Higher Levels Of Chlorophyll Research Articles

An alternative explanation for cyanobacterial scum formation and persistence by oxygenic photosynthesis

The cause of persistent cyanobacteria scum formation in lakes is an unresolved subject. Scum refers to the event in which cyanobacteria are at the water surface of a lake. Factors like low turbulence levels, long day-light, high water temperatures and the buoyant capacity of cyanobacterial cells play a role in the occurrence of scums. However, they do not explain why scums are observed at periods during the day when according to theory they should have disappeared into the deeper water layers. In this study, we present an alternative explanation. The hypothesis we present here is that irreversible buoyancy of cyanobacteria colonies is created by the growth of gas bubbles on or within the mucilage of the colonies. These bubbles grow under oxygen super-saturated conditions. At low wind speed and high chlorophyll levels, the dissolved oxygen (DO) produced during photosynthesis by cyanobacteria, cannot escape sufficiently fast to the atmosphere hence a DO supersaturated condition arises in the water. At this stage, growth of oxygen bubbles may occur inside or attached to the mucilage. We present results of compression experiments to support our hypothesis. In a chamber, the pressure on lake water containing a natural cyanobacteria population is increased. At 3×105 and 4×105Pa the cyanobacteria colonies were not able to float anymore and sank. This pressure is lower than the 106Pa needed to collapse all gas vacuoles inside the cyanobacteria cells (Walsby, 1994). The observed change from floating to sinking colonies due to increased water pressure suggests that gas bubbles were present inside the colonies. In lakes, these gas bubbles may lead to permanent buoyancy, i.e. a persistent scum.

Bioassimilable sulphur provides effective control of Oidium neolycopersici in tomato, enhancing the plant immune system.

Developments of alternatives to the use of chemical pesticides to control pests are focused on the induction of natural plant defences. The study of new compounds based on liquid bioassimilable sulphur and its effect as an inductor of the immune system of plants would provide an alternative option to farmers to enhance plant resistance against pathogen attacks such as powdery mildew. In order to elucidate the efficacy of this compound in tomato against powdery mildew, we tested several treatments: curative foliar, preventive foliar, preventive in soil drench and combining preventive in soil drench and curative foliar. In all cases, treated plants showed lower infection development, better physiological parameters and a higher level of chlorophyll. We also observed better performance in parameters involved in plant resistance such as antioxidant response, callose deposition and hormonal levels. The results indicate that preventive and curative treatments can be highly effective for the prevention and control of powdery mildew in tomato plants. Foliar treatments are able to stop the pathogen development when they are applied as curative. Soil drench treatments induce immune response mechanisms of plants, increasing significantly callose deposition and promoting plant development. © 2016 Society of Chemical Industry.

Using evolutionary multivariate adaptive regression splines approach to evaluate the eutrophication in the Pozón de la Dolores lake (Northern Spain)

Eutrophication is a water enrichment in nutrients (mainly phosphorus) that generally leads to symptomatic changes when the productions of algae and other aquatic vegetations are increased, and deterioration of water quality and all its uses in general. In this sense, eutrophication has caused a variety of impacts, such as high levels of Chlorophyll a (Chl-a). Consequently, anticipate its presence is a matter of importance to prevent future risks. The aim of this study was to obtain a predictive model able to perform an early detection of the eutrophication in water bodies such as lakes. This study presents a novel hybrid algorithm, based on multivariate adaptive regression splines (MARS) approach in combination with the artificial bee colony (ABC) technique, for predicting the eutrophication from biological and physical-chemical input parameters determined experimentally through sampling and subsequent analysis in a certificate laboratory. This optimization technique involves hyperparameter setting in the MARS training procedure, which significantly influences the regression accuracy. The results of the present study are two-fold. In the first place, the significance of each biological and physical-chemical variables on the eutrophication is presented through the model. Secondly, a model for forecasting eutrophication is obtained with success. Indeed, regression with optimal hyperparameters was performed and coefficients of determination equal to 0.85 for the Total phosphorus estimation and 0.84 for the Chlorophyll concentration were obtained when this hybrid ABC–MARS–based model was applied to the experimental dataset, respectively. The agreement between experimental data and the model confirmed the good performance of the latter. Finally, conclusions of this innovative research work are exposed.

