Showing papers on "Gibberellic acid published in 1977"
TL;DR: The results demonstrate that the balance between abscisic acid on the one hand and zeatin and gibberellic Acid on the other can effectively control somatic embryo development and either disrupt or ensure normal maturation.
Abstract: The effects of abscisic acid, zeatin, and gibberellic acid on the development of somatic embryos from cultured cells of caraway ( Carum carvi L.) were observed. Somatic embryos complete development on a basal medium without exogenous hormones, but some are subject to developmental abnormalities including malformed cotyledons and accessory embryos. Both zeatin and gibberellic acid, especially in combination, stimulate growth and increase the frequency of aberrant forms. Zeatin causes the formation of multiple shoots, leafy and abnormal cotyledons, and in the dark, enlarged hypocotyls; gibberellic acid effects root elongation, polycotyledony, and some callus formation. In contrast, abscisic acid, at concentrations which do not inhibit embryo maturation, selectively suppresses abnormal proliferations. With abscisic acid, and especially in the dark, a high percentage of embryos complete development with two fleshy cotyledons on unelongated axes free of accessory embryos. In the light, zeatin eliminates abscisic acid inhibition while gibberellic acid only partially counters its effect, promoting elongated radicles and green rather than white cotyledons. In the dark, zeatin in combination with abscisic acid stimulates extensive callusing. Gibberellic acid does not reverse the effects of abscisic acid but rather enhances them and can counter the disruptive effects of zeatin. The results demonstrate that the balance between abscisic acid on the one hand and zeatin and gibberellic acid on the other can effectively control somatic embryo development and either disrupt or ensure normal maturation.
140 citations
TL;DR: The results suggest that the effect of desiccation in changing leaf hormonal make-up is related to a mechanism designed to curtail water loss under conditions inducing water deficiency.
Abstract: The interrelationship between water deficiency and hormonal makeup in plants was investigated in detached leaves of romaine lettuce ( Lactuca sativa L. cv. `Hazera Yellow9). Water stress was imposed by desiccating the leaves for several hours in light or darkness at different air temperatures and relative humidity. In the course of desiccation, a rise in abscisic acid content and a decline in gibberellin and cytokinin activity were observed by gas-liquid chromatography, by both the barley endosperm bioassay and radioimmunoassay and by the soybean callus bioassay. Gibberellin activity began to decline in the stressed leaves before the rise in abscisic acid, the rate of this decline being positively correlated with the rate of increase in leaf water saturation deficit. Recovery from water stress was effected by immersing the leaf petioles in water while exposing the blades to high relative humidity. This resulted in a decrease in leaf water saturation deficit, a reduction in abscisic acid content, and an increase in gibberellin and cytokinin activity. Application of abscisic acid to the leaves caused partial stomatal closure in turgid lettuce leaves, whereas treatment with gibberellic acid and kinetin of such leaves had no effect on the stomatal aperture. In desiccating leaves, however, gibberellic acid and kinetin treatment considerably retarded stomatal closure, thus enhancing the increase in leaf water saturation deficit. These results suggest that the effect of desiccation in changing leaf hormonal make-up, i.e. a rapid increase in abscisic acid and a decrease in both cytokinin and gibberellin activity, is related to a mechanism designed to curtail water loss under conditions inducing water deficiency.
77 citations
TL;DR: Although S. europaea is the most salt tolerant of the species growing on the salt pan in which it occurs, an increase in salinity stress proved to be inhibitory to seed germination for all temperature regimes investigated.
67 citations
TL;DR: Preliminary data suggest that a K + activated ATPase present in membrane preparation is involved in the mechanism of active K + uptake in the seeds.
62 citations
TL;DR: It appears that the free sugars of the female gametophyte, namely sucrose, raffinose, and stachyose and their monosaccharide constituents, are the best substrates for growth and polysaccharide synthesis.
