Absence of Red Light-Induced Stimulation of Growth in the Hook of Etiolated Dwarf-Pea Seedlings

Red light inhibited the growth of the apical part of the hookin dark-grown seedlings of a dwarf variety (cv. Progress No.9) of pea (Pisum sativum L.), whereas it promoted such growthin a tall variety (cv. Alaska). In the elongation zone of theepicotyl of the dwarf variety the extent of inhibition of growthwas similar to or even smaller than that in the tall variety.Local irradiation of the apical part of the hook also causedinhibition of growth in the hook of the dwarf variety and promotionof growth in the tall variety. The inhibition of growth in theapical part of the hook of cv. Progress may be involved in thedwarfism induced by irradiation with red light of this cultivar. (Received May 15, 1989; Accepted April 27, 1990)     

Auxin-gibberellin interaction in apical dominance: Experiments with tall and dwarf varieties of pea and bean

Summary Seedlings of dwarf and tall varieties of pea and bean, growing in John Innes Compost No. 2, were studied in relation to the effects of decapitation, indole-3-acetic acid (IAA), and gibberellic acid (GA₃) on axillary bud growth. In all varieties, GA₃ antagonized the inhibitory influence of IAA on bud growth when both hormones were applied to the upper cut end of the stem. Thus, GA₃ caused a reduction in IAA-induced correlative bud inhibition in tall, as well as in dwarf, plants. These results agree with those obtained by several workers, but contrast with some recent reports of increased apical dominance in a tall pea variety when seedlings were treated with GA₃ in addition to IAA. An attempt was made to identify the cause of opposite results being obtained by different workers, and it is considered that possibly the most important factor is mineral nutrition.     

Effects of Gibberellin on the Arrangement and the Cold Stability of Cortical Microtubules in Epidermal Cells of Pea Internodes

Longitudinal microtubules are predominant in epidermal cellsof the 3rd internodes of dwarf pea (Pisum sativum L. cv. LittleMarvel) seedlings. In more than 50% of the cells, cortical microtubulesare running parallel to the cell axis. GA₃ promotes elongation of the internodes and gives rise toa predominance of transverse microtubules. In more than 60%of the GA₃-treatd cells, cortical microtubules are running transverseto the cell axis. Longitudinal microtubules in the GA₃-untreated cells are resistantto low-temperature treatment, but transverse microtubules inthe GA₃-treated cells are sensitive to it. Longitudinal microtubulesare present in GA₃-treated epidermal cells with low frequency.They are resistant to low-temperature treatment. Longitudinal, oblique and transverse microtubules are presentwith almost the same frequency in epidermal cells of the 3rdinternodes of tall pea (cv. Early Alaska) seedlings. GA₃ promoteselongation of the internodes also in tall pea seedlings, butit does not alter the direction of cortical microtubules sodistinctly as it does in dwarf pea seedlings. As in dwarf pea seedlings, longitudinal microtubules are resistantto low-temperature treatment, and transverse microtubules aresensitive to it in tall pea seedlings. (Received September 19, 1986; Accepted December 26, 1986)     

Natural Inhibitors in Normal and Dwarf Peas

Extracts of light- and dark-grown, normal and dwarf pea seedlings(Pisum sativum L. cv. Alaska and Radio respectively) were purifiedby solvent partitioning, column, paper and thin layer chromatography.Conventional acid-base partitioning was modified because thelarge volumes of material processed caused considerable crosscontamination between neutral and acidic phases. At each stepof the purification, fractions were tested for inhibitory activitywith the wheat coleoptile and pea section tests. Recovery ofabscisic acid was monitored using ¹⁴C-abscisic acid. Estimatesof abscisic acid content were marie using gas-liquid chromatographyand the wheat coleoptile bioassay. Two main inhibitors were found; one of these was identifiedas (+)-abscisic acid, the other (inhibitor Y) has not been identifiedbut displays chromatographic properties which suggest that itis neutral in nature. Abscisic acid was found in both rootsand shoots of light- and dark-grown pea seedlings. InhibitorY was found in trace amounts in the roots of dark-grown plantsbut could not be detected in the shoots. Growth in light induceda manifold increase in inhibitor Y concentration compared withdark-grown plants. The level of Y was threefold greater in light-growndwarf shoots than in comparable light-grown tall shoots. Therewas, thus, a correlation between the concentration of inhibitorY and the light-induced inhibition of stem elongation.     