Movilización y utilización de los sustratos energéticos de <i>Arca zebra</i> (Bivalvia: Arcidae) en relación con el ambiente

El análisis de los componentes bioquímicos en especies marinas para el consumo humano tiene una gran importancia, ya que permite conocer las propiedades alimenticias y energéticas del organismo. En el presente estudio, se evaluó el perfil bioquímico en tejidos de Arca zebra en relación con los factores ambientales, con la finalidad de ser utilizado como indicador de la dinámica reproductiva y de los periodos de engorde de este importante recurso pesquero. Se analizaron 20 organismos/mes, entre julio de 2010-julio de 2011. A cada organismo se le determinó el largo total (LT) y se separaron los tejidos, los cuales se llevaron hasta peso constante para realizarles los análisis bioquímicos mediante espectrofotometría. Se establecieron diferencias mensuales en la LT, con un promedio anual de 69.61 mm, manteniéndose por encima de la talla comercial. Los carbohidratos y las proteínas mostraron diferencias entre meses, con valores máximos en marzo y julio de 2011, siendo el músculo quien registró el mayor contenido de ambos sustratos energéticos, asociados a los altos niveles de clorofila a. Se observó una relación inversa entre los carbohidratos y las proteínas en los tres tejidos con respecto a la masa gonadal, sugiriendo una posible transferencia durante el proceso reproductivo de A. zebra. En las gónadas se registró el mayor contenido de lípidos, sin variación mensual, debido a la sincronía reproductiva de la especie. A. zebra muestra su mejor condición nutricional durante los periodos comprendidos entre septiembre-diciembre y marzo-junio, en estos meses se recomienda su comercialización e ingesta.

A Putative Chloroplast Thylakoid Metalloprotease VIRESCENT3 Regulates Chloroplast Development in Arabidopsis thaliana

The chloroplast is the site of photosynthesis and many other essential plant metabolic processes, and chloroplast development is an integral part of plant growth and development. Mutants defective in chloroplast development can display various color phenotypes including the intriguing virescence phenotype, which shows yellow/white coloration at the leaf base and greening toward the leaf tip. Through large scale genetic screens, we identified a series of new virescent mutants including virescent3-1 (vir3-1), vir4-1, and vir5-1 in Arabidopsis thaliana. We showed that VIR3 encodes a putative chloroplast metalloprotease by map-based cloning. Through site-directed mutagenesis, we showed that the conserved histidine 235 residue in the zinc binding motif HEAGH of VIR3 is indispensable for VIR3 accumulation in the chloroplast. The chloroplast localization of VIR3 was confirmed by the transient expression of VIR3-GFP in leaf protoplasts. Furthermore, taking advantage of transgenic lines expressing VIR3-FLAG, we demonstrated that VIR3 is an intrinsic thylakoid membrane protein that mainly resides in the stromal lamellae. Moreover, topology analysis using transgenic lines expressing a dual epitope-tagged VIR3 indicated that both the N and C termini of VIR3 are located in the stroma, and the catalytic domain of VIR3 is probably facing the stroma. Blue native gel analysis indicated that VIR3 is likely present as a monomer or part of a small complex in the thylakoid membrane. This work not only implicates VIR3 as a new factor involved in early chloroplast development but also provides more insight into the roles of chloroplast proteases in chloroplast biogenesis.

Bio-optical characterization and light availability parameterization in Uummannaq Fjord and Vaigat–Disko Bay (West Greenland)

Abstract. This study investigated the bio-optical conditions of Uummannaq Fjord and Vaigat–Disko Bay, two neighboring, semi-enclosed coastal systems in West Greenland. Though close to each other, the systems differ in their hydrographic structure influencing the bio-optical conditions and, subsequently, the biological activities. Both systems showed high inorganic suspended particulate matter (SPMi) concentrations near river runoff or meltwater influxes (max. of 15.28 mg L−1 at the surface) and low colored dissolved organic matter (aCDOM@350nm, < 1.50 m−1) abundance throughout the systems. High chlorophyll levels (as an indicator of phytoplankton biomass) were measured in the Vaigat (max. of 11.44 µg L−1), which represents the outflow arm of Disko Bay. Light penetration depth as indicated by the 1 % depth of photosynthetically available radiation (PAR) was dominated by chlorophyll and SPMi alike, ranging from 12.2 to 41.2 m. Based on these characteristics, an effective two-component parameterization for the diffuse attenuation coefficient kPAR was developed in order to model light penetration depth as a relevant factor for bio-optical studies in Arctic environments under glacial meltwater influence.

