Grain filling in relation to monocarpic senescence of wheat in varying source-sink ratios

Flag leaf removal at any stage of grain growth hastened senescence (reduction in chlorophyll content) of the sterile glumes whereas a removal of the latter did not alter senescence of the former. Kernel mass, grain mass per ear, harvest index and sink activity reduced more conspicuously by the removal of glumes than by the flag leaf removal. Removal of grains hastened senescence of the glumes only, although protein content increased at a later grain removal in the majority of source organs. Moisture contents of the developing grains were mostly reduced by the removal of either the flag leaf or the glumes, though flag leaf removal at anthesis affected it the most. Protein levels of the developing grains reduced at harvest only when the glumes were removed at anthesis but sugar levels in later phases always decreased irrespective of the time of removal and nature of the source organs.     

CNS depressive role of aqueous extract of Spinacia oleracea L. leaves in adult male albino rats

Treatment with Spinacia oleracea extract (SO; 400 mg/kg body weight) decreased the locomotor activity, grip strength, increased pentobarbitone induced sleeping time and also markedly altered pentylenetetrazole induced seizure status in Holtzman strain adult male albino rats. SO increased serotonin level and decreased both norepinephrine and dopamine levels in cerebral cortex, cerebellum, caudate nucleus, midbrain and pons and medulla. Result suggests that SO exerts its CNS depressive effect in PTZ induced seizure by modulating the monoamines in different brain areas.     

Availability of iodide and iodate to spinach (Spinacia oleracea L.) in relation to total iodine in soil solution

A greenhouse pot experiment was carried out to investigate the availability of iodide and iodate to soil-grown spinach (Spinacia oleracea L.) in relation to total iodine concentration in soil solution. Four iodine concentrations (0, 0.5, 1, 2 mg kg⁻¹) for iodide (I⁻) and iodate (IO₃⁻) were used. Results showed that the biomass productions of spinach were not significantly affected by the addition of iodate and iodide to the soil, and that iodine concentrations in spinach plants on the basis of fresh weights increased with increasing addition of iodine. Iodine concentrations in tissues were much greater for plants grown with iodate than with iodide. In contrast to the iodide treatments, in iodate treatment leaves accounted for a larger fraction of the total plant iodine. The soil-to-leaf transfer factors (TF_leaf) for plants grown with iodate were about tenfold higher than those grown with iodide. Iodine concentrations in soil solution increased with increasing iodine additions to the soil irrespective of iodine species. However, total iodine in soil solution was generally higher for iodate treatments than iodide both in pots with and without spinach. According to these results, iodate can be considered as potential iodine fertilizer to increase iodine content in vegetables.     

Cytokinins in tRNA Obtained from Spinacia oleracea L. Leaves and Isolated Chloroplasts

Cytokinin-active ribonucleosides have been isolated from tRNA of whole spinach (Spinacia oleracea L.) leaves and isolated spinach chloroplasts. The tRNA from spinach leaf blades contained: 6-(4-hydroxy-3-methyl-2-butenylamino)-9-β-d-ribofuranosylpurine (cis and trans isomers), 6-(3-methyl-2-butenylamino)-9-β-d-ribofuranosylpurine, and 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-β-d -ribofuranosylpurine (cis and trans isomers). A method for isolation of large amounts of intact chloroplasts was developed and subsequently used for the isolation of chloroplast tRNA. The chloroplast tRNA contained 6-(3-methyl-2-butenylamino)-9-β-d-ribofuranosylpurine and 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-β-d -ribofuranosylpurine (the cis isomer only). The structures of these compounds were assigned on the basis of their chromatographic properties and mass spectra of trimethylsilyl derivatives which were identical with those of the corresponding synthetic compounds. The results of this study indicate that ribosylzeatin was present in spinach leaf tRNA, but absent from the purified chloroplast tRNA preparation.     