Gibberellins in the embryonic axes of tall and dwarf beans and their changes with initial growth

Ten gibberellin-like activities were detected in the dry embryonicaxes of tall (cv. Kentucky Wonder) and dwarf (cv. Masterpiece)beans (Phaseolus vulgaris L.) using the lettuce hypocotyl assayof thin-layer chromatograms; 2 in the non-acidic ethyl acetatefraction (NEI, NEII), 3 in the acidic ethyl acetate fraction(AEI, AEII, AEIII), 2 in the non-acidic n-butanol fraction (NBI,NBII) and 3 in the acidic n-butanol fraction (ABI, ABII, ABIII).There was no qualitative difference in these gibberellins betweenthe tall and dwarf axes, but all, particularly AEIII, NBII andABIII as the main gibberellins in the axes, were contained muchmore abundantly in the tall axes. In both axes the gibberellinactivities of most fractions decreased during germination.Theamounts of some gibberellins in tall axes without cotyledonswere greater than those in axes with cotyledons at 48–72hr of germination. Neither AMO-1618 nor CCC caused significantreduction in the levels of the gibberellins. Axis growth inthe early germinating period depended on the gibberellins storedin the axis, itself. (Received November 26, 1974; )     

Peroxidase Isoenzymes in Development of Tall and Dwarf Cultivars of Rice

Four cultivars of rice, Hansraj (tall), Jamuna, Padma and Sabarmati(all dwarf) were analysed for variation in isoperoxidase patternsduring development by horizontal starch-gell electrophoresis.The samples were taken at weekly intervals, starting with soakedseeds (12 h) until the post panicle stage. There is a distinctpattern of peroxidase isoenzymes in the tall and dwarf cultivarsstudied. Some isoenzymes appear at a particular developmentalstage while others disappear while some remain fairly constantonce they are activated. Hansraj showed more qualitative fluctuationsin peroxidase than did the three dwarf varieties. A few isoperoxidaseswere specific to some varieties such as bands A₃ and A₇ forHansraj and band A₄ for Sabarmati. These specific bands of peroxidasemay have some role to play in development of Hansraj (tall)and Sabarmati (with aroma). Besides this, greater fluctuationsin peroxidase activity in the tall variety may be due to loosecontrol in the regulation of peroxidase activity. The significanceof controlling elements of enzyme activity is discussed.     

The Distribution of Substances similar to Gibberellic Acid in Higher Plants

Gibberellic-acid-like substances have been found in extractsfrom all parts of seedlings of tall and dwarf peas and in matureseeds of wheat, French bean and tall and dwarf peas. They werepresent in amounts equivalent to o‘1–0’3 µg-gibberellicacid in 100 plants (F.W. 100–200 g.). Immature runnerbean seed yielded larger quantities, equivalent to 0.25 µg.gibberellic acid per gram fresh weight, distributed betweentestas, cotyledons, and embryos.     

Leucine Aminopeptidase Activity in Tall and Dwarf Cultivars of Rice at Successive Stages of Development

Studies to determine the variations in leucine aminopeptidase(LAP) activity in tall and dwarf cultivars of rice were conductedby horizontal starch gel electrophoresis. The samples were takenat weekly intervals starting with soaked seeds (12 h) untilthe post-panicle stage. There is a distinct pattern of LAP isoenzymesin tall and dwarf cultivars studied. Some isoenzymes appearat a particular developmental stage and others disappear whilesome remain fairly constant once they are formed. A tall cultivar(Hansraj) shows greater fluctuations during the course of developmentthan the dwarf cultivars. These studies throw light on the transitorynature of these enzymes and show apparently differential geneaction.     

