Dried leaves of Rosmarinus officinalis as a treatment for streptococcosis in tilapia.

Dietary application of dried Rosmarinus officinalis (rosemary) leaves as a treatment for streptococcal infection was studied in tilapia, Oreochromis sp. Feeding with dried rosemary leaves significantly reduced mortality following infection with Streptococcus iniae: 44% mortality in the group fed 8% rosemary, similar to oxytetracycline treatment (43% mortality), and significantly lower than the control (65%). Dietary administration of 16% rosemary significantly reduced mortality because of Streptococcus agalactiae infection in 44 g fish (62% and 76% in 16% rosemary and control, respectively), but not in a similar experiment conducted with 5.5 g fish. The antibacterial effect of rosemary on S. iniae was studied. Activity of rosemary cultivar Israel was reduced during the winter, but there was no significant change in cultivars Oranit and Star. Storage of powdered rosemary leaves at 50 degrees C resulted in fourfold and eightfold higher MIC(24 h) values after 3 and 4.5 months, respectively. Storage at -20 degrees C, 4 degrees C and 25 degrees C and autoclaving (120 degrees C) each resulted in a twofold increase in MIC(24 h). Repeated exposures of S. iniae to rosemary did not affect minimal inhibitory concentration, suggesting no development of resistance to rosemary.

Inheritance of Resistance to Fusarium Wilt in Sweet Basil.

Fusarium wilt, caused by Fusarium oxysporum f. sp. bacilici, is a severe disease of sweet basil (Ocimum basilicum L.) and has become acute mainly due to the intensive monoculture in green-houses and, recently, to prohibition of methyl bromide application. In a previous work, we selected a resistant cultivar, Nufar, to address this problem. The mode of inheritance of resistance to F. oxysporum f. sp. bacilici in sweet basil was examined in progenies derived from crosses of the homogeneous resistant cv. Nufar and the susceptible homogenous cv. Chen. Artificial inoculation of seedlings with a high concentration of a microconidial suspension of a virulent isolate of F. oxysporum f. sp. bacilici revealed no difference between reciprocal backcrosses. The nuclear resistance analysis and dominant characteristics of the resistance of backcross progenies of different parental lines and the segregation for resistance in F2 combinations fitted the expected Mendelian ratio for a single dominant gene with two alleles that confer resistance to Fusarium wilt in basil. These results indicate the usefulness of utilizing this resistance to F. oxysporum f.sp. bacilici in the production of new hybrids and cultivars of basil.

Biotransformation of constituents of essential oils by germinating wheat seed.

Wheat seeds, when exposed to essential oils, are able to metabolise certain monoterpenes. The actual amounts of the compounds and their derivatives in the endosperm and embryo of wheat seeds, after exposure to the monoterpenes were determined. Neral and geranial, which are the constituents of citral, are reduced and oxidised to the corresponding alcohols and acids. Similarly citronellal, pulegone and carvacrol are converted partly to the corresponding reduction and oxidation products. The aromatic compound vanillin is partly reduced to vanillyl alcohol or oxidised to vanillic acid. In all cases it seems that part of the compounds applied are degraded, as indicated by the inability to account for all the compounds, which were supplied to the germinated seeds. In most cases the derivatives of the essential oil applied were less toxic than the parent compound. The possible role of non-specific enzymes by which the compounds are oxidised or reduced is discussed.

Changes in essential oil during enzyme-assisted ensiling of lemongrass (Cymbopogon citratus Stapf.) and lemon eucalyptus (Eucalyptus citriodora Hook).

Changes in essential oil during ensiling of lemongrass and lemon eucalyptus were studied. Wilted lemongrass and eucalyptus leaves were ensiled in 0.25-L anaerobic jars. Samples consisted of a control (no additives) and a treated sample (0.5% glucose and lactic acid bacteria and 1% cellulase plus 1% hemicellulase plus pectinase). Three jars per treatment were sampled on days 2, 6, 10, and 36 for analysis of essential oil. Essential oil was obtained by extraction and by hydrodistillation. Extraction efficacy of essential oil from the lemongrass was improved by the enzyme treatment, but it was much lower than the amount obtained by distillation. The major components of the essential oil were neral and geranial. In the eucalyptus, total essential oils obtained by distillation decreased during ensiling, and the amount was similar to the amount obtained by extraction. Citronellal, which was the major component of the essential oil in the fresh eucalyptus leaves, decreased, whereas isopulegol and 3,8-terpinolhydrate increased during ensiling.

