Seasonal Variations in Carnosic Acid Content of Rosemary Correlates with Anthocyanins and Soluble Sugars

Seasonal variations may influence the quality and quantity of biologically active ingredients in medicinal plants. Rosemary (Rosmarinus officinalis L.) a member of the Lamiaceae family, contains valuable antioxidant, anticancer and antibacterial substances, including Carnosic acid (CA). Here, the fluctuations of important active compounds present in rosemary leaf extracts collected in Golestan, Iran were studied during the year of 2012-2013. Plant phenolics, flavonoids, ascorbates, anthocyanins and soluble sugars were analyzed spectrophotometrically, while CA content was measured by High Performance Liquid Chromatography (HPLC). The highest amounts of total flavonoids occurred in autumn; while CA, phenolics, ascorbic acids and soluble sugars were greatest in winter, probably due to regional high precipitation and subtle winters. Most of the above indicated active compounds were low in early summer. Furthermore, total anthocyanins and soluble sugars showed significant positive correlations with CA over the year. These data suggest that rosemary extracts from the collected leaves in winter contain greater amounts of biologically active compounds; and can be used for standardization of plant materials harvested throughout a year

The Role of Leaf Anatomy and Morphology in Determining Ozone Susceptibility in Cut-leaf Coneflower

Cutleaf coneflower (Rudbeckia laciniata var. digitata) is an ozone sensitive native wildflower growing within Great Smoky Mountains National Park (GRSM) where ozone pollution is often a problem. Individual coneflowers exhibit substantial variation in ozone sensitivity, yet the causes for this are not yet known. The purpose of my study was to evaluate whether differences in leaf anatomy and morphology between sensitive and tolerant individuals of coneflower were responsible for this variation in ozone susceptibility. I hypothesized that sensitive individuals would have thinner leaf and mesophyll layers, greater internal airspace, greater exposed cell surface, and thinner cell walls. Leaf samples were collected in June, July and August of 2004 from both sensitive and tolerant individuals for analysis. Micrographic measurements were made on thin prepared sections using light microscopy and included cuticle thickness, leaf and mesophyll thickness, internal airspace, exposed cell surface, cell area, live and dead cell number and cell wall thickness. There were few effects on any parameters related to sensitivity and the majority of differences found were related to season and habitat effects. Leaf anatomy and morphology did not differ between sensitive and tolerant plants, and therefore, these attributes do not appear to be the cause of sensitivity differences

Effects of elevated ozone on physiological, anatomical and ultrastructural characteristics of four common urban tree species in China

Fast urbanization has led to ozone (O3) being the main pollutant in summer in most of China. To assess future ground-level O3 effects on the service of urban greening species and clarify the underlying mechanism of O3 damage, four common urban greening species, Ailanthus altissima (AA), Fraxinus chinensis(FC), Platanus orientalis (PO) and Robinia pseudoacacia (RP) were exposed to non-filtered air (NF) and to elevated O3 (E-O3) in open-top chambers. E-O3 induced visible injury in all species as well as microscopic alterations such as collapse of the palisade parenchyma cells, callose accumulation, or chloroplast and mitochondrial accelerated senescence. E-O3 significantly reduced light-saturated CO2 assimilation (Asat),the maximum activity of Rubisco (Vcmax), the maximum electron transport rate (Jmax), and fluorescence parameters such as the quantum yield of noncyclic electron transport (�PSII), and the quenching of photochemical efficiency of PSII (qP). It also increased total antioxidant capacity, phenolics and ascorbate contents. No significant interaction between O3and species was found in photosynthetic performance and antioxidant systems, suggesting that the four species selected were sensitive to O3. Of all four species,AA was the most sensitive species due to a combination of earlier injury onset, anatomical features, lower antioxidant responses and higher stomatal conductance. The sensitivity of tree species to O3 is a factor to be considered for urban greening. Ozone may affect important urban forest ecosystem services by reducing CO2 assimilationThis study has been funded by the Hundred Talents Program, Chinese Academy of Sciences and State Key Laboratory of Urban and Regional Ecology. Collaboration between RCEES and Fundacion CEAM has been possible thanks to project AMIS (Fate and Impact of Atmospheric Pollutants, PIRSES-GA-2011-295132), and by the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists (grant number: 2013T2Z0009). VC also acknowledges the support of PROMETEOII/2014/038 project (Generalitat Valenciana, G.V.), and FGB and JRA that of PROMETEOII2013/021 (G.V.), and CGL2012-40058-C02-01/02 (MINECO). We thank Mr. Yulong Zhang for the experimental management.Gao, F.; Calatayud Lorente, V.; García-Breijo, F.; Reig Armiñana, J.; Feng, Z. (2016). Effects of elevated ozone on physiological, anatomical and ultrastructural characteristics of four common urban tree species in China. Ecological Indicators. 67:367-379. https://doi.org/10.1016/j.ecolind.2016.03.012S3673796

