The Relationships between Fertility and Contents of Gibberellic Acid, Sugars and Dry Mass in Apical Parts of Chara Vulgaris Thalli

The contents of endogenous gibberellic acid (GA₃), sugars, and dry mass in apical parts of fertile and sterile thalli of Chara vulgaris were estimated. The GA₃ concentration in the first node of fertile thallus, determined by capillary electrophoresis, was about 70.0 mg kg^–1 of fresh mass (f.m.). Pisum sativum-bioassay showed GA₃ concentration of 80.0 mg kg^–1 (f.m.) which was about 3 times higher than in the first node of sterile thallus. The higher amount of GA₃, glucose, and the lower starch content and dry mass in fertile plants than in sterile ones suggest the interdependence between fertility and contents of studied components.     

Effect of Salinity on Photosynthesis and Biochemical Characteristics in Mulberry Genotypes

Mulberry genotypes were subjected to salinity (0–12 mS cm^–1) in pot culture experiment. Chlorophyll and total carotenoid contents were reduced considerably by salinity. At low salinity, photosynthetic CO₂ uptake increased over the control, but it decreased at higher salinity. Contents of soluble proteins, free amino acids, soluble sugars, sucrose, starch, and phenols increased at salinity of 1–2 mS cm^–1 and decreased at higher salinity (8–12 mS cm^–1). Glycine betaine accumulated more than proline, the maximum accumulation of both was at salinity of 2–4 mS cm^–1. Among the genotypes studied, BC2-59 followed by S-30 showed better salinity tolerance than M-5.     

In vitro rosmarinic acid accumulation in sweet basil (Ocimum basilicum L.)

Leaf-derived suspension cultures of sweet basil, Ocimum basilicum L. accumulated rosmarinic acid up to 10 mg g^–1 dry wt, a value up to 11 times higher than in callus cultures or in leaves of donor plants. Immobilized cells accumulated less than 15 g rosmarinic acid g^–1.     

Seasonal growth of the submerged macrophyte Ceratophyllum demersum L. in mesotrophic Lake Vechten in relation to insolation,temperature and reserve carbohydrates

Seasonal growth of a Ceratophyllum demersum stand in Lake Vechten, The Netherlands, varied considerably during 1978, '79 and '81. The biomass was highest in 1981 (max. 115 g ash-free dry weight m^–2). The 1978 growth trend was similar to that of 1981 with slightly lower net annual production (max. 92 g AFDW m^–2). The vegetation almost disappeared in 1979 (max. 24 g AFDW m^–2). These large differences in biomass could not be explained by differences in insolation but were mainly attributed to the severe winter of 1978–'79 which slowed plant development and full maturity was attained only after the diurnal insolation had decreased.Reserve carbohydrates were primarily starch and water-soluble sugars. Starch concentrations varied between 71.5 and 24.7 mg g^–1 AFDW in the winter and summer, and total sugar concentrations between 24.9 and 20.2 mg g^–1 AFDW, respectively. The non-reducing sugars tended to predominate in summer and the reducing sugars in winter. The value of these reserves for maintenance, growth and survival was assessed by calculating plant carbon budgets for several seasons.It was concluded that C. demersum relies heavily on its developmental timing and energy-conserving physiological mechanisms to survive extended periods of stress and in these respects is analogous to a typical terrestrial shade plant.     

In vitro culture of Montanoa tomentosa for the production of diterpenic acids

Following a solid phase extraction, GC-MS and GC-FID procedures, the production of three kaurane derivatives (grandiflorenic, kaurenoic and monoginoic acids) was detected in callus and cell suspension batch cultures of Montanoa tomentosa. From different hormonal combinations, the addition of 0.5 mg 2,4-dichlorophenoxyacetic acid l^–1 + 2 mg kinetin l^–1 increased the accumulation of total kaurenoids in 6 months old calluses to 2.1 mg g^–1 dry weight and in cell suspensions cultures up to 0.76 mg g^–1 dry weight. Monoginoic acid, which has not been detected before in leaves of wild plants, accumulated in both in vitro systems.     