Abstract: Pine pollen (Pinus mugo) grown in suspension cultures readily utilize exogenous carbohydrates for tube growth and starch synthesis: these processes are not influenced by β-indolylacetic acid, gibberellic acid, kinetin and abscisic acid. It appears that the free sugars of the female gametophyte, namely sucrose, raffinose, and stachyose and their monosaccharide constituents, are the best substrates for growth and polysaccharide synthesis. The oligosaccharides are hydrolysed to their monosaccharide constituents before they are taken up. A preferential uptake of fructose is noted. Non-metabolizable sugars are not taken up. The data presented establish that tube growth, except for the initial growth phase, can be determined by the availability of exogenous carbohydrates.
Measurements of some of the key enzymes in carbohydrate metabolism show that the enzymes were present in the ungerminated pollen grain, and that the enzyme activity increased severalfold during tube growth. The increase in enzyme activity was prevented if inhibitors of protein synthesis were present in the medium.
51 citations
TL;DR: Plants were regenerated from axillary shoot tips of 12 Andean potato clones chosen to cover the full range of ploidies from 2X to 5X, and one European tuberosum clone to show that roots were formed and could be readily established in soil.
48 citations
TL;DR: Kinetin and ethylene, as demonstrated primarily in the thermodormancy at 36 C and in osmotic dormancy, appear to regulate a common event(s) leading to germination but through mechanisms unique to each respective growth regulator.
Abstract: The germination of lettuce seeds (Lactuca sativa L., cv. Premier Great Lakes) was significantly inhibited by high temperature (32 C), 0.1 mM abscisic acid or 0.4 M mannitol. Ethylene (16 μl/1 of air) partially reversed the dormancy induced by all three inhibitors but only in the presence of 1 mM gibberellic acid (GA) or light. Neither ethylene plus GA nor ethylene plus light were able to promote germination when thermal inhibition was imposed at 36 C. Addition of 0.01 mM kinetin to the ethylene plus GA or light reversed thermodormancy at 36 C. The dormancy imposed by abscisic acid was also reversed by kinetin. Kinetin was unable to reverse the osmotic dormancy imposed by mannitol. The reversal of osmotic dormancy by ethylene or ethylene plus GA was actually inhibited by kinetin but only in the light. Kinetin apparently stimulates cotyledonary growth in the presence of light, and this growth may compete for certain metabolites critical to radicle growth and subsequent germination. Kinetin and ethylene, as demonstrated primarily in the thermodormancy at 36 C and in osmotic dormancy, appear to regulate a common event(s) leading to germination but through mechanisms unique to each respective growth regulator. The regulation of germination by ethylene is absolutely dependent upon an interaction with GA and/or light.
47 citations
TL;DR: The hydrolysis of the xylans is largely caused by endoxylanase activity, indicating the importance of endoglycosidases in the GA3-induced breakdown of the aleurone cell wall.
Abstract: When aleurone layers of barley (Hordeum vulgare L.) are incubated with gibberellic acid (GA3) xylose and arabinose—both as free sugars and bound to larger molecules—are released into the medium. Release begins 10–12h after the start of incubation and continues for at least 60h. At the same time there is a GA3-induced breakdown of the cell wall resulting in a loss of 2/3 of the cell-wall pentose during 60h of incubation. GA3 causes the appearance in the medium of an enzyme (or enzymes) which hydrolyze larchwood xylan and aleurone-layer arabinoxylan. Release of the enzyme(s) into the medium begins 28–32h after the start of incubation. Enzyme activity does not accumulate to any large extent in the tissue prior to release into the medium, and is present in very low levels only in the absence of GA3. Xylanase activity is associated with a protein (or proteins) with a molecular weight of 29,000. The hydrolysis of the xylans is largely caused by endoxylanase activity, indicating the importance of endoglycosidases in the GA3-induced breakdown of the aleurone cell wall.
46 citations
TL;DR: It was apparent that reduced growth was associated with increased enzyme activity, probably due to an enhanced protein synthesis, and the activity of catalase, peroxidase, IAA oxidase, and ascorbic acid oxidase incresed in response to lead addition.
44 citations
TL;DR: Investigation of germination characteristics of Heteropogon contortus found that the dormancy factor apparently associated with these structures could not be detected when seed was germinated in soil in the glasshouse and it appeared that they are a necessary protection for the caryopsis under field conditions.
