Action spectra for light-induced germination in dormant lettuce seeds

Fluence response curves for red light-induced germination of thermodormant (TD) seeds of Lactuca sativa L. show two regions that differ in their light sensitivity. In the region of high sensitivity, the germination responses differ between seed batches and can be altered by dark storage or far red irradiation. Induction of germination in far red dormant (FRD) seeds requires far higher fluences. Action spectra for induction to 60% germination were determined for these various response types. Spectra for the regions of low sensitivity response are similar for TD and FRD seeds. In comparison, the action spectrum for the highly sensitive response in TD seeds is significantly shifted to longer wavelengths. Analogous differences exist in the action spectra for far red reversal of the red induced germination responses. Germination induction in the low sensitivity region shows repeated red-far red reversibility. Far red reversal of red induction in the high sensitivity region does not saturate even at the highest far red fluences available and requires increased red fluences for subsequent reinduction. A model quantitatively accounting for these observations is presented. It is pointed out that action spectra of processes involving photoreversible pigments with partly overlapping absorption spectra in general are not identical with the absorption spectra of the partners. They should depend upon the degree of phototransformation required to elicit a given physiological response. In the case of induction of lettuce seed germination the observed action spectra can be interpreted as reflecting different requirements for P _fr of the various response types. Our results do not necessitate the assumption of spectroscopically different forms of phytochrome in these seeds.Abbreviations TD thermodormant - FRD far red dormant - P phytochrome - P _r red absorbing form of P - P _fr far red absorbing form of P     

Growth physics and water relations of red-light-induced germination in lettuce seeds

Red light (R) and gibberellins (GA) each induce a water potential decrease in the axes of lettuce (Lactuca sativa L.) embryos resulting in germination of intact seeds (achenes) or an increase in growth of the axes of isolated embryos. The fruit coat and endosperm are a substantial barrier to the penetration of exogeneous GA. Isolated embryos take up 35 times as much [³H]GA₁ as the embryos of intact seeds and respond to less than 1·10^-10 M GA₃ or GA₄₊₇. We calculated that only 1·10^-8 M of either GA₃ or GA₄₊₇ would result in 50% germination if the GA were able freely to penetrate the fruit coat. Exogenous GA₃ or GA₄₊₇, at concentrations insufficient to cause germination, result in an apparent synergistic promotion of germination when suboptimal R is applied. Yet suboptimal concentrations of exogenous GA₃ or GA₄₊₇ and suboptimal R result in only additive increases in the growth response in axes of isolated embryos. Dose-response curves demonstrate quantitative increases in the growth response of the isolated axes after R or GA treatments insufficient to induce germination in intact seeds, indicating that a threshold potential must be achieved by the embryonic axes before germination can occur.Abbreviations FR far=red light - GA gibberellin - PEG poly-ethylene glycol 4000 - P_fr far-red-absorbing phytochrome - R red light III.=Carpita et al. 1979b; IV.=Carpita et al. 1979c     

Overcoming dormancy in seeds with ethanol and other anesthetics

Dormancy in fall panicum (Panicum dichotomiflorum Michx.) caryopses (seeds) is overcome by imbibition at 35° C in ethanol solutions. Whereas germination in the absence of ethanol depends on active phytochrome, the seeds may germinate in darkness after treatment with 0.2 to 0.5 M ethanol. Ethanol overcomes dormancy also in seeds of several other weedy grass species. Ethyl ether, chloroform, methanol, and acetone act similarly to ethanol. We suggest that this action depends on modifyng the properties of a membrane(s) in a manner related to the actions of other anesthetics.     

Adenosylhomocysteinase and adenosine nucleosidase activities in Lupinus luteus cotyledons during seed formation and germination

The activities of adenosylhomocysteinase (EC 3.3.1.1) and adenosine nucleosidase (EC 3.2.2.7) were assayed in extracts from yellow lupin (Lupinus luteus L.) cotyledons at different stages of seed formation and seedling development. Adenosylhomocysteinase activity was demonstrated in all the cotyledon extracts examined. Its lowest level was found in the dry seeds and the highest, in 4-day-old seedling cotyledons. Extracts from the cotyledons of maturating seeds, dry seeds, and seedlings up to the second day of growth exhibited no adenosine nucleosidase activity. Adenosine nucleosidase activity appeared in the cotyledons of 2-day-old seedlings and its highest level was reached in 4-to 5-day-old seedlings. There is no inhibitor of adenosine nucleosidase in the maturating and dry yellow lupin seeds. No activator of a possible zymogen form of adenosine nucleosidase from maturating or dry seeds occurs in the growing seedlings.     