Acclimation of photosynthesis to low temperature in Spinacia oleracea L. II. Effects of nitrogen supply

The photosynthetic capacity of leaves of N-sufficent plantsof Spinacia oleracea L. increases following transfer a constanttemperature of 10C for 10 d compared to plants maintained at25C. The effects of nitrogen nutrition on this low temperatureacclimation have been investigated in respect of CO₂ assimilation,the activities and activation states of key enzymes and thepartitioning of recently fixed carbon. N-deficiency greatlyrestricted acclimation of photosynthetic CO₂ assimilation tolow temperature at both ambient and at saturating CO₂ concentrations,indicating a restriction on accilmatory changes in both ribulose1,5-bisphosphatecarboxylase-oxygenase (Rubisco) and the reactions of ribulose1,5-bisphosphateregeneration. Nitrogen limitation led to an increase in thepartitioning of recently-fixed carbon into starch. Total proteinincreased during acclimation in both N-sufficient and N-deficientleaves and was much less affected than were the activities ofenzymes. Increases in the activation state of Rubisco and thestromal fructose-1,6-bisphosphatase occurred in response tolow temperature, but increases in the activities of Rubisco,sucrose-phosphate synthase or the cytosolic fructose1,6-bisphosphatasecould not be sustained in N-deficient plants throughout theperiod of acclimation, although the activities of these enzymesdeclined less precipitately than in non-acclimated N-deficientplants. These data are all consistent with the view that increasesin the activities of key enzymes of carbon assimilation area pre-requisite for acclimation to low temperature and thatthese increases are restricted under N-limitation. Key words: Low temperature, nitrogen, photosynthesis, Rubisco, sucrose-phosphate synthase     

Sexual modification of female spinach seeds (Spinacia oleracea L.) by irradiation with ion particles

The female seeds of a spinach plant (Spinacia orelacea L.) were exposed to He (12.5 MeV/n) and C (18.3 MeV/n) ions in order to investigate the effects of ion particles on sex expression. He ions did not affect germination rates or flowering at doses up to 50 Gy. C ions did not affect germination rates or flowering at doses up to 15 Gy, but a dose of 25 Gy resulted in many plants with morphological aberrations. When unexposed female plants were grown without cross-fertilization for 10 weeks after sowing, 5.6-14.3% of the plants produced anthers from female flowers. These sex-modified plants could self-pollinate and form seeds, which expressed only female organs. Conversely, gynomonoecious plants were induced from these female seeds by exposure to He ions (5-50 Gy) and C ions (5-25 Gy) without any difference in the rates of flowered progeny. Moreover, andromonoecious plants were induced from female seeds by exposure to He ions at 50 Gy. These results suggest that the sex of a spinach plant is expressed as a flexible phenotype, converging from female to gyno- and andromonoecy after exposure to ion particles.     

菠菜种子胰蛋白酶抑制剂的分离纯化与部分性质研究

以菠菜种子为材料,经脱脂、酸性溶液抽提、热变性、硫酸铵分部沉淀得到胰蛋白酶抑制剂粗提物。再经离子交换、亲和层析和凝胶过滤,分离得到胰蛋白酶抑制剂SOTI,纯化倍数为57．22。SDS-PAGE测定其分子量约为22kD,等电聚焦测定其等电点为4．02。SOTI具有较高的热稳定性,在100℃处理后仍然具有一定的抑制活性。     

The effect of excess moisture on the germination of Spinacia oleracea L.

Summary The reversible inhibition of the germination of spinach (Spinacia oleracea L.) seeds in conditions which are even slightly wetter than optimal has been traced to the production, in a wet environment, of a layer of mucilage around and within the fruit coat which surrounds the true seed. Such wet seeds may however germinate readily when the temperature is lowered, or the oxygen pressure of the environment is raised, or the intact seeds are placed for a short time in hydrogen peroxide before being transferred to what normally would be an excess of water. Even in the absence of an increased oxygen supply the seeds will germinate under water provided the fruit coat, or even a small part of it where it covers the radicle, is crefully removed. No evidence has been found of a water soluble inhibitor and the findings are consistent with the hypothesis that germination is dependent on a sufficiently high rate of supply of oxygen to the sites embryonic respiration. The mucilage which is formed under wet conditions forms a barrier which prevents the transfer of oxygen to the embryo by gaseous diffusion or aqueous convection currents and restricts it to the process of aqueous diffusion, and under these conditions the rate of oxygen supply may not reach the threshold level required for germination.     

Isolation of sperm cells from mature pollen grains of Spinacia oleracea L.

