Albena Ivanova

Exogenous treatment with salicylic acid attenuates cadmium toxicity in pea seedlings

The present study investigated the possible mediatory role of salicylic acid (SA) in protecting plants from cadmium (Cd) toxicity. The exposure of pea plants to increasing Cd concentrations (0.5, 1.0, 2.0 and 5.0 microM) during early stages of their establishment, caused a gradual decrease in shoot and root fresh weight accumulation, the rate of CO2 fixation and the activity of ribulose-1,5-bisphosphate carboxylase (RuBPC, E.C. 4.1.1.39), the effect being most expressed at higher Cd concentrations. In vivo the excess of Cd-induced alterations in the redox cycling of oxygen-evolving centers and the assimilatory capacity of the pea leaves as revealed by changes in thermoluminescence emission after flash illumination. The levels of some important parameters associated with oxidative stress, namely lipid peroxidation, electrolyte leakage and proline production were increased. Seed pretreatment with SA alleviated the negative effect of Cd on growth, photosynthesis, carboxylation reactions, thermoluminescence characteristics and chlorophyll content, and led to decrease in oxidative injuries caused by Cd. The data suggest that the beneficial effect of SA during an earlier growth period could be related to avoidance of cumulative damage upon exposure to cadmium thus reducing the negative consequences of oxidative stress caused by heavy metal toxicity. In addition, the observed high endogenous levels of SA after treatment with Cd suggests that SA may act directly as an antioxidant to scavenge the reactive oxygen species and/or indirectly modulate redox balance through activation of antioxidant responses. Taken together these evidences could explain at some extend the protective role of SA on photochemical activity of chloroplast membranes and photosynthetic carboxylation reactions in Cd-stressed pea plants.

Volatile compounds from some Black Sea red algae and their chemotaxonomic application

Abstract Volatile compounds from the Black Sea red algae Bangia fuscopurpurea, Gelidium latifolium, Callithamnion granulatum, Ceramium elegans, Laurencia papillosa and Laurencia coronopus were obtained by distillation-extraction and analysed by GC/MS. Different groups of compounds were identified: hydrocarbons, alkylated benzenes, alcohols, phenols, aldehydes, ketones, acids, esters, terpenes, nitrogen- and halogen-containing compounds. The results are compared with some recent data for the composition of the volatile compounds from four previously investigated Black Sea red algae, which are at different evolutionary stages. On the basis of their qualitative and semi-quantitative composition some chemotaxonomic conclusions are proposed. The eventual functions of some of the volatile compounds are briefly discussed.

Effect Of Diesel Fuel Pollution On The Lipid Composition Of Some Wide-Spread Black Sea Algae And Invertebrates

Two green algae (Ulva rigida and Cladophora coelothrix), the mussel Mytilus galloprovincialis and the snail Rapana thomasiana from the Bulgarian Black Sea shore have been treated with diesel fuel (100 mg l-1) in an aquarium with sea-water for three days. The lipids and their fatty acid changes have been examined. Significant changes have been observed mainly in the polar lipids and in the saturation of the fatty acids. These changes appeared to be bigger in the evolutionary less advanced species from both groups of marine organisms D algae and invertebrates (Ulva rigida and Mytilus galloprovincialis respectively). The data obtained could be used for a biomonitoring of the pollution

Chemical composition of the sponge Chondrosia reniformis from the Canary Islands

The fatty acid composition of the lipids from Chondrosia reniformis (Nardo, 1847) was investigated and 57 acids were identified. One of them is new for nature and its structure was elucidated by GC/mass-spectrometry. This acid was identified as 8,10-dimethyl-16:0. The sterol composition was relatively simple and only 12 sterols were present. In the volatile fraction, 21 compounds were identified, mainly fatty acids, their esters and hydrocarbons, while in the n-butanol fraction we found mainly free fatty acids and free amino acids, together with significant amounts of sterols which probably are included in some polar complexes.

Role of Salicylic Acid in Alleviating Heavy Metal Stress

Both plant breeders and crop producers have an interest in finding crops capable of tolerating environmental changes with damage as little as possible. In order to develop such crops, the knowledge of plant defense mechanisms and regulatory processes is essential. The study presented in this chapter was performed to analyze the role of salicylic acid (SA) in regulation of plant growth and development, flowering, ion uptake, stomatal regulation and photosynthesis. The role of SA in development of plant resistance to different environmental stresses is described. Besides the physiological functions of SA, the general properties, biosynthesis and metabolism of this plant growth regulator are discussed. The present chapter focuses on the mechanisms of the beneficial effect of SA on maize plants exposed to toxic Cd concentrations.

Unusual lipid composition of a Bacillus sp. isolated from Lake Pomorie in Bulgaria.