Abstract: Germination characteristics of Heteropogon contortus were investigated in germination cabinets and in the glasshouse using soil trays. Under the former a dual inhibitory system appeared to operate. On the one hand naked caryopses from seeds which were less than 4 months of age were inhibited from germination by a process apparently analogous to epicotyl dormancy. This could readily be broken by applying 1% gibberellic acid and partly broken by repeated wetting and drying. On the other hand between 4 and 12 months, naked caryopses germinated more readily than intact seeds (caryopsis plus glumes, lemmas, etc.). However, the dormancy factor apparently associated with these structures could not be detected when seed was germinated in soil in the glasshouse and it appeared that they are a necessary protection for the caryopsis under field conditions.
The optimal temperature for germination was between 30 and 35°C constant. Alternating diurnal temperatures of less than this appeared to cause reduced germination, and no high-temperature stimulation was observed. Germination was not directly promoted by the passage of a normal grass fire.
37 citations
TL;DR: It is concluded that colchicine does not inhibit the kinetics of cell growth or the deposi... changes in wall fibrils and microtubules are described.
Abstract: The effects of colchicine, singly and in combination with gibberellic acid (GA3), on growth of lettuce hypocotyl cells are reported. After 72 h of growth, the cells in GA3 are extremely long and cy...
TL;DR: Defoliation experiments showed that there was a flowering-inhibition by young leaves and it was suggested that the promotive effect of benzyladenine was mainly by redirecting the flow of assimilates, while gibberellic acid would stimulate, specifically, the development of floral parts.
TL;DR: Triadimefon retarded the elongation of the upper internodes of shoots of tomato and cotton plants and blocked ergosterol biosynthesis in Ustilago avenae, and strongly reduced the synthesis of gibberellin-like substances in Fusarium moniliforme.
Abstract: Triadimefon retarded the elongation of the upper internodes of shoots of tomato and cotton plants. The growth retardation was completely reversed by exogenously applied gibberellic acid (GA3). Growth of coleoptiles, primary leaves and roots of wheat and barley seedlings was reduced after seed treatment with triadimefon; application of GA3 did not completely counteract this growth retardation. Leaves of triadimefon-treated plants showed a darker green colour; leaves became lighter again when the growth retardation was reversed by GA3 application. When detached leaf sections were floated in triadimefon solutions or suspensions in the dark, senescence was delayed. The compound showed only a weak antagonistic effect on GA3-induced α-amylase synthesis in barley endosperm. Triadimefon strongly reduced the synthesis of gibberellin-like substances in Fusarium moniliforme. It inhibited the development of haustoria of Erysiphe graminis f. sp. hordei. Studies on its mode of action revealed that triadimefon blocked ergosterol biosynthesis in Ustilago avenae.
TL;DR: The data clearly demonstrate that the composition and activity of the photosynthetic ap paratus are under phytohormone control, and IAA and even better kinetin promote the light induced formation of pigment systems and electrontransport chains.
Abstract: The Hill-activity (reduction of DCPIP or methylviolgen) and the concentration of P700 were studied in chloroplasts isolated from cotyledons of radish seedlings (Raphanus sativus L. saxa Treib), which had been grown with the addition of beta-indoleacetic acid (IAA), kinetin, or gibberellic acid. 1) The photosynthetic activity of young chloroplasts from 3 day old Raphanus seedlings is very high (c. 180 micron mol O2/mol chlorophyll X h) and decreases continuously thereafter with increasing age. The steady state Hill-activity is reached after 8 to 10 days (values of 55 to 50 micron mol O2/mg chlorophyll X h). 2) Chloroplasts from plants treated with IAA or kinetin not only exhibit higher plastoquinone levels 1,2, but also a higher P700-content and a higher Hill-activity. The promotion effect is more pronounced with kinetin (+36 tb 40%) than with IAA (+12 to 17%). 3) Gibberellic acid has a different effect on composition and activity of chloroplasts. In younger seedlings the Hill-activity appears to be somewhat stimulated, without promotion effect on plastoquinone 2 or P700 concentration. After 10 days GA3-treated plants show signs of chlorosis combined with a strong decrease in photosynthetic activity. 4) The data clearly demonstrate that the composition and activity of the photosynthetic apparatus are under phytohormone control. IAA and even better kinetin promote the light induced formation of pigment systems and electrontransport chains. GA3 seems to block the rebuilding of the photosynthetic apparatus under steady state conditions.