Summary When mature pollen grains of Spinacia oleracea were squashed in a 25% sucrose solution and subsequently centrifuged on a percoll layer, sperm cells were isolated in high numbers. All steps were carried out at 4° C. Isolated sperm cells could be kept alive for several hours.     

Regulation of photosynthetic electron transport and photophosphorylation in intact chloroplasts and leaves of Spinacia oleracea L.

Oxygen ist reduced by the electron transport chain of chloroplasts during CO₂ reduction. The rate of electron flow to oxygen is low. Since antimycin A inhibited CO₂-dependent oxygen evolution, it is concluded that cyclic photophosphorylation contributes ATP to photosynthesis in chloroplasts which cannot satisfy the ATP requirement of CO₂ reduction by electron flow to NADP and to oxygen. Inhibition of photosynthesis by antimycin A was more significant at high than at low light intensities suggesting that cyclic photophosphorylation contributes to photosynthesis particularly at high intensities. Cyclic electron flow in intact chloroplasts is under the control of electron acceptors. At low light intensities or under far-red illumination it is decreased by substrates which accept electrons from photosystem I such as oxaloacetate, nitrite or oxygen. Obviously, the cyclic electron transport pathway is sensitive to electron drainage. In the absence of electron acceptors, cyclic electron flow is supported by far-red illumination and inhibited by red light. The inhibition by light exciting photosystem II demonstrated that the cyclic electron transport pathway is accessible to electrons from photosystem II. Inhibition can be relieved by oxygen which appears to prevent over-reduction of electron carriers of the cyclic pathway and thus has an important regulatory function. The data show that cyclic electron transport is under delicate redox control. Inhibition is caused both by excessive oxidation and by over-reduction of electron carriers of the pathway.     

ent-kaurene biosynthesis is enhanced by long photoperiods in the long-day plants Spinacia oleracea L. and Agrostemma githago L.

The effect of photoperiod on ent-kaurene biosynthesis was determined in the long-day (LD) plants spinach (Spinacia oleracea L.) and Agrostemma githago L. Further metabolism of ent-kaurene was blocked by application of the growth retardant tetcyclacis, and ent-kaurene accumulation was measured by isotopic dilution using gas chromatography-selected ion monitoring (GC-SIM) (E. Grosselindemann, J.E. Graebe, D. Stöckl, P. Hedden [1991] Plant Physiol 96: 1099-1104). In spinach, the rate of ent-kaurene accumulation in shoots grown under LD conditions was 3 times higher than in shoots grown under short-day (SD) conditions. ent-Kaurene also accumulated in fully expanded leaves, but at a lower rate than in shoots (15 and 55 pmol g-1 dry weight h-1, respectively). In Agrostemma, ent-kaurene accumulated at a rate 2.5 times higher in plants grown under LD conditions than in those grown under SD conditions. In spinach, enhanced ent-kaurene accumulation was detectable after 1 long day, and with exposure to additional long days, the rate of ent-kaurene accumulation increased further. Conversely, when plants were exposed to LD conditions and then returned to SD conditions, the rate of ent-kaurene accumulation decreased. Following tetcyclacis application, ent-kaurene accumulation was observed in all parts of spinach that were analyzed, but there were large quantitative differences between organs of different ages. As the leaves matured, ent-kaurene biosynthesis declined. Petioles accumulated more ent-kaurene than the corresponding leaf blades. It is concluded that stimulation of ent-kaurene biosynthesis by LD conditions leads to a higher rate of gibberellin biosynthesis, which is essential for stem elongation in rosette plants.     

Fractionation analysis and bioavailability of manganese in spinach (Spinacia oleracea L.) leaves

Abstract

This paper introduces a fractionation scheme using water, acetone, chloroform, diethyl ether, ethanol, n-hexane, and methanol as extractants for the determination of manganese in spinach samples by inductively coupled plasma-mass spectrometry (ICP-MS). Simulated gastric and intestinal digestions as well as n-octanol extraction and activated carbon adsorption were performed for the bioavailability assessments. Comparative studies of the various extraction treatments were evaluated for confirmation analysis. The total elemental concentrations were determined after digesting the samples in a microwave digestion system. The method validation parameters were defined in terms of the detection limits, accuracy, and precision. Additional validation was performed by comparing the ICP-MS method with atomic absorption spectrometry. The limits of detection and quantification were 0.046 and 0.154 mg kg^-1, respectively. Additionally, the repeatability and reproducibility, calculated from the relative standard deviation (%RSD), were 2.4% and 3.7%, respectively.     