The lipid composition of a Bacillus sp., isolated from Lake Pomorie in Bulgaria, was unusual and consisted of 26 different fatty acids between C12 and C26, with anteiso C15−C17 saturated fatty acids predominating. The furan fatty acid, 10,13-epoxy-11-methyloctadeca-10,12-dienoic acid, was also identified, a new finding for this genus. The hydrocarbons consisted of 30 different monounsaturated hydrocarbons, between C25 and C30, with the iso-iso, iso-anteiso, anteiso-anteiso, iso-normal, and anteiso-normal methyl branching for odd-numbered chains, and the iso-iso, iso-anteiso, iso-normal, and anteiso-normal methyl branching for even-numbered chains. The double bond positions in these hydrocarbons were determined by dimethyl disulfide derivatization followed by GC-MS, and the double-bond cis configuration was confirmed by infrared spectroscopy. Some previously unknown hydrocarbons in bacteria, such as (Z)-3,21-dimethyl-9-tricosene, (Z)-3,21-dimethyl-10-tricosene, (Z)-2,24-dimethyl-11-pentacosene, and (Z)-2,25-dimethyl-13-hexacosene were identified. Sterols were detected and were based on the sitosterol nucleus.

INFLUENCE OF FOLIAR FERTILIZATION AND GROWTH REGULATOR ON MILK THISTLE SEED YIELD AND QUALITY

The effects of foliar fertilization and a growth regulator 5-tert-butyl-N-m-tolylpyrazine-2-carboxamide (MD148/II) on the growth, seed yield, and silymarin content of milk thistle (Silybum marianum Gaertn.) plants were evaluated. The study was conducted over two years at an experimental field on a slightly acid-leached cinnamonic meadow soil. The MD148/II was applied in the beginning of milk thistle flowering stage. Foliar fertilizer was applied at different plant developmental stages with different proportions of nitrogen (N), phosphorus (P), and potassium (K). Treatments with foliar fertilizer and MD148/II resulted in improvement of plant biomass, number of plant lateral shoots, flowering rate, and seed yield and the content of some active substances in milk thistle seeds. A reduction of high molecular fatty acids was observed. The increase of seed yield was a result of the flower head setting enhancement. Therefore the combined treatment of foliar fertilizer and MD148/II was efficient in elicitation milk thistle production under field conditions.

Lipophylic compounds from Euphorbia peplis L.--a halophytic plant from the Bulgarian Black Sea coast.

Abstract The chemical composition of the lipophylic fraction from the halophytic plant Euphorbia peplis L. was investigated. Compared to other terrestrial higher plants an increase of triacylglycerols and especially of glycolipids was observed. The main phospholipid was phosphatidyl choline, followed by almost equal concentrations of phosphatidyl ethanolamine and phosphatidyl glycerol. A relatively high concentration of phosphatidic acids (6.5% of the total phospholipids) was found. The main sterol appeared to be sitosterol and significant amounts of tetracyclic triterpene alcohols were found. The composition of the volatile compounds is relatively simple and only one chlorinated compound, identified as 2,2-diethoxy-1-chloroethane, was found. There was a strong toxicity of the total lipophylic extract towards Artemia salina.

Chemical composition of the halophyte plant Stachys maritima Gouan from the Bulgarian Black Sea coast

Four groups of metabolites from the halophyte plant Stachys maritima Gouan, family Lamiaceae, were investigated: lipids, sterols, volatiles and polar compounds. Most of the metabolites have been previously reported to possess biological activity. Two of the main substances in the volatile fraction – phenidone and naphthalene, unusual for plants – were products of environmental contamination. This is a typical example of how marine pollutants could transfer and threaten terrestrial organisms via the trophic chain. The n-butanol extract possessed a relatively high antibacterial activity against S. aureus and Candida albicans, but was not active against Escherichia coli.

The Effect of Mineral Nutrition on Photostnthetic Activity and Saponin Content of Puncture Vine (Tribulus Terrestris L.)

Puncture vine (Tribulus terrestris L., Zygophyllaceae) is an annual prostrate medicinal plant that is widely used for treatment of sexual deficiency, as an affrodiziak. Steriodal saponins and rutin are among the basic compounds responsible for the biological activities of T. terrestris extracts. Efficiency of mineral nutrition (soil or foliar supply of nutrients ) on the growth, dry matter and saponin content of the above ground biomass of Bulgarian variety puncture vine grown in soil as pot experiment in green house have been studied. Soil fertilization rate of 100 mgN/kg or 90 P/kg of dry soil, oppositely to the results obtained from the foliar fed plants (0.3% solution of liquid fertilizer AgroleafR (Scotts Co, U.S.A.) with formulation N12P52K5, increased shoot total N and P without significant change of dry matter. Changes of total reducing sugars, amino acids, phenolics and flavonoids and activity of photosynthetic apparatus (thermoluminescence emission) were found to relate to the variation of individual saponin contents analysed by HPLC technique. Soil fertilized plant in contrast to the foliar fed plants showed more furostanol saponins (protodioscin, prototribestan and dioscin) than control but contained less of flavonoid glycoside rutin.