Chlorophyll content of seston in a regulated Rocky Mountain river,Idaho, USA

The chlorophyll content of seston at four sites in a regulated mid-order Rocky Mountain river, Henry's Fork of the Snake River, Idaho, USA, was examined. Spectrometry was used to determine the amount of chlorophyll a, b, c and in seston and potential organic matter sources including macrophytes, algae, plankton, and terrestial plant litter. The amount of chlorophyll in seston varied among size fractions, sites, and seasons. Coarse seston (6–1 mm) contained the most chlorophyll a (2.3 mg g^–1 ashfree dry mass [AFDM]) followed by ultra fine seston (53–0.3 µm; 1.9 mg g^–1 AFDM), very coarse seston (> 6 mm, 1.8 mg g^–1 AFDM), very fine seston (250–53 µm; 1.3 mg g^–1 AFDM), and fine seston (1–0.25 mm; 0.7 mg g^–1 AFDM). Chlorophyll content of coarse seston was similar at all sites reflecting a common source, aquatic macrophyte debris. Chlorophyll content of coarse and fine seston were highest in fall reflecting the importance of phenology of aquatic plants on sestonic pigment levels. Very fine seston from below a reservoir contained more chlorophyll than seston from downstream and tributary sites suggesting a reservoir source. Terrestial plant litter was chlorophyll depleted compared to autochthonous materials and seston. Most seston was autochthonously-derived from a variety of macrophyte, algal, and planktonic sources. The chlorophyll content of Henry's Fork seston was higher than that reported for similar rivers. Island Park Dam moderates river temperature and flow, enhances autotrophy, and accounts for the consistently high sestonic chlorophyll levels.     

Purification and properties of a novel raw starch degrading-cyclodextrin glycosyltransferase from Klebsiella pneumoniae AS- 22

A novel raw starch degrading α-cyclodextrin glycosyltransferase (CGTase; E.C. 2.4.1.19), produced by Klebsiella pneumoniae AS-22, was purified to homogeneity by ultrafiltration, affinity and gel filtration chromatography. The specific cyclization activity of the pure enzyme preparation was 523 U/mg of protein. No hydrolysis activity was detected when soluble starch was used as the substrate. The molecular weight of the pure protein was estimated to be 75 kDa with SDS-PAGE and gel filtration. The isoelectric point of the pure enzyme was 7.3. The enzyme was most active in the pH range 5.5–9.0 whereas it was most stable in the pH range 6–9. The CGTase was most active in the temperature range 35–50°C. This CGTase is inherently temperature labile and rapidly loses activity above 30°C. However, presence of soluble starch and calcium chloride improved the temperature stability of the enzyme up to 40°C. In presence of 30% (v/v) glycerol, this enzyme was almost 100% stable at 30°C for a month. The K_m and k_cat values for the pure enzyme were 1.35 mg ml⁻¹ and 249 μM mg⁻¹ min⁻¹, respectively, with soluble starch as the substrate. The enzyme predominantly produced α-cyclodextrin without addition of any complexing agents. The conditions employed for maximum α-cyclodextrin production were 100 g l⁻¹ gelatinized soluble starch or 125 g l⁻¹ raw wheat starch at an enzyme concentration of 10 U g⁻¹ of starch. The α:β:γ-cyclodextrins were produced in the ratios of 81:12:7 and 89:9:2 from gelatinized soluble starch and raw wheat starch, respectively.     

Growth and accumulation of storage reserves by somatic embryos of Ocotea catharinensis Mez. (Lauraceae)

The focus of this study was the assessment of in vitro growth of embryogenic cultures of Ocotea catharinensis Mez. (Lauraceae) on Woody Plant Medium (WPM) supplemented with 22.7 g l^–1 sorbitol, 2 g l^–1 Phytagel, 20 g l^–1 sucrose and 400 mg l^–1 glutamine and the biochemical analysis of somatic embryos at different developmental stages (globular, early cotyledonary, cotyledonary and mature). The embryoids underwent repetitive embryo-genesis and developed non-synchronously, throughout the culture period. Dry weight increased 12.6- and 26.8-fold after 3 and 5 weeks, respectively. During the 5 week culture period a reduction in the frequency of embryoids at the globular stage and increasing frequencies of embryoids at early cotyledonary, cotyledonary and mature stages were observed. Embryoids at the mature stages presented a small but significantly higher water content than those at the globular stage. Therefore, embryoid expansion at the latter stages of development was mainly due to water uptake. Embryoids at the globular stages accumulated higher levels of total proteins while those at the cotyledonary and mature stage showed higher levels of soluble sugars and starch (physiological markers of embryo maturation). Thus, significant differences in the profiles of accumulated storage reserves were detected in the embryoids at different developmental stages in the culture conditions tested.     

Interactive biosorption by microalgal biomass as a tool for fluoride removal

Maximum biosorption of Ca²⁺ was at 50 mg Ca²⁺ l^–1 with both Anabaena fertilissima (2.8 mg Ca²⁺ g^–1 dry wt) and Chlorococcum humicola (4.4 mg g^–1). Such Ca²⁺-treated biomasses, accumulated, respectively, 7 mg F g^–1 DW from an aqueous solution of 10 mg F l^–1 and 4.5 mg F g^–1 DW from 15 mg F l^–1. Data for both Ca²⁺ and F^– biosorption fitted the Langmuir adsorption isotherm indicating monolayer adsorption at a constant energy.     