Habitat suitability of the Atlantic bluefin tuna by size class: An ecological niche approach

An ecological niche modelling (ENM) approach was used to predict the potential feeding and spawning habitats of small (5–25kg, only feeding) and large (>25kg) Atlantic bluefin tuna (ABFT), Thunnus thynnus, in the Mediterranean Sea, the North Atlantic and the Gulf of Mexico. The ENM was built bridging knowledge on ecological traits of ABFT (e.g. temperature tolerance, mobility, feeding and spawning strategy) with patterns of selected environmental variables (chlorophyll-a fronts and concentration, sea surface current and temperature, sea surface height anomaly) that were identified using an extensive set of precisely geo-located presence data. The results highlight a wider temperature tolerance for larger fish allowing them to feed in the northern – high chlorophyll levels – latitudes up to the Norwegian Sea in the eastern Atlantic and to the Gulf of Saint Lawrence in the western basin. Permanent suitable feeding habitat for small ABFT was predicted to be mostly located in temperate latitudes in the North Atlantic and in the Mediterranean Sea, as well as in subtropical waters off north-west Africa, while summer potential habitat in the Gulf of Mexico was found to be unsuitable for both small and large ABFTs. Potential spawning grounds were found to occur in the Gulf of Mexico from March–April in the south-east to April–May in the north, while favourable conditions evolve in the Mediterranean Sea from mid-May in the eastern to mid-July in the western basin. Other secondary potential spawning grounds not supported by observations were predicted in the Azores area and off Morocco to Senegal during July and August when extrapolating the model settings from the Gulf of Mexico into the North Atlantic. The presence of large ABFT off Florida and the Bahamas in spring was not explained by the model as is, however the environmental variables other than the sea surface height anomaly appeared to be favourable for spawning in part of this area. Defining key spatial and temporal habitats should further help in building spatially-explicit stock assessment models, thus improving the spatial management of bluefin tuna fisheries.

The ERF transcription factor EPI1 is a negative regulator of dark-induced and jasmonate-stimulated senescence in Arabidopsis.

Identification of the factors involved in the regulation of senescence and the analysis of their function are important for both a biological understanding of the senescence mechanism and the improvement of agricultural productivity. In this study, we identified an ERF gene termed "ERF gene conferring Postharvest longevity Improvement 1" (EPI1) as a possible regulator of senescence in Arabidopsis. We found that EPI1 possesses transcriptional repression activity and that the transgenic plants overexpressing EPI1 and expressing its chimeric repressor, EPI1-SRDX, commonly suppressed the darkness-induced senescence in their excised aerial parts. These transgenic plants additionally maintained a high level of chlorophyll, even after the methyl jasmonate (MeJA) treatment, which stimulated senescence in the dark. In addition, we found that senescence-induced and -reduced genes are down- and upregulated, respectively, in the MeJA-treated transgenic plants under darkness. Our results suggest that EPI1 functions as a negative regulator of the dark-induced and JA-stimulated senescence.

The Effect of 1-Methylcyclopropene on Postharvest Life of Sessile Joyweed (Alternanthera Sessilis)

Sessile Joyweed (Alteranthera sessilis) which is commonly known as Mukunuvenna in Sri Lanka, is the most widely produced and most popular of nine leafy vegetables cultivated and sold on a commercial scale in Sri Lanka. This is primarily consumed locally, while only a small quantity is exported. However, the shelf life of Mukunuvenna is as low about 3-4 days due to leaf yellowing and wilting. Consumers prefer green and turgid leafy vegetables and thus the loss is considerably high after wilting and yellowing. Ethylene is a critical problem in leaf senescence. Minute concentrations such as 1μL/L ethylene can affect leaf yellowing significantly. Thus, an ethylene blocker, 1-Methylcyclopropene (1-MCP), which is now commonly being used in the fruit industry, can be considered as an effective solution for extending the postharvest life of A. sessilis. It is not toxic and environmentally friendly thus safe with edible produce. The present study was done, with the objective of investigating effects of 1-MCP on postharvest life and sensory qualities. Two experiments were conducted for several dosages (concentration × time) to investigate the shelf-life performances and processed A. sessilis samples were used to check sensory qualities such as taste, smell, texture and colour.Samples treated with 1-MCP showed high levels of chlorophyll, lower yellowing and higher overall quality. Postharvest life of treated samples increased by 1 full-day (25% increase) under the room temperature. 1-MCP, 5ppm for 8 hour duration showed promising results. However, the obtained results did not show a specific treatment combination as the best treatment and 1-MCP did not alter the sensory qualities of the processed product.

Alleviation of cold damage to photosystem II and metabolisms by melatonin in Bermudagrass.

