Cell-Free Synthesis of Rice Prolamin

Polyadenylated RNA was isolated from the protein-body rich fractionof developing rice (Oryza sativa. L) seeds. In a wheat germcell-free system, the isolated polyadenylated RNA produced polypeptideswith the same solubility as prolamin subunits. The electrophoreticmobility of the polypeptides suggested the presence of a signalpeptide. ⁴To whom correspondences should be addressed (Received May 13, 1986; Accepted July 25, 1986)     

Identification of 4-Chloroindole-3-acetic Acid and Its Methyl Ester in Immature Seeds of Vicia amurensis (the Tribe Vicieae), and Their Absence from Three Species of Phaseoleae

The natural chlorinated auxins 4-chloroindole-3-acetic acid(4-Cl-IAA) and its methyl ester (4-Cl-IAA Me ester) were found,in addition to IAA and its Me ester, by gas chromatography-massspectrometry in immature seeds of Vicia amurensis, a Vicieaespecies. In contrast, only non-chlorinated, IAA and IAA Me esterwere present in immature seeds of three Phaseoleae species.These results are further evidence of the wide distributionof 4-Cl-IAA and its Me ester in various Vicieae. (Received October 3, 1986; Accepted December 22, 1986)     

Protein Synthesis During Rehydration, Germination and Seedling Growth of Naturally and Precociously Matured Soybean Seeds (Glycine max)

p. 86, line 6, should read: These patterns of soluble protein synthese are similar to thoseobserved after precocious maturation and subsequent rehydrationof castor bean (Kermode and Bewley, 1985a, b, 1986), and withinaxes of Phaseolus vulgaris L. seeds (Dasgupta and Bewley, 1982). instead of: These pattern of protein synthesis. Unlike castor bean thoseobserved after precocious maturation and subsequent rehydrationof castor bean (Kermode and Bewley, 1985a, b, 1986), and withinaxes of Phaseolus vulgaris L. seeds (Dasgupta and Bewley, 1982).     

Changes in RNA and Protein Metabolism Associated with Alterations in the Germination Efficiency of Sunflower Seeds

Precise knowledge of seed quality after harvest and during storageis of particular importance for seed producers. We analyseddifferent sunflower seed lots (Helianthus annuusL.) characterizedby extremes of germination ability. We used RNA analysis tostudy possible changes in gene expression in seeds unable togerminate. Total RNA content was very small in dry seeds showinga low germination ability. Capacity for total RNA synthesisat the onset of imbibition was also reduced in these seeds.In addition, correlations were found between these parametersand germination ability at 19 °C. We demonstrated a highcorrelation between the amount of total RNA in the dry seed,the capacity of RNA synthesis at the onset of imbibition andthe seed moisture content at the time of the harvest. The abilityof dry seed mRNAs to be translatedin vitrowas also reduced andseven polypeptides, from stored mRNAs, were characteristic ofthe cotyledons from high germinability seeds. Germination canthus be affected at several levels including membrane, enzymaticand nucleic acid deteriorations. Gene expression; germination ability; Helianthus annuusL.; marker; protein; RNA; seed; sunflower     

Desiccation of Phaseolus vulgaris Seeds During and Following Germination, and its Effect Upon the Translatable mRNA Population of the Seed Axes

Misra, S. and Bewley, J. D. 1986. Desiccation of Phaseolus vulgansseeds during and following germination, and its effect uponthe translatable mRNA population of the seed axes.—J.exp. BoL 37: 364–374. After imbibition and germination, seeds of P. vulgaris passfrom a stage where they are insensitive to desiccation to astage where they are sensitive. Desiccation of seeds duringthe sensitive stage results in an almost total impairment ofprotein synthesis upon subsequent rehydration. Seeds desiccatedduring the desiccation-tolerant stage, however, resume proteinsynthesis at almost control levels. The protein patterns obtained following in Vitro translationof bulk RNA from fresh imbibed, desiccated, and desiccated-rehydratedseed axes were qualitatively similar at 5 HAI (the desiccation-tolerant stage). The drying treatment resulted in increasedintensity of extant proteins at 5 and 12 HAI. At 12 HAI (thetransition stage between the desiccation-tolerant and desiccation-intolerantphases) desiccation and subsequent rehydration triggered synthesisof a unique set of proteins-the rehydration proteins. At 20HAI (the desiccation-intolerant stage) desiccation resultedin an overall decline in the intensity of proteins synthesizedin vitro. Also the rehydration proteins were not synthesizedin response to a drying and rehydration treatment at this time. Key words: Seed germination, desiccation, mRNA, in vitro translation, Phaseolus vulgaris     