Wheat yield responses to stomatal uptake of ozone: peak vs rising background ozone conditions

Recent decades have seen a changing temporal profile of ground-level ozone (O3) in Europe. While peaks in O3 concentrations during summer months have been declining in amplitude, the background concentration has gradually increased as a result of the hemispheric transport of O3 precursors from other world regions. Ground-level O3 is known to adversely affect O3-sensitive vegetation, including reducing the yield of O3-sensitive crops such as common wheat (Triticum aestivum L.). The reduction in wheat yield has been shown to be linearly related to the phytotoxic O3 dose above a flux threshold of Y (PODY) accumulated over a specific period. In the current study, we tested whether the flux-effect relationships for wheat yield and 1,000-grain weight were affected by the temporal profile of O3 exposure. A modern wheat cultivar (Skyfall) was exposed to eight different realistic O3 profiles repeated weekly: four profiles with increasing background O3 concentrations (ca. 30–60 ppb) including small peaks and four profiles with increasing O3 peak concentrations (ca. 35–110 ppb). Both wheat yield and 1,000-grain weight declined linearly with increasing PODY. The slope of the flux-effect relationships was not affected significantly by the profile of O3 exposure. Hence, flux-effect relationships developed for wheat based on exposure to enhanced peak O3 concentrations are also valid for the changing European O3 profile with higher background and lower peak concentrations. The current study also shows that the modern wheat cultivar Skyfall is more sensitive to O3 than European wheat varieties tested for O3 sensitivity in the 1980s and 1990s

A site-specific analysis of the implications of a changing ozone profile and climate for stomatal ozone fluxes in Europe

In this study, we used eight sites from across Europe to investigate the implications of a future climate (2 °C warmer and 20% drier) and a changing ozone profile (increased background concentrations and reduced peaks) on stomatal ozone fluxes of three widely occurring plant species. A changing ozone profile with small increases in background ozone concentrations over the course of a growing season could have significant impacts on the annual accumulated stomatal ozone uptake, even if peak concentrations of ozone are reduced. Predicted increases in stomatal ozone uptake showed a strong relationship with latitude and were larger at sites from northern and mid-Europe than those from southern Europe. At the sites from central and northern regions of Europe, including the UK and Sweden, climatic conditions were highly conducive to stomatal ozone uptake by vegetation during the summer months and therefore an increase in daily mean ozone concentration of 3–16% during this time of year (from increased background concentrations, reduced peaks) would have a large impact on stomatal ozone uptake. In contrast, during spring and autumn, the climatic conditions can limit ozone uptake for many species. Although small increases in ozone concentration during these seasons could cause a modest increase in ozone uptake, for those species that are active at low temperatures, a 2 °C increase in temperature would increase stomatal ozone uptake even in the absence of further increases in ozone concentration. Predicted changes in climate could alter ozone uptake even with no change in ozone profile. For some southern regions of Europe, where temperatures are close to or above optimum for stomatal opening, an increase in temperature of 2 °C could limit stomatal ozone uptake by enhancing stomatal closure during the summer months, whereas during the spring, when many plants are actively growing, a small increase in temperature would increase stomatal ozone uptake