Effects of lead and kinetin on the growth, and some physiological components of safflower

Pollution of the root environment with excess of Pb retarded shoot growth, decreased chlorophyll (Chl) content and reduced Chl stability (CSI) to heat. Plants growing in Pb polluted soil accumulated much more free amino acids and less soluble sugars than the control plants. Stability of leaf membranes to heat (51 °C) or dehydration stresses (40% polyethylene glycol, 6000) decreased in response to Pb pollution where the membranes of leaf discs excised from Pb-treated plants were damaged more than those taken from plants growing in Pb free soil. Supplying kinetin ameliorated the deleterious effects of Pb pollution on the parameters tested. Kinetin-treated plants had higher Chl, soluble sugars content and produced more biomass in their shoots. Also, kinetin increased leaf membrane stability especially in Pb-treated plants, effectively protected chlorophyll degradation by heat and increased Chl a and b stability index; the most effective concentration was 10 mg L^–1. The effects of Pb and kinetin as well as their interaction (Pb × Kin) on the parameters tested were statistically significant. Applied kinetin had a dominant role (as indicated by ²) in affecting shoot growth, soluble sugars, Chl a and b contents, stability of leaf membranes to dehydration stress as well as the Chl stability index. Pb had a dominant role on total free amino acids (TAA) and leaf relative water content (RWC). The interaction between Kin × Pb influenced the stability of leaf membranes to heat stress in a major way.     

The extrafloral nectaries of cowpea (Vigna unguiculata (L.) Walp.) II. Nectar composition,origin of nectar solutes,and nectary functioning

Nectar was collected from the extrafloral nectaries of leaf stipels and inflorescence stalks, and phloem sap from cryopunctured fruits of cowpea plants. Daily sugar losses as nectar were equivalent to only 0.1–2% of the plant's current net photosynthate, and were maximal in the fourth week after anthesis. Sucrose:glucose:fructose weight ratios of nectar varied from 1.5:1:1 to 0.5:1:1, whereas over 95% of phloem-sap sugar was sucrose. [¹⁴C]Sucrose fed to leaves was translocated as such to nectaries, where it was partly inverted to [¹⁴C]glucose and [¹⁴C]fructose prior to or during nectar secretion. Invertase (EC 3.2.1.26) activity was demonstrated for inflorescence-stalk nectar but not stipel nectar. The nectar invertase was largely associated with secretory cells that are extruded into the nectar during nectary functioning, and was active only after osmotic disruption of these cells upon dilution of the nectar. The nectar invertase functioned optimally (phloem-sap sucrose as substrate) at pH 5.5, with a starting sucrose concentration of 15% (w/v). Stipel nectar was much lower in amino compounds relative to sugars (0.08–0.17 mg g^-1 total sugar) than inflorescence nectar (22–30 mg g^-1) or phloem sap (81–162 mg g^-1). The two classes of nectar and phloem sap also differed noticeably in their complements of organic acids. Xylem feeding to leaves of a range of ¹⁴C-labelled nitrogenous solutes resulted in these substrates and their metabolic products appearing in fruit-phloem sap and adjacent inflorescence-stalk nectar. ¹⁴C-labelled asparagine, valine and histidine transferred freely into phloem and appeared still largely as such in nectar. ¹⁴C-labelled glycine, serine, arginine and aspartic acid showed limited direct access to phloem and nectar, although labelled metabolic products were transferred and secreted. The ureide allantoin was present in phloem, but absent from both types of nectar. Models of nectary functioning are proposed.     

Isolation and physiological study of an amylolytic strain of Lactobacillus plantarum

Summary An amylolytic lactic acid bacterium identified as Lactobacillus plantarum was isolated from cassava roots (Manihot esculenta var. Ngansa) during reting. The amylolytic enzyme synthesized was an extracellular -amylase with an optimum pH of 5.0 and an optimum temperature of 55° C. Cultured on starch, the strain displayed a growth rate of 0.43 h^–1, a biomass yield of 0.19 g·g^–1 and a lactate yield of 0.81 g·g^–1. The growth kinetics were similar on starch and glucose. Sufficient enzyme was synthesized and starch hydrolysis was not a limiting factor for growth. Biosynthesis of the enzyme was observed when the glucose concentration was less than 6.7 g·l^–1 and reached up to 4 IU·ml^–1 at the end of the fermentation. Offprint requests to: M. Raimbault     