Changes in Lipoxygenase Components of Rice Seedlings during Germination

Changes in lipoxygenase (LOX) activity were followed duringthe germination of rice seeds. The enzyme activity of 3-day-oldseedlings was 20 times higher than that of ungerminated seeds.Sixty per cent of the increased activity was found in shoots.The increase in LOX activity was mainly due to an increase inlipoxygenase-2 (LOX-2), a minor component in ungerminated seeds;this increase was inhibited by cycloheximide. LOX-2 was isolatedfrom the 3-day-old seedlings and compared for its enzymologicalproperties with rice lipoxygenase-3 (LOX-3), a major componentin ungerminated seeds. Both LOX-2 and LOX-3 were stable at pH5 to 8, but LOX-2 was more heatstable than LOX-3. Apparent K_mvalues of LOX-2 and LOX-3 for linoleic acid were 170 and 59µM, and those for linolenic acid were 5,300 and 88 µM,respectively. Both LOXs were inhibited by some metal ions andantioxidants. (Received February 5, 1986; Accepted May 9, 1986)     

Kinetics of Phenylalanine Ammonia-Lyase and the Effect of L-{alpha}-aminooxy-{beta}-phenylpropionic Acid on Enzyme Activity and Radicle Growth in Germinating Lettuce Seeds

The effects of different concentrations of L--aminooxy-ß-phenyIpropionicacid (AOPP), an analog of L-phenylalanine, on the activity ofphenylalanine ammonia-lyase (PAL, EC 4.3.1.5 [EC] ) and the growthof radicles in 24 h old germinating lettuce (Lactuca salivaL.) seeds were investigated. AOPP causes a significant inhibitionof PAL activity in the seeds (85% inhibition at 10⁴ M). It alsocauses a stimulation of radicle growth at that concentration.The results show that the inhibition of PAL by AOPP may be dueto an irreversible binding of the inhibitor to the enzyme leadingto its inactivation. AOPP also inhibits ethylene biosynthesisin germinating lettuce seeds which could probably explain thestimulation of radicle growth in these seeds. The enzyme shows typical Michaelis-Menten kinetics. The K_m forL-phenylalanine is 4.2 x 10⁵ M. The enzyme does not show anytyrosine ammonia-lyase activity. Various substrate analogs suchas D-phenylalanine, p-fluorophenylalanine, ß-phenyllacticacid, tryptophan and the product of the enzyme reaction, trans-cinnamicacid, inhibit the enzyme competitively. A number of intermediatesand endproducts of the phenylpropanpid pathway, except chlorogenicacid, do not show any inhibition. ¹Scientific contribution number 1423 from the New HampshireAgricultural Experiment Station. (Received May 9, 1986; Accepted September 8, 1986)     

RNA Metabolism During Breakage of Seed Dormancy by Low Temperature Treatment of Fruits of Acer plataanoides(Norway Maple)

Stratification of Acer platanoides fruits at 4 °C led toan accumulation of RNA in the embryo axis and to breakage ofseed dormancy. The accumulated RNA was mainly rRNA. Storageof fruits at 17 °C led neither to an accumulation of RNAnor to breakage of dormancy. The proportion of embryo axis mRNA,as measured by poly(A) content, decreased during both fruitstorage and stratification, although levels of poly(A) wereconsistently lower in embryo axes from stored seeds. Isolatedembryos from both stored and stratified fruits were capableof incorporating [³H]uridine into embryo axis RNA. When assayedat 17–20 °C, however, this incorporation was significantlylower in embryos of stored fruits. The distribution of radioactivitybetween the different RNA species was similar in both storedand statified seeds. Acer platanoides, Norway Maple, dormancy, fruit, seed, ribonucleic acid, stratification, nucleic acid metabolism     