Dynamics of yield components and essential oil production in a commercial hybrid sage (Salvia officinalis x Salvia fruticosa cv. Newe Ya'ar no. 4).

The fresh yields, the essential oil content, and the quality of a sage hybrid (Salvia officinalis x Salvia fruticosa, cv. Newe Ya'ar No. 4, Lamiaceae) as affected by development and harvest time were determined. Marked increases in plant height and in the number of nodes developed per plant together with a modest increase in leaf size were accompanied by dramatic increases (more than 20-fold) in the fresh yields throughout a 50-day growth period. No major changes in the essential oil content per fresh weight and its composition were detected throughout the growth period. In contrast, the compositions of the essential oils obtained from stems, as compared to leaves and leaf-primordia, had marked differences. Developmentally controlled changes in the extractives from individual leaf pairs from the same plant were also noted. In upper young leaves, the oxygenated diterpene manool and the sesquiterpene hydrocarbons alpha-humulene and beta-caryophyllene constituted up to 20%, 8%, and 4% of the total extractives, respectively. In older leaves, the abundance of these components steadily dropped to roughly half their levels in young leaves. Conversely, the proportions of the monoterpenes, particularly the ketones camphor and alpha-thujone, steadily increased with leaf position. Minor changes in the levels of other extractives were also recorded. These studies imply independent regulatory patterns for di-, sesqui-, and monoterpenes in this sage hybrid, and suggest possible agrotechnical means to obtain preferred chemical compositions of its essential oil.

Cadmium accumulation in Allium schoenoprasum L. grown in an aqueous medium.

The ability of Allium schoenoprasum L. (chives) to accumulate and tolerate cadmium in aqueous Hoagland medium at 50microM and 250microM was tested under continuous growth or several successive harvests of shoots. After 28 days of continuous growth, chives accumulated the metal up to 0.2% and 0.5% of its dry weight, when grown in 50microM and 250microM, respectively. In experiments that the leaves were successively harvested every 16 days, there were no obvious stress symptoms after six harvests during a period of 96 days at 50microM Cd. At 250microM, after 64 days and four harvests, inhibition of growth occurred. In each treatment, a total of 1.2g kg(-1) DW and 2.4g kg(-1) DW was accumulated in the leaves, respectively. Total SH compounds concentration in leaf was found significantly higher by 3 and 7.4 times in plants treated with Cd at 50microM and 250microM in comparison to the control, respectively, while no difference in the concentration of glutathione (GSH+GSSG) was found. Thus, it is assumed that sulphur-containing compounds, yet unknown, are involved in defensive mechanisms against heavy metals in chives. The results presented, point to chives phytoremediation potential, but also on the potential risk in accumulation of heavy metals in a commonly edible plant.

The relative effect of citral on mitotic microtubules in wheat roots and BY2 cells.

The plant volatile monoterpene citral is a highly active compound with suggested allelopathic traits. Seed germination and seedling development are inhibited in the presence of citral, and it disrupts microtubules in both plant and animal cells in interphase. We addressed the following additional questions: can citral interfere with cell division; what is the relative effect of citral on mitotic microtubules compared to interphase cortical microtubules; what is its effect on newly formed cell plates; and how does it affect the association of microtubules with γ-tubulin? In wheat seedlings, citral led to inhibition of root elongation, curvature of newly formed cell walls and deformation of microtubule arrays. Citral's effect on microtubules was both dose- and time-dependent, with mitotic microtubules appearing to be more sensitive to citral than cortical microtubules. Association of γ-tubulin with microtubules was more sensitive to citral than were the microtubules themselves. To reveal the role of disrupted mitotic microtubules in dictating aberrations in cell plates in the presence of citral, we used tobacco BY2 cells expressing GFP-Tua6. Citral disrupted mitotic microtubules, inhibited the cell cycle and increased the frequency of asymmetric cell plates in these cells. The time scale of citral's effect in BY2 cells suggested a direct influence on cell plates during their formation. Taken together, we suggest that at lower concentrations, citral interferes with cell division by disrupting mitotic microtubules and cell plates, and at higher concentrations it inhibits cell elongation by disrupting cortical microtubules.

Growth management of vetiver (Vetiveria zizanioides) under Mediterranean conditions.