Comparison of endogenous gibberellins and response to applied gibberellin of some dwarf and tall wheat cultivars

Summary A number of dwarf wheat cultivars of the Norin 10 type were compared with several tall forms. Applied gibberellic acid markedly stimulated the growth of seedlings of the tall cultivars but not the growth of dwarf seedlings. Several other gibberellins were also inactive when tested with one dwarf cultivar. De-embryonated grains of all cultivars formed -amylase in response to gibberellic acid. Gibberellic acid caused an increase in soluble carbohydrates in the leaves of the tall cultivars but not in those of the dwarfs.Germinating grains, light-grown seedlings and developing stems of the dwarf cultivars contained more endogenous gibberellin-like activity than those of tall cultivars. It is suggested that the dwarf cultivars have a block to the utilisation of gibberellin in the shoot.     

Comparison between the preservation of chloroplast structure in the dark and the turnover rate of chlorophyll-protein complexes in a moss and two varieties of pea

The senescence and preservation of the structure of the chloroplastin the dark was studied in the protonema of Ceratodon purpureusand in two varieties of pea, a tall variety "Dippe Maj" anda dwarf variety "Early low". The latter variety is better ableto survive in darkness, probably because of the larger amountof starch in its chloroplasts. The integrity of the chloroplastswas better preserved in the moss than in the peas. During isolationof the chlorophyll-protein complexes, there was no decreasein the specific activity of the total lamellar extract in anyof the dark-grown materials. This contrasts with the turnoverof chlorophyll-protein complex (CP) II in the dark-grown moss.In the light, CP II had a half life of two weeks in both themoss and the higher plants, whereas no turnover was evidentin CP I. The lack of turnover for CP I is connected with itsdecrease in senescence. ¹Present address: Department of Botany, University of Turku,20500 Turku 50, Finland. (Received July 13, 1979; )     

Solvent and Chemical Impurities as Sources of Gibberellin-like Growth-Promoting Activity

Experiments are described in which a standard procedure usedfor the extraction of endogenous gibberellin-like substancesfrom plants was carried out in the absence of plant materialto give ‘blank’ extracts. Acidic, basic, and neutralfractions of blank extracts all showed variable gibberellin-likeactivity on d-5 dwarf maize and lettuce hypocotyls, though oftenat a low level. Acidic fractions showed activity on d-2 dwarfmaize, but none of the fractions was active on dwarf peas oron tomato seedlings. One sample of sodium bicarbonate appearedto be contaminated by two gibberellin-like substances. Someactivity was observed in ethanol, chromatography paper, andammonium acetate, but none in methanol or redistilled ethylacetate. There were wide variations between the results of comparableexperiments. In the light of these results possible precautionsfor experiments involving extraction of endogenous gibberellin-likesubstances are discussed.     

The Promotion of Indole-3-acetic Acid Oxidation in Pea Buds by Gibberellic Acid and Treatment

Terminal buds of dark-grown pea (Pisum sativum) seedlings have an indole-3-acetic acid oxidase which does not require Mn(2+) and 2,4-dichlorophenol as cofactors. Oxidase activity is at least 50 times higher in buds of tall peas than in dwarf seedlings. Administration of gibberellic acid to dwarf peas stimulates both growth and indoleacetic acid oxidase activity to the same levels as in tall seedlings. By contrast, indoleacetic acid oxidation assayed in the presence of Mn(2+) and 2,4-dichlorophenol proceeds at similar rates regardless of gibberellin application. Treatment of tall peas with the growth retardant AMO-1618 reduces growth and oxidase activity. Such treated seedlings are indistinguishably dwarf. The enzyme does not appear to be polyphenol oxidase, nor do the results suggest that reduced activity in dwarf buds is due to higher levels of a dialyzable inhibitor. The peroxidative nature of the oxidase is probable.     