TL;DR: The results are discussed in relation to the balance between fat and carbohydrate metabolism of the germinating seed and the importance of isocitrate lyase as a control point connecting the two aspects of this metabolism.
Abstract: SUMMARY
During germination the lipids, triglycerides and starch stored in the cotyledons of the ground nut are mobilized. The time course of this degradation has been measured and the accumulation of mono- and diglycerides, free fatty acids, phospholipids, cholesterol and sucrose has been estimated during the first 8 days of development. During this time the lipase and amylase activities present in the seeds increased. The lipase appeared to be relatively unspecific. A feature of germination was the induction of isocitrate lyase activity which was not present in the seed before germination. The action of gibberellic acid, abscisic acid and ethylene on germination, mobilization of reserves and enzyme induction had been studied.
Application of abscisic acid inhibited germination and also the increase in lipase activity. It also inhibited strongly the induction of isocitrate lyase, but it increased amylase activity and starch breakdown. The presence of the axis in the germinating seeds helps to restore normal metabolism when it is disturbed by the application of the exogenous growth substances.
The results are discussed in relation to the balance between fat and carbohydrate metabolism of the germinating seed and the importance of isocitrate lyase as a control point connecting the two aspects of this metabolism.
TL;DR: The purpose of this study was to determine if salt-conditioning seed pretreatments would be effective in increasing the salt tolerance of cottonseed, an important crop in many hot, arid environments where saline irrigation water is used.
Abstract: One factor which limits crop production in the arid Southwest is the high salinity of soils and irrigation waters; especially during germination and early growth. The purpose of this study was to determine if salt-conditioning seed pretreatments would be effective in increasing the salt tolerance of cottonseed. Effects of 11 seed pretreatments on cotton (Gossypium barbadense L.) germination under saline and nonsaline conditions were studied in the laboratory to determine their usefulness in increasing relative salt tolerance. Salts, phytohormones, and adenosine monophosphate were used in seed pretreatments and their effectiveness was tested by germinating the pretreated seeds in single and mixed salts of NaCl and CaCL. Several pretreatments hastened germination under salinity by at least 1 day over nontreated controls. However, soaking in distilled water enhanced germination under saline conditions as much as any other pretreatment. Using original seed weight to determine drying time of seeds after pretreatment was inadequate because of gains or losses of solute during the soaking cycle. Additional index words: Gossypium barbadense, Gibberellic acid, Kinetin, Indole acetic acid, Adenosine monophosphate. L ONG-STAPLE cotton (Gossypium barbadense L.) is an important crop in many hot, arid environments where saline irrigation water is used. We conducted this study to determine it various seed pretreatments, such as have been described with wheat (4, 11), could effectively increase the salt tolerance of a commercial variety of long-staple cotton. Cotton pretreatment has not been studied as extensively as that of wheat and, whereas grains are very salt tolerant during germination and more sensitive during seedling and later growth stages, cotton is sensitive during germination and more tolerant during the later growth stages (2). Sometimes, costly management practices can minimize soil salinity problems during early plant growth but in some areas saline irrigation waters make salt stress unavoidable. Thus, the potential value of pre1 Contribution from [he U. S. Salinity Lab., ARS, USDA P.O. Box 672, Riverside, CA 92502. Received 8 Aug. 1976. 