Development of cytosol and chloroplast aldolases during germination of spinach seeds

The total activity of aldolase (EC 4.1.2.13) and the activities of cytosol and chloroplast aldolase were determined in seeds, cotyledons, primary leaves and secondary leaves of spinach (Spinacia oleracea L., cv. Monopa) during germination. Total aldolase activity in cotyledons increased from low levels to a low maximum in the dark after one week and to a high maximum in white light after three to four weeks and declined thereafter. The activity in primary and secondary leaves started to rise strongly from the 18th and 26th days, respectively, up to the 42nd day of germination. The levels of aldolase activity paralleled the development of leaf area, chlorophyll content and protein content per leaf except that the leaf area of cotyledons continued to increase steadily up to the 42nd day after the maximum of aldolase activity was reached. Resolution of cytosol- and chloroplast-specific isoenzymes by chromatography on diethylaminoethylcellulose indicated that in the light the cytosol enzyme represented approx. 8% of the total activity in cotyledons, primary and secondary leaves throughout germination, and the chloroplast enzyme represented the remaining 92%. Only in cotyledons of dark-grown seedlings was the cytosol aldolase between 25 and 50% of the total activity. Seeds contained almost exclusively a cytosol aldolase. In cotyledons the increase of total activity in the light was specifically the consequence of an increase in chloroplast aldolase while the cytosol aldolase was little affected by light. The light effect was mediated by phytochrome as demonstrated by classical induction and reversion experiments with red and far-red light and by continuous far-red light treatment.Abbreviation DEAE-cellulose diethylaminoethylcellulose     

An ATP-synthesizing system in seeds

Using onion seed powder, a semi-in vitro system for ATP synthesis in seeds has been developed. The system requires AMP, phosphoenolpyruvate (PEP) and orthophosphate with apparent Km values of 0.8, 1.5 and 3.0 mM, respectively. ATP synthesis is pH-dependent with a sharp optimum at pH 6.4, it exhibits linearity with time up to 40 min, and with a seed powder concentration between 25 and 150 mg ml^-1. The system is stimulated by low concentrations (<25 mM) of K⁺ and Mg²⁺ but is inhibited by higher concentrations of K⁺ and Mg²⁺ as well as by low concentrations of Li⁺, Na⁺ and especially Ca²⁺. The maximal rate is about 5 pmol min^-1 mg seed powder^-1 in dry onion seeds. During seed imbibition the rate of activity increases by about 120% after 3 h, reaching a plateau which is steady up to 18 h, when the radicle emerges. A comparison of the ATP content in seeds during the early period of imbibition with the capacity of ATP synthesis at this stage reveals that the described system could provide, during germination, 100 times more ATP than that found in imbibed seeds. The system is shown to be present in ten different types of seeds.     

The growth physics and water relations of red-light-induced germination in lettuce seeds

Using lettuce (Lactuca sativa L., cv. Grand Rapids) embryos in osmotica, we have demonstrated that when the growth rates of the embryonic axes of seeds treated with red (R) or far-red (FR) light are equalized, the axes of R-treated seeds develop a 3.4-bar decrease in water potential (paper No. III).As axial growth begins, reserve protein and phytin decrease rapidly, concomitant with increases in reducing sugars, -amino nitrogen, and inorganic and esterified soluble phosphates. However, no differences between the axes of R-and FR-treated seeds are found with respect to the changes in these compounds, indicating that these changes arise as a result of growth and are not under immediate phytochrome control. Little change in the total lipid content is found in either treatment. The axes of FR-treated seeds hydrolyze endogenous sucrose at a greater rate thant those of R-treated seeds. Axes of R-treated seeds accumulate K⁺ and Na⁺ to a greater extent than those of FR-treated seeds. When potassium salts are added to the incubation medium, R induces increased K⁺ uptake by the axis and greater medium acidification by the axis. Malate and other organic acids and acidic amino acids increase at equal rates in both treatments, indicating that inorganic anions may also be taken up to balance the ionic charges. The results are compatible with the assumption that changes in the osmotic and pressure potentials of the embryonic axes of R-treated seeds are the result of a phytochrome-stimulated proton pump which, in whole dormant seeds, would initiate water-potential changes allowing the embryos to overcome the mechanical restraint of the surrounding seed layers, resulting in germination.Abbreviations FR far-red light - PEG polyethylene glyeol 4000 - Pfr far-red-absorbing form of phytochrome - R red light III=Carpita et al. 1979     

The control of food mobilization in seeds of Cucumis sativus L.