Synthesis of Canavalin and Concanavalin A in Maturing Canavalia gladiata Seeds

In successive stages of seed development of Canavalia gladiata,seeds were harvested, and time-course changes of the accumulationof canavalin and concanavalin A (Con A) were investigated bySDS-gel electrophoresis and protein blot analysis. Results showedthat the synthesis of both seed proteins started as early as30 days after flowering (DAF) and that they had different accumulationpatterns during seed development. The synthesis and accumulationof canavalin were most active at SOSO DAF, whereas the contentof Con A continued to increase gradually until the seed maturationwas nearly completed (80 DAF). Next, an RNA fraction was preparedfrom seeds of 40 DAF, translated in a wheat germ system andits translation products analyzed by the immunoprecipitationand SDS-gel electrophoresis. The mol wt (about 48,000) of thein vitro product immunoprecipitated with the antiserum to canavalinwas very closed to that of canavalin. The mol wt (34,000) ofthe in vitro product immunoprecipitated with the antiserum toCon A was about 4,000 higher than that of Con A. Canavalin-mRNAwas present as early as at 30 DAF and its translational activitywas the highest at 35–40 DAF. Con A-mRNA was also detectedat 30 DAF and, in contrast to canavalin-mRNA, high activitieswere maintained until 75 DAF. (Received November 25, 1986; Accepted January 29, 1987)     

Isolation of cDNA for Pea Phytochrome Using an Expression Vector

Partially purified phytochrome mRNA was obtained from etiolatedpea epicotyls by polyribosome immunoprecipitation or by sizefractionation of total poly(A)⁺RNA, and used for the synthesisof double-stranded complementary DNA (cDNA). cDNA librarieswere constructed using an Escherichia coli expression vector,pUC9, and screened for phytochrome cDNA by colony immunologicalassay. Nine colonies were found to produce a 27 kDa polypeptidethat was reactive to both polyclonal and monoclonal antipeaphytochrome antibodies. The plasmids from these colonies containedcDNA inserts of 1.2 or 2.0 kbp. Hybridization-arrest translationassay verified that the cDNA clones contained a sequence codingfor phytochrome polypeptide. RNA blot hybridization analysisindicated that the cDNA hybridized to a 4.1 kb poly(A)⁺RNA indark-grown pea. (Received March 22, 1986; Accepted June 13, 1986)     

Changes in Nucleic Acid Levels Associated with Improved Germination Performance of Tomato Seeds After Low Temperature Presowing Treatment

Low temperature presowing treatment (LTPST) of tomato seeds,var. Moneymaker, increases their rate of germination. Duringthis treatment there is a large increase in nucleic acid content,especially rRNA, within the seeds. Denaturing gel electrophoresisindicates that the quality of this RNA improves during LTPST.Although replacement of fragmented rRNA may be an importantprerequisite for successful germination, the data show thatthis is unlikely to be the immediate cause of more rapid seedgermination. When compared with untreated controls during subsequentgermination, treated seeds show reduced rates of nucleic acidaccumulation and reduced RNA polymerase activity per unit DNA,implying that rRNA synthesis within these seeds is under somemeasure of stringent control. The association between nucleicacid metabolism and germination is discussed. tomato, Lycopersicon esculentum Mill., seed germination, presowing treatment, RNA, RNA polymerase     