2 Research agronomist and agronomist, respectively. conditioning seeds to increase germination and seedling development is apparent. Typically, soil salinity delays normal development of root and shoot extension at germination (1). Prolonging this critical growth period increases chances of seedling damage by pathogenic or environmental factors. Furthermore, critical storage reserves within the seed are slowly depleted, causing decreased seedling survival and vigor. A beneficial and desirable consequence of seed pretreatment would be to maintain normal germination rate in the presence of salt. In 1883, Will and de Saussure (as cited in 17) used soaking and drying as a seed pretreatment before planting to increase drought tolerance. This technique was applied to increase salt tolerance by pretreating seeds in salt solutions (9). Since these early studies, soaking seeds in solutions that contain salts (4, 10), phytohormones (7) and other chemicals (10) has had many effects on germination and subsequent plant growth and development. Among the beneficial effects noted have been increased germination (4, 10), more rapid radicle elongation (17), more extensive root systems (7), increased yields and greater drought (8), cold (5, 6), and salt resistance (11). In 1924, Toole and Driimmond (19) described prewetting of cottonseed for improving germination in dry climates or of hard seed. They did not dry the seeds and they attributed better germination to a higher seed moisture content. Genkel (8) reported that seed treatment with 3% NaCl (0.5 N) increased yields of wheat and cotton 15 to 30% when grown in chloride-salted soils. Similar results have been reported for CaCl2 pretreatments in increasing wheat germination in NaCl medium (4). At low salinities, germination improved even when seeds were dried after pretreatment (11). This is important and essential because seed usually must be dry to be sown by mechanical planters and drills. MATERIALS AND METHODS A commercial lot of long-staple 'Pima S-4' cottonseed was used for all experiments. The acid-delinted, fungicide-treated seed tested 85% germination based on official germination methods. Germinat ion tests were made on blotters soaked in the appropriate solutions and then placed under and over the seeds Published July, 1977
TL;DR: Partial purification of hydroxycinnamate: CoA ligase, and its properties in callus cells of Daucus carota L. have different phenylpropanoid pathways depending on the medium composition.
Abstract: Callus cells of Daucus carota L. have different phenylpropanoid pathways depending on the medium composition. Cells propagated on a medium with gibberellic acid do not accumulate cyanidin but incorporate [14C]phenylalanine into chlorogenic acid at a high rate. Cells grown on a medium free of gibberellic acid accumulate cyanidin in very large amounts. We here describe partial purification of hydroxycinnamate: CoA ligase, and its properties in these two cell lines. The enzymes extracted from the two cell populations had different substrate specifities: for that from anthocyanin-containing cells, p-coumaric acid was the best substrate, and caffeic acid and ferulic acid were also activated. With enzyme from anthocyanin-free cells, the lowest Km values were obtained for caffeic acid, while ferulic acid had higher values, and p-coumaric acid was nearly inactive. The enzyme did not separate into isoenzymes during purification. Only on polyacrylamide gels the partially purified enzyme from anthocyanin-containing cells separated into three peaks, and that from anthocyanin-free cells, into only two peaks. This difference is discussed in the context of the lack of activity with p-coumaric acid in anthocyanin-free cells.
TL;DR: Differences in the mode of action of light and GA(3) during germination indicate that different kinds of processes are involved in the biochemical control of germination.
Abstract: The seeds of lettuce (Lactuca sativa L. cv. Grand Rapids) germinate in darkness at 25 C when treated by gibberellic acid (GA3) for 1 hour following 2 hours of imbibition. The time of GA3 application influences the rate and the final percentage of seeds that germinate. In contrast, red light illumination given at different times affects only the rate and not the final germination percentage. The early process(es) of germination initiated by GA3 or light treatment can be arrested by subjecting the treated seeds to a nongerminative temperature of 35 C. The results suggest differences in the mode of action of light and GA3 during germination. They indicate that different kinds of processes are involved in the biochemical control of germination.
TL;DR: The strong retention of accumulated GA( 1) confirms the possibility of a continuing requirement for GA(1) during the sustained response to a GA (1) "pulse" but raises the question of accessibility of the stored hormone for growth promotion.