An analysis of the in vitro activities of proteolytic enzymes from cotyledons of germinating cucumber seeds has been carried out and the effects of protein degradation products on such activities monitored. Aminopeptidase activity is substantially inhibited with either L-leucine or L-phenylalanine and trypsin activity with L-arginine. Aminopeptidase activity was also markedly reduced in the presence of individual di- and tripeptides. Of the peptides tested, however, only L-tryptophyl-L-phenylalanine inhibited the degradation of native cucumber seed protein by the endogenous cucumber seed protease(s) (autodigestive activity).Abbreviations TCA trichloroacetic acid - L-leuglygly L-leucylglycylglycine - L-pheglygly L-phenylalanylglycylglycine - L-phe-L-leu L-phenylalanyl-L-leucine - L-leu-L-phe L-leucyl-L-phenylalanine - L-tryp-L-phe L-tryptophyl-L-phenylalanine - LPA L-leucine-p nitroanilide - BAPNA -N-benzoyl-DL-arginine-p nitroanilide - ADA autodigestive activity     

Effects of abscisic acid,gibberellic acid and fusicoccin on the transmembrane potential during the early phases of germination in radish (Raphanus sativus L.) seeds

During germination, the transmembrane electric potential (PD) of cortical cells of the embryonal axis of radish seeds (Raphanus sativus L.) rises from-120 mV initially to a maximum of-150 mV after 5 h incubation, then falls again to stable values of around-120 mV. Treatments inhibiting germination block the transitory PD increase. Administration of uncoupling agents or low temperatures, during the process of germination, produces a marked fall of the PD transitory increase. Abscisic Acid has a parallel inhibitory effect on PD and germination, while fusicoccin produces a rise in both; administration of abscisic acid with fusicoccin inhibits germination, while the PD remains at the high levels given by fusicoccin. These results are discussed in relation to ion exchange at membrane level.Abbreviations ABA abscisic acid - FC fusicoccin - GA₃ gibberellic acid - PD electric potential difference (between the vacuole and the external medium) - CH cycloheximide - DNP dinitrophenol - FCCP (p-trifluormethoxy)-carbonylcyanide-phenylhydrazone - DCCD N,N-dicyclohexylcarbodiimide     

Spatially regulated genes expressed during seed germination and postgerminative development are activated during embryogeny

Summary We investigated the control of genes expressed primarily during seed germination and postgerminative development in Brassica napus L. We identified cloned mRNA sequences which became prevalent within 1 day after the start of imbibition and were at low or undetectable levels in immature embryos, dry seeds, and leaves. Most postgermination-abundant mRNAs accumulated primarily, though not exclusively, in different parts of the seedling. Of the 14 cloned mRNAs, 8 were prevalent in cotyledons, 2 were abundant in seedling axes, and 4 were approximately equally distributed in both parts. We showed that although these mRNAs reached maximal levels in seedlings, the spatially regulated mRNAs were also detected at distinct embryonic stages; mRNAs prevalent in seedling axes accumulated primarily during early embryogenesis while cotyledon-abundant mRNA concentration increased during late embryogeny. We conclude that the temporal and spatial regulation of gene expression in seedlings reflects similarities and differences in the physiological functions of cotyledons and axes. Furthermore, the regulated expression of cotyledon-abundant genes during late embryogeny suggests that the mRNAs and possibly proteins may accumulate in preparation for subsequent seedling growth. Similarities in the accumulation of cotyledon-abundant mRNAs may indicate coordinate regulation of this gene set.Abbreviations DAF days after flowering - DAI days after the start of imbibition - HAI hours after the start of imbibition - kb kilobase(pairs)     

Dormancy in somatic embryos and seeds ofVitis: changes in endogenous abscisic acid during embryogeny and germination

