intervening callus phase and showed 70.9% survival in the field.
Abstract: Eryngium foetidum L. plants were regenerated from mature leaf and petiole explants through direct organogenesis without intervening callus phase. From leaf explants, adventitious multiple shoots raised on Murashige and Skoog (MS) medium supplemented with 4.43 μM benzylaminopurine (BAP) and 0.57 μM indole-3-acetic acid (IAA), whereas in petiole explants shoot regeneration occurred at 8.86 μM BAP and 0.57 μM IAAA. 80% of the leaf explants and 44% of petiole explants produced shoots after four weeks of culture. The regenerated plants were rooted on MS medium supplemented with 2.46 μM indole-3-butyric acid and 2.88 μM gibberellic acid. The plants were successfully established in the soil and showed 70.9% survival in the field.
TL;DR: The results suggest that LA and ABA bind to the same receptor in higher plants and can explain why LA has ABA-like activity inHigher plants.
Abstract: Lunularic acid (LA) inhibited not only the germination and the growth of cress and lettuce at 1 mM but also the gibberellic acid (GA3)-induced α-amylase induction in embryoless barley seeds at 120 μM, which was recognized as a specific activity of abscisic acid (ABA). Moreover LA and ABA equally inhibited the growth of Lunularia cruciata A18 strain callus at 40 and 120 μM. A computational analysis revealed that the stable conformers of LA could be superimposed on the stable ABA conformers. In addition, the antibody raised against the conjugate of C1-ABA-bovine serum albumin (ABA-BSA) reacted with LA-horse-radish peroxidase (LA-HRP) conjugate as well as ABA-HRP conjugate, apparently. These results can explain why LA has ABA-like activity in higher plants. Moreover the results suggest that LA and ABA bind to the same receptor in higher plants.
Journal Article•
TL;DR: It was noted that all the three growth regulators used in the present study were able to overcome to variable extents the adverse effects of stress imposed by NaCl solution.
Abstract: Efficiency of pretreatment as foliar spray of indole-3-acetic acid, gibberellic acid and kinetin (6-furfuryl aminopurine) each ranging from 10(-7) to 10(-5) M in restoring the metabolic alterations imposed by NaCl salinity (E.C. value 4.0 m mhos/cm) was investigated in Vigna radiata (L.) Wilczek. Application of NaCl resulted in about 7% and 9% decrease in phenol content in mung bean leaf and root respectively. In leaf, NaCl caused 40% increase in polyphenol oxidase enzyme activity over the control set. This effect was accentuated in root, where salinity caused 200% increase in the enzyme activity. In leaf and root of mung-bean plant, ascorbic acid content decreased about 29% and 31% respectively under salinity stress as compared with control. Ascorbic acid oxidase enzyme activity increased under stress by about 55% and 23% respectively in leaf and root. It was noted that all the three growth regulators used in the present study were able to overcome to variable extents the adverse effects of stress imposed by NaCl solution.
TL;DR: In this article, the development of cotton fibre was divided into four distinct growth phases but overlap between elongation and secondary thickening was considerable which suggests that both these phases are independent of each other.
Abstract: Fibres of three cotton cultivars (Gossypium hirsutum H-4, H-8 and G. arboreum G. Cot-15) were analysed for growth in terms of fibre length and dry weight and endogenous gibberellic acid (GA 3 ) content thrice during 1997-2000, at Rajkot. The development of cotton fibre was divided into four distinct growth phases but overlap between elongation and secondary thickening was considerable which suggests that both these phases are independent of each other. During fibre elongation, GA 3 content remained low and increased after a decrease in the rate of fibre elongation in all three genotypes. The long staple cultivar (H-4) showed highest endogenous GA 3 content followed by the middle one (H-8) and the short staple cultivar (G. Cot-15). In in vitro studies when GA 3 , NAA or GA 3 + NAA was supplemented to the media, increase in fibre length of the short staple cultivar was maximum, followed by the middle one and the long staple cultivar. Both in vivo and in vitro findings suggest that GA 3 is one of the important factors that determine fibre length.
TL;DR: It is shown that it is possible to propagate Helleborus niger by means of in vitro cloning by using Universal (U) medium, which was created by Haensch as a universal medium to meet the average nutritional requirements of many different plants.
Abstract: This study shows that it is possible to propagate Helleborus niger by means of in vitro cloning. Universal (U) medium has been used for the in vitro culture. This medium was created by Haensch as a universal medium to meet the average nutritional requirements of many different plants. Apical buds of H. niger seedlings were established on U-medium supplemented with 8.9 µmol/l 6-benzylaminopurine (BAP) and 2.7 µmol/l α-naphthaleneacetic acid. Propagation was carried out on U-medium supplemented with 2.2 µmol/l BAP and 2.9 µmol/l gibberellic acid. The highest rooting success rate of 96.7% was achieved by adding 4.9 µmol/l indole-3-butyric acid to the medium. Shooting and rooting were dependent on the seedling cloned. More than 80% of the in vitro plants survived and thrived in the greenhouse.
TL;DR: Regeneration of Plumbago rosea L., a rare medicinal plant, via somatic embryogenesis in callus cultures derived from leaf explants was described, and 50 – 60 plantlets were obtained from 150 mg of embryogenic callus within 4 week of subculture.