Preformed mRNA and Light-induced Germination of Pine (Pinus thunbergii) Seed

The mRNAs were isolated from dry, dark-imbibed and light-imbibedpine (Pinus thunbergii) seeds, in which germination is inducedupon exposure to light, and their translational activities ina wheat embryo cell-free system were examined. A portion ofthe mRNA extracted from each type of seed appeared to be poly(A)⁺RNA.A significant translational activity was already present inthe RNA fraction isolated from the dry pine seeds. The preformedmRNA seems not to be translated in vivo during the dark-imbibition,since most of the in vivo protein synthesis did not occur untilthe seeds were exposed to light. The SDS polyacrylamide gelelectrophoregrams of the polypeptides synthesized in vitro inresponse to either the preformed mRNA or the mRNAs from thedark-imbibed or light-imbibed seeds were qualitatively identical;thus it seems that the preformed mRNA is conserved during darkimbibition, and that its translation is initiated after theexposure of the imbibed seeds to light. (Received August 10, 1981; Accepted May 15, 1982)     

The Synthesis of Ethylene in Melon Fruit during the Early Stage of Ripening

The levels of mRNA and polypeptide for a 1-aminocyclopropane-1-carboxylate(ACC) oxidase were studied to identify the tissues in whichthe synthesis of ethylene first occurs during the initial stageof ripening. RNA and immunoblot analysis showed that the levelsof the mRNA and polypeptide for ACC oxidase were very low inunripe fruit. They first became detectable in the placentaltissue at the pre-climacteric stage, and then their levels increasedin the mesocarp tissue during the climacteric increase in theproduction of ethylene. Two mRNAs for ACC synthase (transcribedfrom ME-ACS1 and ME-ACS2) were detected in the placental tissueand seeds at the pre-climacteric stage, but only the level ofME-ACS1 mRNA, which has been characterized as the mRNA for awound-inducible ACC synthase, increased in mesocarp, placentaltissues and seeds during ripening. The level of ME-ACS2 mRNAthat was isolated from etiolated seedlings of melon, did notchange markedly during ripening. These results suggest thatthe central region of melon fruit (placental tissue and seeds)plays a major role in the production of ethylene during theearly stage of ripening. ³These three authors made equal contribution to this study.     

Stored mRNA in Pine Seeds: Prolonged Preservation in Dry Seeds and Disappearance during Germination

RNA blot hybridization was performed with cDNA clones of storedmRNA in dry seed of Pinus thunbergii. The stored mRNA specieswere preserved in the dry seeds for at least 14 years. One ofthe mRNAs disappeared rapidly during germination, while otherswere detected until a late stage of germination. (Received August 19, 1991; Accepted February 26, 1992)     

Inhibition, of hormone-induced ethylene synthesis by the indole plant-growth inhibitor from Abrus precatorius seeds

The plant growth inhibitory fraction from Abrus precatoriusseeds inhibited protein and RNA synthesis and IAA- and kinetin-stimulatedethylene production by lettuce seedlings as well as IAA-stimulatedgrowth and ethylene production by wheat coleoptile sections. (Received August 28, 1974; )     

Moisture Loss as a Prerequisite for Seedling Growth in Soybean Seeds (Glycine max L. Merr.)

Rosenberg, L. A. and Rinne, R. W. 1986. Moisture loss as a prerequisitefor seedling growth in soybeanseeds (Glycine max L. Merr.).—J.exp. Bot. 37: 1663–1674. As soybean seeds [Glycine max (L.) Merr.] develop, they undergoa change in seed moisture. When excised prematurely from thepod and planted, seeds do not exhibit seedling growth until63 d after flowering (DAF) when the seed moisture has fallenbelow 60%. In contrast, seed germination (radicle protrusion)can occur when seeds as young as 35 DAF (68–79% moisture)are excised, but this germination docs not lead to comparableseedling growth frequencies unless seeds are first given a moistureloss treatment to artificially reduce their moisture below 60%.A moisture loss treatment applied at 35 DAF thus enables seedto undergo the transition from germination (cell expansion)to seedling growth (cell division and expansion) to the extentthat treated immature seed have a vigour index comparable toseeds matured on the plant (100%). The pattern of protein synthesisin vivo was examined in 35 DAF seed using [³⁵S]-methionine incorporation.When moisture loss treatment was applied for 24 h to 35 DAFseeds, seeds synthesized several new polypeptides when comparedwith untreated seeds at the same developmental stage. The sameseed samples showed 0% seedling growth in the absence of moistureloss treatment and 80% seedling growth when the treatment hadbeen applied. Moisture loss from soybean seeds appears to bea prerequisite for the synthesis of new proteins which may bepart of the metabolic process or processes that allow the soybeanseed to undergo the transition from seed germination to seedlinggrowth. Key words: Moisture loss, germination/growth, soybean     