Abscisic acid (ABA) in extracts of somatic embryos and seeds of Gloryvine (Vitis vinifera L.xV. rupestris Scheele) was measured by gas chromatography-mass spectrometry-selected ion monitoring using deuterated ABA, (±)-[C-3Me-²H₃]ABA, ([²H₃]ABA) as internal standard. The ABA content increased rapidly during embryogeny (0.035 ng/embryo at the globular stage to 0.22 ng/embryo at the mature stage). The level of ABA in the tissues of somatic embryos, expressed in ng/mg dry weight, decreased from the globular stage (0.76 ng/mg) to the mature stage (0.25 ng/mg). Chilling (4° C) induced normal germination of seeds and mature somatic embryos and precocious germination of globular, heart-shaped and torpedoshaped somatic embryos. In all cases chilling led to a marked reduction in endogenous ABA. Exogenous (±)-ABA inhibited the germination of chilled somatic embryos.Abbreviations ABA abscisic acid - [²H₃]ABA (±)-[C-3Me-²H₃]-abscisic acid - BHT 2,6-di-t-butyl-4-methylphenol - GC-MS gas chromatography-mass spectrometry - Me-ABA and Me-[²H₃]ABA methyl esters of ABA and [²H₃]ABA, respectively - SIM selected ion monitoring     

Changes in germination and respiratory potential of embryos of dormant Grand Rapids lettuce seeds during long-term imbibed storage,and related changes in the endosperm

Grand Rapids lettuce (Lactuca sativa L.) seeds were stored in an imbibed state for up to two years. Embryos dissected from stored seeds showed a progressive loss with time in their ability to germinate on polyethylene glycol (PEG) solutions. Little germination of dissected embryos from one-month imbibed seeds occurred on-6 bar PEG but only after four months of storage did the dissected embryos fail to germinate on-4 bar PEG. After two years storage 30% of dissected embryos still were able to germinate on-2 bar PEG. This loss of germination potential, which may be a symptom of the development of an embryo dormancy, could be reversed by N⁶-benzyladenine (BA) and red light (R) applied together or separately to dissected embryos. Two weeks of chilling of 12-month imbibed seeds restored sensitivity to R and a 48-h BA pretreatment prior to R resulted in germination rates similar to those of seeds emerging from primary dormancy. There was loss of embryo control of endo--mannanase activity after two weeks of storage even though the endosperms themselves retained their capacity for enzyme synthesis for six more weeks. Eventually, then, endo--mannanase synthesis is not possible because of inherent changes in both the embryo and endosperm, although each tissue undergoes changes at its own rate. Oxygen uptake by embryos dissected from two-month imbibed seeds did not increase to the same extent as embryos dissected from freshly imbibed seeds. In intact seeds germinating from a skotodormant state, oxygen uptake increased at a time coincident with radicle protrusion, but did not achieve the levels of uptake of those seeds germinating from a primary dormant state. The decline in uptake of oxygen by secondary dormant seeds is the result of a lowered respiratory capability of the embryo itself, rather than of changes in permeability of the surrounding structures.Abbreviations BA N⁶-benzyladenine - Pfr active (far-redabsorbing) form of phytochrome - R red light - PEG polyethylene glycol     

Gibberellins in mature apple seeds — contaminants?

Evidence is presented that gibberellins A₄ and A₇, previously identified (Sinska, I., Lewak, St., Gaskin, P., MacMillan, J., Planta 114, 359–364, 1973) in extracts of mature apple (Pyrus malus L.) seeds, were present primarily as contaminants. The facts supporting this conclusion are: a) the ratio of GA₄ to GA₇ was similar to that of a standard mixture; b) the concentrations were extremely high; and c) the ratio of GA₄ to GA₇ did not change during stratification, as had been reported when extracts were bioassayed (Sinska, I., and Lewak, St., Physiol. Vég. 8, 661–667, 1970).Michigan Agricultural Experiment Station Journal Article No. 9036     

Disappearance of stored polyadenylic acid and mRNA during early germination of radish (Raphanus sativus L.) embryo axes

Polyadenylic acid [poly (A)] is detected, characterized and quantitated in dry radish embryo axis RNA using a ³H poly (U) probe. The amount of poly (A) gradually decreases after the onset of soaking, and, after a few hours, recovers to the initial level. This variation is shown to result from the addition of two opposed phenomena: the decay of stored poly (A) and the accumulation of newly synthesized poly (A). Stored poly (A), as well as the in vivo protein synthesis coded for by preformed mRNA, decreases during early germination with a half-life of two hours. As a whole, these results demonstrate that at least a fraction of the stored mRNA is translated as soon as the seed is soaked and that its role is rapidly taken over by newly-made mRNA.Abbreviations Poly (A) (+) RNA polyadenylated RNA - Poly (A) polyadenylic acid - Poly (U) polyuridylic acid     

