In vitro proliferation of saffron (Crocus sativus L.) stigma

Excised young intact stigmas plus ovaries of Crocus sativus L. were cultured on Linsmaier-Skoog media supplemented with either a cytokinin or an auxin alone or in combinations. Benzyladenine and kinetin at concentrations of 0.1, 1, and 5 mgl^-1 supported growth, and crocin was biosynthesized in the stigmas in vitro. Auxins had little effect. Young excised single stigmas or half ovaries were also cultured so as to form stigma-like structures in order to explore a possible new approach to industrial production of the spice, saffron. On Linsmaier-Skoog and Nitsch media supplemented with kinetin at concentration of 1 or 5 mgl^-1 and alpha-naphthalene acetic acid or indole-butyric acid at concentration of 0.1 or 10 mgl^-1 in combinations, stigma-like structures appeared directly and indirectly (through meristematic tissue), grew and matured. The maximum number of structures were 75 per half ovary. Three kinds of yellow pigments including crocin were tentatively identified by TLC in the stigma-like structures as was the case for the in vivo grown natural stigma, although the contents were lower.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxy-acetic acid - IAA indole-acetic acid - IBA indole-butyric acid - NAA alpha-naphthalene-acetic acid - TLC thin layer chromatography     

The effect of different night conditions on the CO2 fixation in a lichen Xanthoria parietina

CO₂ fixation was studied in a lichen, Xanthoria parietina, kept in continuous light, and with cyclic changes in light intensity, dark period or temperature. The diurnal and seasonal courses of CO₂ exchange were followed. The rate of net photosynthesis was observed to fall from morning to evening, and this decline was more pronounced in winter than in summer. The maximal net photosynthetic rate, 223 ng CO₂g^-1dws^-1, occured in winter and the minimum, 94 ng CO₂g^-1dws^-1, late in spring. The light compensation point in summer was four times as high as in winter. In continuous light (180 or 90 mol photons m^-2s^-1, 15°C) net photosynthesis decreased noticeably during one week, falling below the level maintained in a 12 h light: 12 h dark cycle. Photosynthetic activity did not decrease, however, in lichens held in continuous light (90 mol photons m^-2s^-1) with cyclic changes of temperature (12 h 20 °C: 12 h 5 °C). Active photosynthesis was also maintained in light of cyclically changing intensity (12 h: 12 h, 15 °C) when night-time light was at least 75% lower than illumination by day. A dark period of 4 hours in a 24-h light:dark cycle was sufficient to keep CO₂ fixation at the control level. It seems that plants need an unproductive period during the day to survive and this can be induced by fluctuations in light and/or temperature.     

THE COMBINED EFFECTS OF LOW TEMPERATURE AND SO2+NO2 POLLUTION ON THE NEW SEASON'S GROWTH AND WATER RELATIONS OF PICEA SITCHENSIS

Picea sitchensis (Bong.) Carr. seedlings were exposed to SO₂, NO₂ and SO₂+ NO₂ during dormancy in controlled environments, and were taken to night temperatures of 4, 0, −5, −10 and −15 °C in a freezer. Conditions in the freezer were carefully monitored during the low–temperature treatments. In two experiments, different photoenvironments and temperature regimes were imposed prior to the cold treatments, and different effects were observed. In the first, only limited frost hardiness was achieved and night temperatures of −15 °C were lethal. Temperatures of −5 and − 10 °C led to poor survival of lateral buds, particularly in plants exposed to 45 ppb SO₂. The poor bud break in plants exposed to SO₂ and to − 5 °C resulted in a loss of the effectiveness of this temperature as a chill requirement. Pressure-volume analysis showed that the shoots of plants exposed to NO₂ had greater elasticity (lower elastic moduli, e), so that loss of turgor occurred at lower relative water contents. In contrast, a hardening period (2 weeks in night/day temperatures of 3/10 °C and 8 h days at 50 μmol m⁻² s⁻¹ PAR) gave decreased elasticity and lower solute potentials of spruce shoots. In the second experiment, exposure to 30 ppb SO₂ and SO₂+ NO₂ led to slight, but consistent, increases in frost injury to the needles of plants frozen to − 5 and − 10 °C. The results suggest that the main interaction of low temperatures and winter pollutants may be on bud survival rather than on needle damage, but that effects are subtle, only occurring with certain combinations of pollutant dose and cold treatment.     