Effect of paclobutrazol on wheat salt tolerance at pollination stage

The effects of paclobutrazol (PBZ) (0, 30, 60, and 90 ppm) and NaCl (0, 75, 150, and 225 mM) treatments on a salt-tolerant (Karchia-65) cultivar of wheat (Triticum aestivum L.) at the pollination stage were studied. Salt stress decreased plant height, the length and area of the flag leaf, fresh and dry weights of the shoot, roots, and flag leaf, and water content. On the background of salinity, PBZ treatment further suppressed plant height. Although plants growth was suppressed in PBZ-treated plants, PBZ treatment moderated the negative effect of salinity on some growth parameters. Under PBZ treatments, plants tissues accumulated more watersoluble carbohydrates and reducing sugars than control plants, with the exception of water-soluble carbohydrates in the roots. The Na⁺ content in roots significantly (p ≤ 0.05) increased at 150 and 225 mM NaCl, but PBZ treatment moderated the harmful effect of the highest levels of salinity. Salinity with or without PBZ treatment improved the K⁺, P, and N contents in plants. It is reasonably to suggest that the protection and increasing salt tolerance caused by PBZ was due to the mechanism nearly similar to the salt-tolerant cultivar physiological systems. These observations suggest that PBZ treatment has the potential to increase salt tolerance with a limiting damage caused by salt stress even in salt-tolerant plants. This text was submitted by the authors in English. Published in Russian in Fiziologiya Rastenii, 2009, Vol. 56, No. 2, pp. 278–284.     

Kinetic analysis of ethanol production by an acetate-resistant strain of recombinant Zymomonas mobilis

Zymomonas mobilis ZM4/Ac^R (pZB5), a mutant recombinant strain with increased acetate resistance, has been isolated following electroporation of Z. mobilis ZM4/Ac^R. This mutant strain showed enhanced kinetic characteristics in the presence of 12 g sodium acetate l^–1 at pH 5 in batch culture on 40 g glucose, 40 g xylose l^–1 medium when compared to ZM4 (pZB5). In continuous culture, there was evidence of increased maintenance energy requirements/uncoupling of metabolism for ZM4/Ac^R (pZB5) in the presence of sodium acetate; a result confirmed by analysis of the effect of acetate on other strains of Z. mobilis. Nomenclature m Cell maintenance energy coefficient (g g^–1 h^–1)Maximum overall specific growth rate (1 h^–1)Maximum specific ethanol production rate (g g^–1 h^–1)Maximum specific total sugar utilization rate (g g^–1 h^–1)Biomass yield per mole of ATP (g mole^–1 Ethanol yield on total sugars (g g^–1)Biomass yield on total sugars (g g^–1)True biomass yield on total sugars (g g^–1)     

Photosynthetic and leaf morphological characteristics in Leucaena leucocephala as affected by growth under different neutral shade levels

Morphological and physiological measurements on individual leaves of Leucaena leucocephala seedlings were used to study acclimation to neutral shading. The light-saturated photosynthetic rate (P_{n max}) ranged from 19.6 to 6.5 mol CO₂ m^–2 s^–1 as photosynthetic photon flux density (PPFD) during growth decreased from 27 to 1.6 mol m^–2 s^–1. Stomatal density varied from 144 mm^–2 in plants grown in high PPFD to 84 mm^–2 in plants grown in low PPFD. Average maximal stomatal conductance for H₂O was 1.1 in plants grown in high PPFD and 0.3 for plants grown in low PPFD. Plants grown in low PPFD had a greater total chlorophyll content than plants grown in high PPFD (7.2 vs 2.9 mg g^–1 on a unit fresh weight basis, and 4.3 vs 3.7 mg dm^–2 on a unit leaf area basis). Leaf area was largest when plants were grown under the intermediate PPFDs. Leaf density thickness was largest when plants were grown under the largest PPFDs. It is concluded that L. leucocephala shows extensive ability to acclimate to neutral shade, and could be considered a facultative shade plant.Abbreviations the initial slope of the photosynthesis vs PPFD curve - P_{n max} the light-saturated photosynthetic rate - PPFD photosynthetic photon flux density     

Fermentation of xylose and rice straw hydrolysate to ethanol byCandida shehatae NCL-3501