Abstract: Excised lettuce (Lactuca sativa L. cv. Arctic) hypocotyls retain the ability to elongate in response to exogenously supplied gibberellic acid and gibberellin A(1) (GA(1)). We have studied the relationship between metabolism of GA(1) and elongation in this tissue. In 24 hours at 28 C, hypocotyls treated with 3 mum GA(1) double in length while controls elongate less than 45%. After an exogenous hormone supply is removed, hypocotyls continue to grow faster than untreated controls, although as the hormone application time is decreased, the GA(1) concentration required to effect a given length change increases. [(3)H]GA(1) was used to determine rates of hormone uptake, efflux, and metabolism. In the presence of [(3)H]GA(1), hypocotyls accumulate and metabolize lable for at least 24 hours. When the exogenous label is removed, the amount of acidic GA in the hypocotyl declines rapidly to a constant level while ethyl acetate-insoluble metabolites increase rapidly to a constant level. Lable accumulation and metabolism at any time are proportional to the external GA(1) concentration below 50 mum GA(1). Chromatographic analysis of radioactive compounds present in tissue extracts suggests that unaltered GA(1) is the major component of the acidic ethyl acetate-soluble fraction, and gibberellin A(8) is a minor component. The ethyl acetate-insoluble fraction appears to contain an unidentified GA(1) metabolite with chromatographic properties similar to those of GA(1). The strong retention of accumulated GA(1) confirms the possibility of a continuing requirement for GA(1) during the sustained response to a GA(1) "pulse" but raises the question of accessibility of the stored hormone for growth promotion.
TL;DR: The results suggest that the main effect of abscisic acid is probably outside the chloroplast, i.e. on the formation or transport of δ-aminolevulinic acid.
Abstract: The influence of phytohormones on chlorophyll and carotenoid formation during the greening of irradiated dark grown wheat leaves (Triticum aestivum L. cv. Starke II Weibull) was studied. Leaves were floated on solutions of abscisic acid, gibberellic acid and kinetin for 24 h. The chlorophyll and carotenoid contents were determined during a subsequent period of 48 h of continuous irradiation. Leaves treated with abscisic acid showed a longer lag phase and a lower rate of accumulation of chlorophyll as compared to the control than did leaves treated with gibberellic acid and kinetin. The carotenoid content was low both in leaves treated with abscisic acid and in those treated with gibberellic acid. Treatment with abscisic acid lowered the protochlorophyllide regeneration after a saturating light flash while gibberellic acid as well as kinetin had no effect. The influence of ABA was partly dependent on an increase of the wounded part of the cut leaf segments. The accumulation of protochlorophyllide in leaves treated with δ-aminolevulinic acid was not affected by the different hormonal treatments. These results suggest that the main effect of abscisic acid is probably outside the chloroplast, i.e. on the formation or transport of δ-aminolevulinic acid.
TL;DR: The results appear to favour the view that tiller bud development is controlled by a competition for assimilates with the roots and main shoot.
Abstract: SUMMARY
The effects of foliar and root applied 6-benzylamino-9-(tetrahydropyran-2-yl)-9H-purine (PBA), 6-benzylamino-purine (BAP), indole-3-acetic acid (IAA) or gibberellic acid (GA3) on tiller bud growth were examined in cereal seedlings. Generally IAA and GA3 inhibited tiller bud growth whilst the synthetic cytokinins both markedly promoted growth. Some observations on stem and root growth were also recorded. The results are discussed with respect to the diversion of both assimilates and cytokinins and appear to favour the view that tiller bud development is controlled by a competition for assimilates with the roots and main shoot.
TL;DR: Gibberellic acid (GA3) stimulated the rooting of tomato leaf discs cultured on a defined nutrient medium in continuous darkness and significantly enhanced root initiation over the concentration range of 1 × 10−8 M to 1 ×10−4 M.
Abstract: SUMMARY
Gibberellic acid (GA3) stimulated the rooting of tomato leaf discs cultured on a defined nutrient medium in continuous darkness. In the presence of 2 × 10−4 M tryptamine, GA3 significantly enhanced root initiation over the concentration range of 1 × 10−8 M to 1 × 10−4 M. GA3 could be replaced by GA4/7 but not by kinetin. Indole-3-lactic acid was a highly active indole derivative in the induction of rooting in the tomato leaf discs. This effect was significantly enhanced by GA3. Possible reasons for this observation are discussed.