Abstract: Regeneration of Plumbago rosea L., a rare medicinal plant, via somatic embryogenesis in callus cultures derived from leaf explants was described. Optimum callus formation was achieved on semi-solid Murashige and Skoog (MS) medium supplemented with 0.25 mg dm−3 kinetin and 2.0 mg dm−3 1-naphthaleneacetic acid (NAA). Somatic embryogenesis was achieved upon transferring the 4-week-old callus to a medium containing 1.0 mg dm−3 kinetic (Kn), 0.5 mg dm−3 gibberellic acid (GA3) and 0.1 mg dm−3 NAA. Embryo maturation and germination was achieved on the half-strength MS basal salts supplemented with 0.01 – 0.25 mg dm−3 Kn and 2 % (m/v) saccharose. An average of 50 – 60 plantlets were obtained from 150 mg of embryogenic callus within 4 week of subculture. Out of the 50 plantlets about 28 survived in the greenhouse.
TL;DR: The effect of plant growth regulators on the pathogenic fungus Sclerotinia sclerotiorum (white mould) was investigated under in vitro and in vivo conditions and methyl jasmonate, and abscisic acid decreased mycelium growth in vitro.
Abstract: The effect of plant growth regulators on the pathogenic fungus Sclerotinia sclerotiorum (white mould) was investigated under in vitro and in vivo conditions. Naphthalene acetic acid inhibits the fungus in vitro and in vivo.It reduced white mould disease severity on bean and cucumber plants at concentrations of 200–400 lg/ml.Gibberellic acid (GA 3) promoted both mycelium and white mould disease severity on plants at concentrations of 50–250 lg/ml.Methyl jasmonate (MeJa), and abscisic acid (ABA) decreased mycelium growth of S. sclerotiorum in vitro.MeJa decreased bean and cucumber white mould disease at concentrations of 75–250 lg/ml.ABA increased disease development on bean and cucumber plants at concentrations of 100–300 lg/ml.
TL;DR: Hairy roots of spinach obtained by inoculation of cotyledon explants with wild-type Agrobacterium rhizogenes A13 yielded regenerated plantlets with actively growing root systems and shoots that did not bolt.
TL;DR: Results suggest that this medium, called K22, containing 0.5 mg l–1 TDZ and 0.04 mg IAA, shows good shoot-generating capacity with all four species of the genus Kalanchoë, and has a high regenerative capacity within the Crassulaceae.
Abstract: SummaryFour species of the genus Kalanchoe (Crassulaceae), K. peltata, K. laxiflora, K. tubiflora and K. marmorata, were regenerated from leaf explants by direct organogenesis. Each species was tested on 19 media, all based on MS-medium. One medium was without growth regulators, the remaining 18 contained a combination of auxin and cytokinin. Auxin was indole-3-acetic acid (IAA): 1.1, 2.3 or 4.6 μM (0.2, 0.4 or 0.8 mg l–1). Cytokinin was either 1-phenyl-3-(1,2,3-thidiazol-5-yl)urea(TDZ): 1.1, 2.3 or 4.5 μM (0.25, 0.5 or 1.0 mg l–1), or 6-benzylaminopurine (BAP): 1.1, 2.2 or 4.4 μM (0.25, 0.5 or 1.0 mg l–1). For each species an optimum level of growth regulators were obtained. One medium, called K22, containing 0.5 mg l–1 TDZ and 0.04 mg l–1 IAA, showed good shoot-generating capacity with all four species. Shoot elongation proved to be a problem only with K. marmorata. This could be bypassed by transferring shoots to a gibberellic acid (GA3)-containing medium, or by ventilating the containers. Shoots were ...
TL;DR: In this article, anaerobic conditions appeared to break a mild post-harvest dormancy in this rice cultivar, and 95% germination was achieved by germinating the seeds anaerobically, either in a pure N2 environment or submerged in unstirred tap water.
Abstract: Dwarf plants are useful in research because multiple plants can be grown in a small area. Rice (Oryza sativa L.) is especially important since its relatively simple genome has recently been sequenced. We are characterizing a gibberellic acid (GA) mutant of rice (japonica cv 'Shiokari,' line N-71) that is extremely dwarf (20 cm tall). Unfortunately, this GA mutation is associated with poor germination (70%) under aerobic conditions. Neither exogenous GA nor a dormancy-breaking heat treatment improved germination. However, 95% germination was achieved by germinating the seeds anaerobically, either in a pure N2 environment or submerged in unstirred tap water. The anaerobic conditions appear to break a mild post-harvest dormancy in this rice cultivar. Copyright 2002 Crop Science Society of America.
Journal Article•
TL;DR: Results indicated that hardness and impermeability of seed coats to water uptake might be the most important cause of the dormancy present in seeds of C. clusii, C. monspeliensis and C. salvifolius.
Abstract: Different pretreatments for promoting germination of Cistus clusii, C. monspeliensis and C. salvifolius, Cistaceous species widely distributed in Mediterranean region, were investigated. Pretreatments applied were: dry-heat, seed soaking in distilled water and gibberellic acid. Germination tests were performed under controlled conditions at 15°C in darkness. Dry-heat treatments were shown to break dormancy. The highest germination percentages in the three species studied were obtained with dry-heat at 100°C for five minutes. Dry-heat at 80°C for a longer exposition times was only effective for C. clusii and C. salvifolius. These results indicated that hardness and impermeability of seed coats to water uptake might be the most important cause of the dormancy present in seeds of C. clusii, C. monspeliensis and C. salvifolius, as in other Cistus species. The soaking of seeds in distilled water and exogenous gibberellic acid applications did not significantly increase germination over untreated seeds.