Expression of heterologous genes for wall teichoic acid in Bacillus subtilis 168

Summary A localized region of low DNA sequence homology was revealed in two strains of Bacillus subtilis by a specific 100-fold reduction in transformation by W23 DNA of the tag1 locus, a teichoic acid marker of strain 168. Fifty nine rare recombinants, hybrid at this locus, had all acquired donor-specific phage resistance characters, while losing those specific to the 168 recipient. Chemical analysis of isolated cell walls showed that these modifications are associated with major changes in the wall teichoic acids. Genetic analysis demonstrated that determinants for the ribitol phosphate polymer of strain W23 had been transferred to 168, replacing those for the glycerol phosphate polymer in the recipient. All W23 genes coding for poly(ribitol phosphate) in the hybrids and those specifying anionic wall polymers in strain 168 are clustered near hisA. In addition to tag1, the region exchanged extends just beyond gtaA in some hybrids, whereas in others it may include the more distant gtaB marker, encompassing a region sufficient to contain at least 20 average-sized genes. Surface growth, flagellation, transformability and sporulation all appeared normal in hybrids examined. Recombinants without a major wall teichoic acid from either strain were not found, suggesting that an integral transfer of genes for poly(ribitol phosphate) from W23 had occurred in all hybrids isolated. We interpret these results as indicating an essential role for anionic wall polymers in the growth of B. subtillis.     

Mechanism of phosphorus-induced zinc deficiency in cotton. III. Changes in physiological availability of zinc in plants Is mail

The effect of varied supply of P (2.5× 10⁻⁵ to 6× 10⁻⁴ M) and Zn (0 to 10⁻⁶ M) on uptake and concentrations of P and Zn was studied in cotton ( Gossypium hirsutum L. cv. Deltapine 15/21) grown in nutrient solution under controlled environmental conditions. At a given Zn supply, increasing levels of P had no significant effect on the concentrations of total Zn in plants. However, increasing levels of P induced or enhanced visual Zn deficiency symptoms when the Zn concentration in the nutrient solution was low. The concentrations of water-soluble Zn in roots and shoots constituted 60% of the total Zn concentrations for plants grown with low P and 30% for plants grown with high P. The concentration of water-soluble Zn in leaves, but not total Zn, was closely correlated with visual Zn deficiency symptoms, levels of chlorophyll, super oxide dismutase and membrane permeability. The critical deficiency concentration of water-soluble Zn in cotton leaves was in the range of 6 to 7 μg (g dry weight)⁻¹ or about 1.0 μg (g fresh weight)⁻¹. The results show that high P concentrations in plant tissue decrease the physiological availability of Zn. Water-soluble Zn in the tissue appears to be a suitable indicator for Zn nutritional status in general and phosphorus-induced Zn deficiency in particular. Also in field-grown orange trees (Citrus sinensis) visual Zn deficiency symptoms in leaves were closely related to the concentration of water-soluble Zn.     

Genetic diversity within and among 11 juvenile populations of green alder (Alnus crispa) in Canada

Germinated seeds from 11 populations of green alder [ Alnus crispa (Ait.) Pursh] sampled in four Canadian provinces were analysed for electrophoretically demonstrable diversity of 10 enzymes encoded by 15 structural loci. Of these, nine were polymorphic, and on average, 52% of the loci per population were polymorphic. Assuming a diploid model of expression, average level of expected heterozygosity was 0.11 with nearly all populations in Hardy-Weinberg equilibrium for the set of polymorphic loci analysed. No significant inbreeding and associated subpopulation structuring were noted. Rates of gene flow appeared high within and among populations. Although little divergence was observed among populations, genetic and geographical distances between populations were related. Discriminant and cluster analyses revealed a pattern of genetic variation associated with geography. Populations from northern Quebec were poorly differentiated, whereas western populations from Alberta exhibited a larger degree of genetic differentiation. Introgresive hybridization with the sympatric species Alnus sinuata (Regel) Rydberg and partial isolation in the West are suggested as an explanation for this larger differentiation. The occurrence and significance of rare alleles is discussed in relation to the importance of geographical distance in the process of population differentiation in this species.     