As a typical warm-season grass, Bermudagrass [Cynodon dactylon (L).Pers.] is widely applied in turf systems and animal husbandry. However, cold temperature is a key factor limiting resource utilization for Bermudagrass. Therefore, it is relevant to study the mechanisms by which Burmudagrass responds to cold. Melatonin is a crucial animal and plant hormone that is responsible for plant abiotic stress responses. The objective of this study was to investigate the role of melatonin in cold stress response of Bermudagrass. Wild Bermudagrass pre-treated with 100 μM melatonin was subjected to different cold stress treatments (−5°C for 8 h with or without cold acclimation). The results showed lower malondialdehyde (MDA) and electrolyte leakage (EL) values, higher levels of chlorophyll, and greater superoxide dismutase and peroxidase activities after melatonin treatment than those in non-melatonin treatment under cold stress. Analysis of chlorophyll a revealed that the chlorophyll fluorescence transient (OJIP) curves were higher after treatment with melatonin than that of non-melatonin treated plants under cold stress. The values of photosynthetic fluorescence parameters increased after treatment with melatonin under cold stress. The analysis of metabolism showed alterations in 46 metabolites in cold-stressed plants after melatonin treatment. Among the measured metabolites, five sugars (arabinose, mannose, glucopyranose, maltose, and turanose) and one organic acid (propanoic acid) were significantly increased. However, valine and threonic acid contents were reduced in melatonin-treated plants. In summary, melatonin maintained cell membrane stability, increased antioxidant enzymes activities, improved the process of photosystem II, and induced alterations in Bermudagrass metabolism under cold stress.

Analysis of the physiological responses of the plane and willow trees against air pollution in Tehran .

Trees can improve air quality, but at the same time, pollution might put them at risk. Plane(Platanus orientalis L) and willow trees (Salix babylonicaL) are important trees in the green space of Tehran. Plane trees in Tehran have experienced early autumn in recent years due to severe air pollution. The present study, investigated some physiological traits of these trees under study to determine the cause of early autumn phenomenon. Three regions in Tehran were chosen for the study: Sadra Park as a clean region, Al-Mahdi Park as the polluted region 1, and Avesta Park as the polluted region 2. The results showed that the highest levels of chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, and anthocyanins were observed in the leaves of the plane trees of Sadra Park and the leaves of the willow trees of the Avesta Park and Sadra Park. The average concentration of lead (Pb) in the plane leaves was observed in the Avesta Park and the highest cadmium concentration was recorded for the Sadra Park while the concentration of these two metals in the leaves of willow trees in the three regions were not significantly different. This may suggest that the willow trees, by an increase in the amount of anthocyanins of their leaves, prevent the reduction of the amount of photosynthetic pigments under the influence of air pollution. By late spring, the two plants could relatively preserve similar amounts of lead and cadmium in their leaves.

Structure of late summer phytoplankton community in the Firth of Lorn (Scotland) using microscopy and HPLC-CHEMTAX

The Firth of Lorn is at the mouth of one of Scotland's largest fjordic sea lochs, Loch Linnhe. This sea loch, which is fed by a number of other inner lochs, supplies a significant flow of freshwater, which frequently causes the stratification of the water column. To investigate how environmental conditions influence the spatial distribution of phytoplankton in this region water samples were collected for phytoplankton (pigments and microscopy), and other environmental variables including nutrients. Chemotaxonomy was used to estimate the contribution of different taxonomic groups to total chlorophyll a (phytoplankton biomass index). Good agreement was obtained between chemotaxonomy and microscopy data. The highest levels of chlorophyll a (∼2.6 mg m−3) were found in the vicinity of Oban Bay, where cryptophytes, the most abundant group, dinoflagellates and other flagellates thrived in the stratified water column. Centric diatoms, mainly Chaetoceros sp. and Skeletonema costatum, were associated with NH4 and SiO2 concentrations and stratification, while pennate diatoms, mainly Cylindrotheca sp. and Nitzchia sp., were found to be associated with NO3+NO2 and high surface mixed layer depths. Four diatom groups were identified in accordance to their surface to volume ratios, as well as their affinity to environmental parameters (nutrients) and turbulence. This study used a combination of physico-chemical data, classical microscopy methods (appropriate for large cells > 20 μm) and HPLC-CHEMTAX approaches (for large and small cells) to evaluate the distribution of phytoplankton functional groups in a fjordic coastal area.

A bloom of cyanobacteria (Cylindrospermopsis raciborskii) in UHE Carlos Botelho (Lobo/Broa) reservoir: a consequence of global change?