Differences in properties of peanut seed lectin and purified galactose- and mannose-binding lectins from nodules of peanut

Two lectins were purified by affinity chromatography from mature peanut (Arachis hypogaea L.) nodules, and compared with the previously characterised seed lectin of this plant. One of the nodule lectins was similar to the seed lectin in its molecular weight and amino-acid composition and ability to bind derivatives of galactose. However, unlike the seed lectin, this nodule lectin appeared to be a glycoprotein and the two lectins were only partially identical in their reaction with antibodies prepared against the seed lectin. The other nodule lectin also appeared to be a glycoprotein but bound mannose/glucose-like sugar derivatives, and differed from the seed lectin in molecular weight, antigenic properties and amino-acid composition.Abbreviations Gal galactose - Gle glucose - GNL galactose-binding nodule lectin - Fru fructose - MNL mannosebinding nodule lectin - M _r rerative molecular mass - PBS phosphate-buffered saline - PSL peanut seed lectin - SDS sodium dodecyl sulphate - Sorb sorbitol     

Detection of lectins in nodulated peanut and soybean plants

The direct double-antibody enzymelinked immunosorbent assay system was used in the detection and measurement of seed lectins from peanut (Arachis hypogaea L.) and soybean (Glycine max L.) plants (PSL and SBL, respectively) that had been inoculated with their respective rhizobia. Concentrations of PSL dropped to undetectable levels in peanut roots at 9 d and stems and leaves at 27 d after planting; SBL could no longer be detected in soybean roots at 9 d and in stems and leaves at 12 d. A lectin antigenically similar to PSL was first detected in root nodules of peanuts at 21 d reaching a maximum of 8 g/g at 29 d then decreasing to 2.5 g/g at 60 d. There was no evidence of a corresponding lectin in soybean nodules.Sugar haemagglutination inhibition tests with neuraminidase-treated human blood cells established that PSL and the peanut nodule lectin were both galactose/lactose-specific. Further tests with rabbit blood cells demonstrated a second mannosespecific lectin in peanut nodule extracts that was not detected in root extracts of four-week-old inoculated plants or six-week-old uninoculated plants, although six-week-old root extracts from inoculated plants showed weak lectin activity. The root extracts from both nodulated and uninoculated plants contained another peanut lectin that agglutinated rabbit but not human blood cells. Haemagglutination by this lectin was, however, not inhibited by simple sugars but a glycoprotein, asialothyroglobulin, was effective in this respect.Abbreviations DAS double antibody sandwich - ELISA enzyme-linked immunosorbent assay - PBS phosphate-buffered saline - PSL peanut seed lectin - SBL soybean lectin     

Light effects upon dry lettuce seeds

Germination of certain dry seeds (achenes) of Lactuca sativa L. cv. Grand Rapids was increased to ca. 75% after irradiation with 665 nm red light (R; 1x10³ J m^-2); this response was eliminated by far-red light (FR) following the R. The response of dry seeds required an order of magnitude more light than that of wetted seeds, and was not maximal until 48 h after irradiation. Other seeds, which could not be stimulated by R in dry state, showed a partial response after 10 min hydration. Irradiation of dry seeds (or seeds wetted 1 h) with FR (1x10³ J m^-2) reduced dark germination from 26% to 2%. Seeds dehydrated in an oven (60°C, 90 min) showed a decrease in germination if irradiated with R (1x10⁵ J m^-2) before wetting. The results show that phytochrome is present in dry lettuce seeds (and functional in some seed lots) prior to wetting; and that in other seed lots the molecule becomes functional within minutes after wetting the seeds. Transformation of the FR absorbing from of phytochrome (P_FR) to the inactive from (P_R) occurs at lower seed moisture content than the reverse reaction. It appears that dormancy in seeds ripened in sunlight might be assured during seed drying and maturation by the more effective transformation of P_FR to P_R than vice versa as phytochrome is dehydrated.Abbreviations FR far-red - R red - CAL seeds from California - NC seeds from North Carolina (see text)     

Inhibitory effects of full daylight on the germination of Lactuca sativa L.