Gas exchange studies in two Portuguese grapevine cultivars

Gas exchange characteristics of leaves of Vitis vinifera L. cvs Tinta Amarela and Periquita, two grapevine cultivars grown in distinct climatic regions of Portugal, were studied under natural and controlled conditions. Daily time courses of gas exchange were measured on both a hot, sunny day and a cooler, partly cloudy day. Responses of net photosynthesis to irradiance and internal partial pressure of CO₂, were also obtained. A strong correlation between net photosynthesis (P_N) and leaf conductance (g_s) was found during the diurnal time courses of gas exchange, as well as a relatively constant internal partial pressure of CO₂ (P_i), even under non-steady-state conditions. On the cloudless day, both P_N and g_s were lower in the afternoon than in the morning, despite similar conditions of leaf temperature, air to leaf water vapor deficit and irradiance. The response curves of net photosynthesis to internal CO₂ showed linearity up to p_i values of 50 Pa, possibly indicating a substantial excess of photosynthetic capacity. When measured at low partial pressures of O₂ (1 kPa), P_N became inhibited at high CO₂ levels. Inhibition of P_N at high CO₂ was absent under normal levels of O₂ (21 kPa). Significant differences in gas exchange characteristics were found between the two cultivars, with T. Amarela having higher rates under similar measurement conditions. In particular, the superior performance of T. Amarela at high temperatures may represent adaptation to the warmer conditions at its place of origin.     

The effect of lime on phosphorus adsorption and barley growth in three acid soils

For three acid soils from Santa Catarina, Brazil, lime application and time of incubation with lime had little effect on the adsorption of added phosphorus. In two soils with high contents of exchangeable aluminium, solution P and isotopically exchangeable P were decreased by incubating with lime for 1 month: phosphorus was probably adsorbing on freshly precipitated aluminium hydrous oxides. In one soil with less exchangeable aluminium, P in solution was increased by liming. After 23 months lime increased solution and exchangeable P possibly due to crystallization of aluminium hydrous oxides reducing the number of sites for P adsorption. All these changes were however small. In a pot experiment, lime and phosphorus markedly increased barley shoot and root dry matter and P uptake. Although liming reduced P availability measured by solution P, isotopically exchangeable P and resin extractable P, it increased phosphorus uptake by reducing aluminium toxicity and promoting better root growth. The soil aluminium saturation was reduced by liming, but the concentration of aluminium in roots changed only slightly. The roots accumulated aluminium without apparently being damaged.     

Prediction of heavy-metal concentrations in mature plants by chemical analysis of seedlings

Five plant species were cultivated on a soil from the Neckar alluvial fan near Heidelberg (FRG) polluted by the emissions of a cement plant. Thallium, cadmium and lead concentrations in seedlings and mature plants were determined by atomic absorption analysis. AdditionallyBrassica napus L.napus was grown on soils containing 5 different concentrations of heavy metals, achieved by mixing two similar soils, from the same area but with different metal concentrations. Thallium and cadmium were shown to be taken up by roots whilst lead which was also absorbed, was deposited mainly on the plant surface. However during cultivation in the winter months, a remarkable deposit of lead via the roots was found. Thallium in the soil from a anthrorogen source was more available to plants than thallium of geological origin. During the lifetime of a plant concentrations of thallium and cadmium were always highest in the seedling. The decrease in metal concentration with maturity depended on the plant species and the element, but was not a function of the metal concentration in the soil.