Natural Ageing: Poly(A) Polymerase in Germinating Embryos of Triticum durum Wheat

The viability of seeds is associated with ageing and storageconditions. A loss of viability is accompanied by slow germination,reduced growth, and a decline in protein and poly(A)⁺RNA synthesis.This paper reports on the activity of poly(A) polymerase indry and germinating embryos of Triticum durum Desf. cv. Cappellicaryopses of different ages and viability. The enzyme was presentas a single form during ageing and germination. The poly(A)polymerase was active at decreasing levels in all aged dry embryos,in parallel with loss of viability. Its activity strongly increasedduring the germination only in viable embryos. The observedincrease was due to de novo synthesis of the enzyme. Poly(A)polymerase synthesis was low during germination of less viableembryos and absent in older ones. Reduced poly(A) polymeraseactivity in dry or germinated wheat embryos may cause a shorteningof poly(A) chains in vitro and a decline in poly(A)⁺RNA synthesis.Copyright1995, 1999 Academic Press Triticum durum Desf. cv. Cappelli, wheat, embryo, natural ageing, poly(A) polymerase     

Environmental Factors Influencing the Expression of Dormancy Patterns in Weed Seeds

Buried seeds often show seasonal periodicity of dormancy. Dormancypatterns of Chenopodium album, Polygonum persicaria, Sisymbriumofficinale and Spergula arvensis were studied by burying seedsunder field conditions in sandy loam in December, 1986. Seedswere exhumed at regular intervals and germination was subsequentlytested in the laboratory. It was shown that the conditions ofthe germination test influenced the expression of the dormancypattern. Germination of C. album and 5. arvensis always dependedon the presence of light, whereas seeds of S. officinale completelylost their light dependency during the first winter. Applicationof nitrate during the germination test in light improved germinationof all species. Dark germination was not stimulated by nitratealone. Desiccation of the exhumed seeds at a r.h. of approx.15% enhanced germination under all conditions. A combinationof several stimulating factors revealed breaking of dormancymuch earlier in the season. During induction of secondary dormancythe effect of the test conditions was even more pronounced.Dormancy induction could be overlooked for several months whenseeds were desiccated and/or given nitrate during the germinationtest in light. It is hypothesized that in the field both desiccation- due to cultivation and dry spells - and nitrate enrichmentof the soil will influence the expression of the seasonal patternof dormancy and therefore enlarge the period of possible seedlingemergence Desiccation, dormancy pattern, germination, light, nitrate, seeds, weeds, Chenopodium album, Polygonum persicaria, Sisymbrium officinale, Spergula arvensis     

Effect of Thiolactomycin on Fatty Acid Synthesis in Higher Plants

Thiolactomycin (TLM), an antibiotic from Nocardia sp. No. 2-200,inhibited fatty acid synthesis in Avena leaves, with the concentrationcausing 50% inhibition being 0.38µg/ml. This antibioticis more inhibitory to the elongation of palmitic to oleic acidthan to the de novo synthesis of palmitic acid in both spinachchloroplasts and Avena leaves, in contrast to the effect ofcerulenin which inhibits de novo synthesis but not fatty acidelongation. On the other hand, TLM is less inhibitory to furtherelongation of stearic acid to very long chain fatty acids inpea seeds. The inhibition rate decreased in the order of synthesisof arachidic, behenic and lignoceric acid. (Received December 26, 1986; Accepted April 24, 1987)