In spite of the advantages of Vetiver grass in light of environmental aspects, this plant is not used in the Mediterranean region. The objectives of the present study were: (i) to elucidate growth parameters and establishment of Vetiver under Mediterranean conditions suitable for its various environmental applications; and (ii) to develop management practices for growing vetiver under Mediterranean conditions. In greenhouse experiments conducted under controlled conditions it was found that, in general, increasing the minimum/maximum temperatures to 21-29 degrees C significantly increased plant height. In the Mediterranean region, this range of air temperatures is obtained mainly during the summer, from June to September. For air temperatures up to 15-23 degrees C the effect of day length on plant height was insignificant, whereas in air temperature >15-23 degrees C, the plant heights under long day conditions were significantly higher than under short day. The number of sprouts per plant increased exponentially with increasing air temperature, and was not significantly affected by the day length at any air temperature range. In open fields, the heights of irrigated vetiver plants were significantly higher than those of rain-fed plants. It was concluded that, once they were established, vetiver plants could survive the dry summer of the Mediterranean region under rain-fed conditions, but they would be shorter than under irrigation. Cutting or burning of the plant foliage during the spring did not improve the survival of vetiver during the dry summer. In order to obtain fast growth of vetiver and to increase the possibility of its using the rainwater, the plants should be planted in the winter, during February and March. However, under this regime, the vetiver plant cannot be used as a soil stabilizer during the first winter, because the plant is still small. In contrast, under irrigation it is advantageous to plant vetiver at the beginning of the summer; the plant then has sufficient time to grow and develop before the beginning of the winter, so that its effect as a soil stabilizer in the following wet winter could be maximal. It was found that vetiver could grow in a wide range of substrates, such as: sandy soil, loamy sand, clay soil, crushed limestone, sandy clay loam, and tuff/peat mixture.

Soil microvariations as a source of variability in the wild: the case of secondary metabolism in Origanum dayi post.

The volatile components of Origanum dayi Post were analyzed in 10 wild populations grown in a limited area. ANOVA tests showed no significant differences among the compositions of plants that grew in different locations, which suggests that differences in composition are of genetic origin and do not spring from environmental variation. However, the use of new statistical methods (such as use of the correlation coefficient, r, as a parametric value) revealed that, despite their reduced range of variation, most of the 22 soil properties (SPs) measured correlated with the composition of the volatile components. This analysis also indicated that the main volatile components were modified in parallel in response to SP variations. It is concluded that variations in soil properties affected the composition of volatile components in O. dayi, and that the main influencing factors were soil microelement contents and texture. This study highlights the need for highly sensitive statistical tools to determine the actual influence of environmental factors in natural environments, especially when their range of variation is small.

Biosynthesis of estragole and methyl-eugenol in sweet basil (Ocimum basilicum L). Developmental and chemotypic association of allylphenol O-methyltransferase activities.

Sweet basil (Ocimum basilicum L., Lamiaceae) is a common herb, used for culinary and medicinal purposes. The essential oils of different sweet basil chemotypes contain various proportions of the allyl phenol derivatives estragole (methyl chavicol), eugenol, and methyl eugenol, as well as the monoterpene alcohol linalool. To monitor the developmental regulation of estragole biosynthesis in sweet basil, an enzymatic assay for S-adenosyl-L-methionine (SAM):chavicol O-methyltransferase activity was developed. Young leaves display high levels of chavicol O-methyltransferase activity, but the activity was negligible in older leaves, indicating that the O-methylation of chavicol primarily occurs early during leaf development. The O-methyltransferase activities detected in different sweet basil genotypes differed in their substrate specificities towards the methyl acceptor substrate. In the high-estragole-containing chemotype R3, the O-methyltransferase activity was highly specific for chavicol, while eugenol was virtually not O-methylated. In contrast, chemotype 147/97, that contains equal levels of estragole and methyl eugenol, displayed O-methyltransferase activities that accepted both chavicol and eugenol as substrates, generating estragole and methyl eugenol, respectively. Chemotype SW that contains high levels of eugenol, but lacks both estragole and methyl eugenol, had apparently no allylphenol dependent O-methyltransferase activities. These results indicate the presence of at least two types of allylphenol-specific O-methyltransferase activities in sweet basil chemotypes, one highly specific for chavicol; and a different one that can accept eugenol as a substrate. The relative availability and substrate specificities of these O-methyltransferase activities biochemically rationalizes the variation in the composition of the essential oils of these chemotypes.