Effect of Seed Treatment on Growth and Growth-substance Content of Dwarf French Beans (Phaseolus vulgaris)

The longer the seeds of dwarf French bean (Phaseolus vulgaris)were soaked in water before sowing, the smaller were the seedlingsthey produced. Soaking for 24 hours removed only little drymatter, but detectable amounts of a gibberellin and a betaine.The amounts of these two removed increased with increased timeof soaking. Long soaking of seeds decreased the amounts of gibberelinand auxin in the cotyledons, and of gibberellin, auxin, andbetaine in the primary leaves of seedlings. Aerating, cooling,or increasing the volume of water in which the seeds were soakedalso retarded the growth of the seedlings, but did not affectthe amount of growth substance removed from the seeds or containedin the cotyledons. The deleterious effect of soaking seeds wasnot alleviated by treating the seeds or seedlings with gibberellicacid or glycine betaine. Although larger seedlings were producedby heavy than by light seeds, their cotyledons and primary leavescontained similar concentrations of growth substances.     

Role of Assimilates and Phosphates in the Control of Internode Elongation in Tall and Dwarf Indica Rice Varieties

Six indica rice varieties belonging to three duration groups,each group containing one tall and one dwarf variety, were grownunder irrigated field conditions during the wet season of 1986.At the time of culm elongation, the distal 5–6 internodesof a variety elongated. The pattern of extension was hierarchical,each successive internode dominating the one immediately belowit and hence the final internode lengths increased in acropetalfashion from the bottom to the top. Between the tall and dwarfvarieties, the lengths of the individual intemodes did not differmuch in the apical and basal positions, but significant differenceswere found between the lengths of the middle internodes. Withincrease in length, the internodes became visibly thinner anddry matter content per unit length decreased. Analyses of solublecarbohydrates, amino acids, and phosphate contents of the internodesindicated that the concentration of the metabolites increasedin acropetal succession from the base to the apex. In general,the dwarf varieties contained at least the same, if not a higherconcentration of the metabolites as the tall varieties. Thepossible role of the metabolites in internode extension is discussed. Key words: Rice, internode extension, assimilates, phosphates, sink     

The effect of cotyledons on hypocotyl elongation in light-grown bean seedlings: Comparison between dwarf and tall varieties

Hypocotyl sections with and without the cotyledons were cutfrom bean seedlings and incubated under white light of 6000lux. The cotyledons had an inhibitory effect as well as a promotiveeffect on hypocotyl growth. The former effect was more strikingin the dwarf variety, and the latter in the tall variety. Whenthe hypocotyl units were exposed to light for shorter times(6 hr or less) or incubated under weaker light (1600 and 50lux), the inhibitory effect of the cotyledons decreased greatly,and in the tall variety the presence of cotyledons producedno inhibition, but a promotion of hypocotyl growth. GA treatmentenhanced hypocotyl growth and counteracted the growth inhibitioncaused by the cotyledons. On the whole, the GA effect was moremarked in the tall variety than in the dwarf. The elongation of bean hypocotyls may be controlled by a balancebetween the inhibitory and promotive effects of cotyledons,and the predominance of the former over the latter may be oneof the causes for expressing dwarfing. (Received November 13, 1976; )     

Translocation of Photosynthates in Tall and Dwarf Varieties of Pea, Pisum sativum

Quantitative studies of the translocation of radiocarbon from a young expanded leaf of two tall varieties (Improved Pilot and Thomas Laxton) and two dwarf varieties (Little Marvel and Meteor) of Pisum sativum showed that 40 to 45 per cent of the radiocarbon was exported from the ¹⁴CO₂ treated leaf after 24 hours in all four varieties. Although substantial export to the upper shoot always occurred it was more marked in the two tall varieties. Pre-treatment with GA did not affect total fixation but increased total export from the ¹⁴CO₂ treated leaf in cv. Meteor and decreased it in cv. Improved Pilot. GA had no effect on the translocation pattern in the tall plants but modified that of the dwarf plants to correspond to that found in the tall varieties.     