菠菜性别相关 EST-SSR 标记的开发及应用

为了明确菠菜EST序列中SSR的总体特点,开发菠菜EST-SSR引物;为利用EST-SSR引物进行菠菜性别相关特异序列的克隆奠定基础,本文从NCBI上获得1093条EST,利用在线软件SSRIT检测所含SSR序列,并进行分析。共检索出68条SSR序列,分布于64条EST中,检出率为6.22%,包括22种重复基元。其中二核苷酸重复基元的EST-SSR占主导地位,占总SSR数目的32.3%。利用在线引物设计软件Primer3.0设计了7对EST-SSR引物,在适合的PCR反应体系下,分别以雌、雄菠菜DNA基因组为模板,对设计的EST-SSR引物进行筛选,结果显示以EST序列HS097148设计的一对引物从菠菜雌雄基因组中扩增出一条雄性特异的条带,表明通过菠菜EST-SSR引物获得菠菜性别相关特异序列是可行的。     

Ion Relations of Symplastic and Apoplastic Space in Leaves from Spinacia oleracea L. and Pisum sativum L. under Salinity

Salt tolerant spinach (Spinacia oleracea) and salt sensitive pea (Pisum sativum) plants were exposed to mild salinity under identical growth conditions. In order to compare the ability of the two species for extra- and intracellular solute compartmentation in leaves, various solutes were determined in intercellular washing fluids and in aqueously isolated intact chloroplasts. In pea plants exposed to 100 millimolar NaCl for 14 days, apoplastic salt concentrations in leaflets increased continuously with time up to 204 (Cl⁻) and 87 millimolar (Na⁺), whereas the two ions reached a steady concentration of only 13 and 7 millimolar, respectively, in spinach leaves. In isolated intact chloroplasts from both species, sodium concentrations were not much different, but chloride concentrations were significantly higher in pea than in spinach. Together with data from whole leaf extracts, these measurements permitted an estimation of apoplastic, cytoplasmic, and vacuolar solute concentrations. Sodium and chloride concentration gradients across the tonoplast were rather similar in both species, but spinach was able to maintain much steeper sodium gradients across the plasmamembrane compared with peas. Between day 12 and day 17, concentrations of other inorganic ions in the pea leaf apoplast increased abruptly, indicating the onset of cell disintegration. It is concluded that the differential salt sensitivity of pea and spinach cannot be traced back to a single plant performance. Major differences appear to be the inability of pea to control salt accumulation in the shoot, to maintain steep ion gradients across the leaf cell plasmalemma, and to synthesize compatible solutes. Perhaps less important is a lower selectivity of pea for K⁺/Na⁺ and NO₃⁻/Cl⁻ uptake by roots.     

Three species of arbuscular mycorrhizal fungi confer different levels of resistance to water stress in Spinacia oleracea L.

Arbuscular mycorrhizal fungi (AMF) are applied in agriculture to improve plant nutrition and confer better resistance to biotic and abiotic stresses. Spinacia oleracea L. is an economically important herbaceous crop characterized by limited tolerance to water stress. We compared the effects of three species of AMF belonging to the genus Glomus on gas exchange rates, growth and yield of spinach plants exposed to acute and prolonged water stress. Inoculated plants always gave better results than control (non-inoculated), stressed ones, being G. clarum the species that provided the significantly best effects and G. monosporum the less remarkable ones. Mycorrhizal inoculation is a valid tool to provide water stress resistance to horticultural crops, and experimental comparisons among different mycorrhizal strains can help to optimize the effect through the identification of specific associations.     

Higher recombination frequencies in female compared to male meisoses in Brassica oleracea

Linkage maps of the nine chromosomes of Brassica oleracea, based on 75 informative molecular markers, have been compared in first and second backcross progeny from a cross between two doubled haploid lines. The second backcross progeny showed greater recombination frequencies for 75% of the pairs of adjacent markers, but there was no obvious indication that this effect was localised to particular regions of the chromosomes. Four chromosomes increased in genetic length more than twofold, while overall, the total map was 66% longer. The possible causes of this discrepancy are analysed. A sex difference in chiasma distribution and/or frequency at meiosis is thought to be the most likely explanation. The implications of this finding for mapping and map-based applications are discussed.     