TL;DR: It is concluded that the chemical regulation of seed germination may be a consequence of the alteration of growth capabilities in either the axes or cotyledons, or both.
Abstract: Germination of nondormant but impotent small cocklebur seeds ( Xanthium pennsylvanicum Wallr.) was promoted profoundly with thiourea or benzyladenine, and slightly with gibberellic acid. Gibberellic acid was ineffective in causing the germination of dormant cocklebur seeds, although thiourea and benzyladenine were effective. Experiments with excised seed pieces showed that the promotive effects of thiourea, benzyladenine, and gibberellic acid on cocklebur seed germination were associated with the enhancement of growth of seed parts; thiourea stimulated predominantly the axial growth, whereas benzyladenine stimulated predominantly the cotyledonary growth. Potassium nitrate or indoleacetic acid had little effect on the initial growth of either axes or cotyledons. Except for gibberellic acid, all of the compounds employed enhanced ethylene production, but in general, the ethylene production seemed more likely to be a consequence of growth rather than a cause of it. We concluded that the chemical regulation of seed germination may be a consequence of the alteration of growth capabilities in either the axes or cotyledons, or both.
TL;DR: Investigation of polyphenol production in cut-injured sweet potato roots showed that polyphenols were produced in striking amounts in the proximal side of the tissue pieces, but only in small amounts in cells of the distal side, suggesting that IAA may play a role in the metabolic response to cut injury.
Abstract: Investigation of polyphenol production in cut-injured sweet potato (Ipomoea batatas Lam. cv. Kokei 14) roots by histochemical and quantitative methods showed that polyphenols were produced in striking amounts in the proximal side of the tissue pieces (2 cm thick), but only in small amounts in cells of the distal side. In response to cut injury, formation of the enzymes related to polyphenol biosynthesis, phenylalanine ammonia-lyase and trans-cinnamic acid 4-hydroxylase, was also pronounced in the proximal side of the tissue pieces and slight in the distal side. The similar polarity was observed in the development of activities of various enzymes, such as NADPH-cytochrome c oxidoreductase, acid invertase, peroxidase, o-diphenol oxidase, and cytochrome c-O2 oxidoreductase. Acropetal development of polyphenol contents and of various enzyme activities may be related to the acropetal movement of indoleacetic acid (IAA) in roots of various plants. Treatment of the distal surface of tissue pieces with IAA or 2,4-dichlorophenoxyacetic acid caused polyphenol production but treatment with gibberellic acid, abscisic acid, kinetin, or ethylene had little effect. The results suggest that IAA may play a role in the metabolic response to cut injury.
TL;DR: Metabolic alterations in germinating rice seeds as influenced by toxic concentrations of cupric sulphate were studied with respect to nucleic acids, proteins and hydrolytic enzymes, i.e. α-amylase, ribonuclease (RNase), adenosine triphosphatase, phytase and protease, resulting in reduced RNA/protein and DNA/protein ratios.
TL;DR: Application of GA(3) induced complicated changes in the germination of both species in relation to light quality and these phenomena are explainable by assuming two counteractive reactions (germination-promoting and germination-inhibiting) which are both activated by appliedGA(3).
Abstract: Effects of light and gibberellic acid (GA(3)) application on the germination of Dioscorea tokoro Makino and Dioscorea tenuipes Franch. et Savat. were observed. For complete germination, seeds of both species required prechilling in moist condition before incubation at a higher temperature. Red light irradiation during the incubation after the prechilling promoted germination; blue, green, or far red light markedly inhibited the germination of both species.Application of GA(3) induced complicated changes in the germination of both species in relation to light quality. In the germination of D. tokoro, GA(3) inhibited in the dark and red; however, it promoted germination in blue and far red light. GA(3) promoted germination of D. tenuipes in the dark and in blue, green, or far red light. These phenomena are explainable by assuming two counteractive reactions (germination-promoting and germination-inhibiting) which are both activated by applied GA(3).