Effects of chloromequat chloride on related tall and dwarf rice varieties

The effects in growth room experiments of three levels of 2-chloroethyltrimethylammonium chloride (chloromequat chloride; CCC) at two nitrogen levels were studied on a tall rice variety and a mutant dwarf derivative. CCC was found to reduce plant height in both varieties, to increase tiller number and spikelet number on the main panicle or in total but to delay flowering. Chemical dwarfing cannot be regarded as an alternative to genetic dwarfing since mutants may be shorter than chemically treated tall genotypes and may themselves respond favourably to further treatment.     

Natural growth inhibitors associated with the cotyledon effect in light-grown dwarf and tall beans

The contents of non-acidic, acidic and bound growth inhibitorsin hypocotyls and cotyledons were compared between dark- andlight-grown dwarf and tall beans by means of thin-layer chromatographyand bioassay. In the non-acidic fraction, one major inhibitoryactivity appeared on the chromatogram, but its Rf zone was differentbetween hypocotyls and cotyledons. In both the acidic and boundinhibitor fractions, one major inhibitory activity appearedat the Rf zone corresponding to ABA. The ABAIike substance whichwas the major inhibitor in the hypocotyl was more abundant inlight-gorwn than dark-grown ones, especially in the dwarf variety,but light irradiation did not cause its transport from cotyledonsto the hypocotyl. A larger amount of bound ABA-like substance,which was the major inhibitor in the cotyledon, was presentin the dwarf than the tall variety regardless of the light condition.Cotyldon-enhanced photoinhibition of hypocotyl growth couldnot be explained by the levels of the xanthoxinand ABA-likeinhibitors, or the transport of these free inhibitors from cotyledons. (Received September 8, 1977; )     

ent-Kaurene Biosynthesis in Cell-Free Extracts of Excised Parts of Tall and Dwarf Pea Seedlings

Investigations on the sites of ent-kaur-16-ene (ent-kaurene) biosynthesis were conducted with cell-free extracts from several excised parts of 10-, 13-, and 16-d-old tall and dwarf pea (Pisum sativum L.) seedlings. [¹⁴C]Mevalonic acid was incorporated into ent-kaurene in cell-free extracts from young developing leaves and elongating internodes of tall (`Alaska') and dwarf (`Progress No.9') pea seedlings at all three stages of development. ent-Kaurene biosynthesis also occurred readily in cell-free extracts from shoot tips, petioles, and stipules near the young elongating internodes. The ent-kaurene-synthesizing activity found in young developing tissues declined as tissues matured. Little or no activity was detectable in enzyme extracts from cotyledons and root tips at different stages. In light grown tall pea internodes ent-kaurene-synthesizing activity was low as they began to elongate, reached a maximum when the internodes reached about 2 cm in length and declined as they matured. Activity in extracts of dwarf shoot tips and internodes was generally lower than in equivalent tall plants, but the activity in dwarf leaves and stipules was somewhat higher than in tall plants. With the exception of root tips, there is a strong correlation between growth potential of a tissue and the rate of ent-kaurene biosynthesis in extracts from that tissue.     

3个向日葵品种生长期内水分、蛋白质和总黄酮含量动态变化

本实验研究了3个向日葵品种在生长周期内茎、叶及茎叶混合样的水分、蛋白质和总黄酮含量的动态变化.结果表明:向日葵不同品种、不同生长期以及同一品种的不同部位的水分、蛋白质、总黄酮含量均存在差异.水分含量整体呈现下降趋势,且茎＞茎叶混合＞叶;蛋白质含量为叶＞茎叶混合样＞茎,其中高秆食用葵叶片中蛋白质含量为8.10g/100g...