Candida shehatae NCL-3501 utilized glucose and xylose efficiently in batch cultures. The specific rate of ethanol production was higher with mixtures of glucose and xylose (0.64–0.83 g g^–1 cells d^–1) compared to that with individual sugars (0.38–0.58 g g^–1 cells d^–1). Although the optimum temperature for growth was 30°C, this strain grew and produced appreciable levels of ethanol at 45°C. A stable ethanol yield (0.40–0.43 g g^–1 substrate utilized) was obtained between 10 g L^–1 and 80 g L^–1 of initial xylose concentration. Conversion efficiency was further improved by immobilization of the cells in calcium alginate beads. Free or immobilized cells ofC. shehatae NCL-3501 efficiently utilized sugars present in rice straw hemicellulose hydrolysate, prepared by two different methods, within 48 h. Ethanol yields of 0.45 g g^–1 and 0.5 g g^–1 from autohydrolysate, and 0.37 g g^–1 from acid hydrolysate were produced by free and immobilized cells, respectively.     

Production of ajmalicine and ajmaline in hairy root cultures of Rauvolfia micrantha Hook f., a rare and endemic medicinal plant

Hairy roots of Rauvolfia micrantha were induced from hypocotyl explants of 2–3 weeks old aseptic seedlings using Agrobacterium rhizogenes ATCC 15834. Hairy roots grown in half-strength Murashige & Skoog (MS) medium with 0.2 mg indole 3-butyric acid l^–1 and 0.1 mg -naphthaleneacetic acid l^–1 produced more ajmaline (0.01 mg g^–1 dry wt) and ajmalicine (0.006 mg g^–1 dry wt) than roots grown in auxin-free medium. Ajmaline (0.003 mg g^–1 dry wt) and ajmalicine (0.0007 mg g^–1 dry wt) were also produced in normal root cultures. This is the first report of production of ajmaline and ajmalicine in hairy root cultures of Rauvolfia micrantha.     

Leaf non-structural carbohydrates regulated by plant functional groups and climate: Evidences from a tropical to cold-temperate forest transect

Non-structural carbohydrates (NSCs), e.g., glucose and starch, play important roles in metabolic processes of plants and represent important functional traits in plant's adaptation to external environment. To explore the variations in leaf NSCs among species and communities at a large scale and their influencing factors, we investigated the contents of leaf NSCs among 890 plant species in nine typical forests along the north–south transect of eastern China. The results showed that the contents of leaf soluble sugars, starch, and NSCs (sugars + starch) were highly variable among different plant species on the site scale, and their mean values for the 890 plant species were 45.7 mg g⁻¹, 47.5 mg g⁻¹, and 93.2 mg g⁻¹, respectively. All three metrics varied markedly across plant functional groups in the order of trees < shrubs < herbs. Weak latitudinal patterns of leaf soluble sugars, starch, and NSCs were observed from tropical to cold-temperate forests at the levels of species and plant functional groups. The contents of leaf soluble sugars, starch, and NSCs decreased with increasing temperature and precipitation which supports the growth limitation hypothesis at a large scale. In trees, leaf soluble sugars, starch, and NSCs increased with increasing photosynthetic active radiation (PAR); and were positively correlated with specific leaf area (SLA). The spatial patterns of leaf NSCs in forests along the north–south transect of eastern China and their relationships with temperature, precipitation, PAR, and SLA illustrate an important adaptation of plant communities to environmental changes at the continental scale.     

Photosynthesis and Leaf Nutrient Contents in Ochroma Pyramidale (Bombacaceae)

In Ochroma pyramidale (Cav. ex Lam.) Urb., photon-saturated photosynthetic capacity (P _Nmax) was 13 mol(CO₂) m^–2 s^–1. Average stomatal conductance (g _s) and water-use efficiency (WUE) were greater at high irradiance, about 260 mmol(H₂O) m^–2 s^–1 and 2.15 g(C) kg^–1(H₂O), respectively. In the dark, g _s values were about 30% of maximum g _s. Leaf nutrient contents on a leaf area basis were 131, 15, 36, 21, and 12 mmol m^–2 for N, P, K, Ca, and Mg, respectively. Ochroma also accumulated a greater amount of soluble saccharides than starch, 128 versus 90 g kg^–1 (DM). The availability of N and Mg, but not P, Ca, or K, may limit photosynthetic rates of Ochroma in this site.     

Enhanced colchicine production in root cultures of Gloriosa superba by direct and indirect precursors of the biosynthetic pathway

Excised root cultures of Gloriosa superba reached 7.5 g dry wt l^–1 and accumulated 240±40 g colchicine g^–1 cell dry wt after 4 weeks growth. While all precursors (except trans-cinnamic acid) enhanced colchicine content of root cultures without adversely affecting root growth, treatment with p-coumaric acid + tyramine (each at 20 mg l^–1) increased colchicine content to 1.9 mg g^–1 cell dry wt.