Using glass filters that transmit various spectral bands and different intensities of natural daylight, experiments with achenes of lettuce cv. Vanquard were performed. Germination during prolonged treatment depended both on the far red/red radiation ratio and on the irradiance. The promotive effect of red radiation present in natural light prevailed at low irradiances, the inhibitory effect of far red radiation at high irradiances. The dormancy imposed by prolonged white light of high intensity can be cancelled by transferring the achenes to darkness or to diffuse weak white light. The effects are obviously of the high irradiance response type; they are exerted by the same mechanism that causes seed dormancy under leaf canopies. Some considerations on the ecological significance of seed behaviour are given.Abbreviations FR far red radiation - R red radiation - HIR high irradiance response - P_fr the far red absorbing form of phytochrome - P_r the red absorbing form of phytochrome     

Desaturation of oxygenated fatty acids in Lesquerella and other oil seeds

Species of the genus Lesquerella, within the Brassicaceae family, have seed oils containing hydroxy fatty acids. In most Lesquerella species, either lesquerolic (14-hydroxy-eicosa-11-enoic), auricolic (14-hydroxy-eicosa-11,17-dienoic) or densipolic (12-hydroxy-octadeca-9,15-dienoic) acid dominates in the seed oils. Incubations of developing seed from Lesquerella species with 1-¹⁴C-fatty acids were conducted in order to study the biosynthetic pathways of these hydroxylated fatty acids. [¹⁴C]Oleic (octadeca-9-enoic) acid, but not [¹⁴C]linoleic (octadeca-9,12-dienoic) acid, was converted into the hydroxy fatty acid, ricinoleic (12-hydroxy-octadeca-9-enoic) acid, which was rapidly desaturated to densipolic (12-hydroxy-octadeca-9,15-dienoic) acid. In addition, [¹⁴C] ricinoleic acid added to Lesquerella seeds was efficiently desaturated at the 15 carbon. A pathway for the biosynthesis of the various hydroxylated fatty acids in Lesquerella seeds is proposed. The demonstration of desaturation at position 15 of a fatty acid with a hydroxy group at position 12 in Lesquerella prompted a comparison of the substrate recognition of the desaturases from Lesquerella and linseed. It was demonstrated that developing linseed also was able to desaturate ricinoleate at position 15 into densipolic acid. In addition, the linseed 15 desaturase was able to desaturate vernolic (12,13-epoxy-octadeca-9-enoic) acid and safflower microsomal 12 desaturase was able to desaturate 9-hydroxy-stearate. Thus, hydroxy and epoxy groups may substitute for double bonds in substrate recognition for oil-seed 12 and 15 desaturases.Abbreviations GLC gas-liquid chromatography - lysoPC palmitoyl-lysophosphatidylcholine - PC phosphatidylcholine This work was supported by grants from Stifteisen Svensk Oljeväxtforskning, Skanska Lantmännen Foundation, Swedish Farmers Foundation for Agricultural research, The Swedish Natural Science Research Council and The Swedish Council for Forestry and Agricultural Research. Nicki Engeseth was supported by the National Science Foundation under a grant award in 1992.     

Lipid-body lipoxygenase is expressed in cotyledons during germination prior to other lipoxygenase forms

Lipid bodies are degraded during germination. Whereas some proteins, e.g. oleosins, are synthesized during the formation of lipid bodies of maturating seeds, a new set of proteins, including a specific form of lipoxygenase (LOX; EC 1.13.11.12), is detectable in lipid bodies during the stage of fat degradation in seed germination. In cotyledons of cucumber (Cucumis sativus L.) seedlings at day 4 of germination, the most conspicuous staining with anti-LOX antibodies was observed in the cytosol. At very early stages of germination, however, the LOX form present in large amounts and synthesized preferentially was the lipid-body LOX. This was demonstrated by immunocytochemical staining of cotyledons from 1-h and 24-h-old seedlings: the immunodecoration of sections of 24-h-old seedlings with anti-LOX antiserum showed label exclusively correlated with lipid bodies of around 3 m in diameter. In accordance, the profile of LOX protein isolated from lipid bodies during various stages of germination showed a maximum at day 1. By measuring biosynthesis of the protein in vivo we demonstrated that the highest rates of synthesis of lipid-body LOX occurred at day 1 of germination. The early and selective appearance of a LOX form associated with lipid bodies at this stage of development is discussed.Abbreviations DAPI 4,6-diamidino-2-phenylindole - DIC differential interference contrast - FITC fluorescein-5-isothiocyanate - LOX lipoxygenase This work was financially supported by the Deutsche Forschungsgemeinschaft, SFB 286 (I.F., A.N., H.K.) and SFB 363 (B.H., C.W.).