Sterols of male and female flowers of Cucumis sativus

Sterols of male and female flowers of Cucumis sativus L. were similar in composition. The principal compound was 24-ethyl-5-cholesta-7,22-dien-3-ol. Five other 5-⁷ were detected: 24-methyl-7-ene, 24-ethyl-7-ene, 24-ethyl-7,24(28)Z-diene, 24-ethyl-7,25-diene and 24-ethyl-7,22,25-triene. Small amounts of ⁵ (cholesterol, 24-methylcholesterol and 24-ethylcholesterol) were detected. The possible significance of these sterols is discussed.Abbreviations GLC gas-liquid chromatography - GC-MS combined gas chromatography-mass spectrometry     

Sequence Analysis of Cloned cDNA and Proteolytic Fragments for Nitrate Reductase from Spinacia oleracea L.

Proteolytic fragments were obtained by limited proteolysis of120 kDa nitrate reductase from Spinacia oleracea L. using trypsinand Staphylococcus aureus V8 protease. Determination of NH₂-terminalsequences in 9 to 14 Edman degradation steps allowed the exactlocalization of the fragments within the amino-acid sequenceof spinach nitrate reductase was deduced from the nucleotidesequence of cDNA clone pSPNR117 which was initially identifiedby hybridization to squash nitrate reductase cDNA clone [Crawford,¹N. M., Campbell, W. H. and Davis, R. W. (1986) Proc. Natl. Acad.Sci. USA 83: 8073] and anti spinach nitrate reductase polyclonalantibodies. This clone has a 2324 base insert, and the aminoacid sequence deduced from its open reading frame, which contains640 residues. The predicted sizes 42.5 and 30 kDa were in reasonableagreement with previous determination of the apparent molecularsizes of the FAD-cyt-chrome b557-binding, and FAD-binding fragments,respectively. Arginine residue was the cleavage site for trypsin and glutamicacid was for S. aureus V8 protease. The amino acid residueswithin the linker regions which connect the functional domains,could be cleaved with trypsin or S. aureus V8 protease may bewell conserved in the amino acid sequences deduced from thenitrate reductase cDNA sequences. A sequence identity of 61.2-80.1 % was found in the amino acidsequences deduced from the cDNA sequences as obtained by spinachand other higher plant nitrate reductases. However, the aminoacid sequences surrounding the proteolytic cleavage sites ofnitrate reductase had poor homology. (Received March 30, 1991; Accepted July 24, 1991)     

Isolation and Characterization of a Virus Inhibitor from Spinach (Spinacia oleracea L.)

A virus inhibiting protein (VI) was isolated from spinach (Spinacia oleracea L.). The VI inhibited infections of test plants with plus- and minus-strand RNA viruses. Inoculation of both local lesion and systemic hosts with TMV in the presence of varying amounts of the VI resulted in typical dose response curves for the number of local lesions or the amount of virus respectively. The lowest concentration of VI leading to a significant reduction in the number of local lesions was 0.06 μg/ml. The VI was found to inhibit local lesion formation only when applied within 2–3 h p.i. but still reduced the number of local lesions when applied up to 9 h prior to virus inoculation. The antiviral activity could be attributed to a protein of molecular weight 29,000 dalton with an isoelectric point of 10.3. Its activity was destroyed by heating for 30 min to 70°C. These characteristics resemble those of other virus inhibiting proteins described for members of the order Caryophyllales such as the Phytolacca inhibitor against which a serological relationship was obtained.     

Embryogenesis and plant regeneration of spinach (Spinacia oleracea L.) from hypocotyl segments

A system for somatic embryogenesis and plant regeneration of spinach from hypocotyl segments has been established. Callus was induced on solid media supplemented with 8.5–15.0 mg.l⁻¹ of indole-3-acetic acid and 3.46–34.64 mg.l⁻¹ gibberellic acid. Callus was then subcultured on different media (solid or liquid) with or without IAA, or continuously maintained on the initiating media. Somatic embryos were obtained in subcultures on IAA-containing media as well as in long-term cultures on initiating media. The best results were achieved in liquid subcultures. About 60% of plantlets survived after transplanting in pots.