; periodic turbulence with re-oxygenation of the whole water column, and high saturation of oxygen (80-100%); low retention time (< 20 days) and a extensive macrophyte grow in the headwaters that prevent high nutrient load. This is the picture for the last 44 years. The phytoplankton composition was consistent with the oligomesotrophic characteristic of the reservoir: predominance of diatoms and chlorophyceae with a maximum of 10µg/l chlorophyll. However in the winter of (july) 2014 the following changes were observed: a heavy bloom of cyanobacteria occurred for the first time in the reservoir. This cyanobacteria Cylindrospermopsis raciborskii, is a invasive species. Very high chlorophyll levels (up to 100µg/l) were measured and high concentration and input of phosphorus was also detected (Tundisi and Matsumura-Tundisi, 2014). The explanation for this sudden appearance of blooms, can be attributed to the following factors: increase of up to 2°C above the average water temperature during the winter; lower rainfall during summer (30% less of the yearly average of 1.500 mm). Increase in the retention time (from <20 days up to 60 days) in order to maintain volumes for hydroelectricity production. This cyanobacteria bloom can be attributed to changes in the regional climate and the hydrological regime, with consequences for the dam operation. As described by Paerl and Huisman (2008), global warming affects patterns of precipitation and drought. The changes in the hydrological cycle enhanced cyanobacterial dominance. Heavy rains after extensive drought periods, increase nutrient input promoting phytoplankton growth. During periods of drought ,residence time, increase, thus promoting blooms.

The occurrence and levels of cyanotoxin nodularin from Nodularia spumigena in the alkaline and salty Lake Burdur, Turkey

The occurrence of cyanobacteria species Nodularia spumigena and its toxin nodularin were studied in Burdur Lake, a saline alkaline lake with endemic fauna and a Ramsar site of ornithological importance. The water samples were collected from three different locations of Lake Burdur between May and November of 2011. Abundance of Nodularia spumigena and the nodularin levels peaked at the end of July (112,147 cells mL -1 and 4.82 µg L -1 ), coinciding with the highest levels of chlorophyll a (Chl a ) (27.15 µg L -1 ) and the water temperature (29 o C). Although fish or other animal deaths were not detected during the episodes, it is concluded that N. spumigena blooming should be monitored in Burdur Lake for the ecosystem and environmental health.

Lipophilic pigments differentially respond to drying methods in tea (Camellia sinensis L.) leaves

This study evaluated the effectiveness of drying methods in tea leaves on lipid soluble pigments. Tea leaves were conventionally steamed, freeze-dried, room temperature-dried, oven-dried, or microwave-dried and afterward 6 lipophilic pigments were identified using the high performance liquid chromatography approach. While conventional drying resulted in evenly distributed total higher pigment metabolites, the freeze drying method resulted in highest levels of chlorophyll, lutein, and β-carotene. Room temperature drying resulted in the lowest contents of pigment metabolites, and the microwave drying method had uniformly moderate levels of metabolites. The levels of these lipophilic pigments were visualized using a heatmap and co-correlated according to the drying method. The principal component analysis scores plot shows that a relatively close linkage appeared between fresh leaves and the room temperature drying method as well as between the conventional and microwave drying methods. The conventional, freeze, room temperature, and microwave drying methods resulted in differential correlations among the pigment metabolites; in other words, drying method affects final ratios of pigment metabolites amongst themselves. Both the freeze drying method as well as the microwave drying method appear to better maintain pigment metabolite contents, compared to the conventional drying method, and could replace the conventional method for these reasons.

Improving Rice Ability to Degrade Different Polycyclic Aromatic Hydrocarbons Through Multigene Transformation of a Hybrid Dioxygenase System

The widespread presence and potential harm conferred by polycyclic aromatic hydrocarbons (PAHs) to various organisms have raised increased research interest on these pollutants. Plants lack of efficient PAH degradation genes so that they had to suffer from PAH stress. To improve the ability of plants to tolerate various PAHs, four genes, namely nidA and nidB (encoding the large and small subunits of naphthalene dioxygenase of Mycobacterium vanbaalenii PYR-1) as well as nahAa and nahAb (encoding flavoprotein reductase and ferredoxin of the electron-transport chain of the Pseudomonas putida G7 naphthalene dioxygenase system), were ectopically expressed in rice. The hybrid multicomponent naphthalene dioxygenase can assemble correctly and break down PAHs powerfully. Transgenic rice plants exhibited enhanced tolerance toward two- to four-ring PAHs. PAH tolerance in transgenic plants was associated with high chlorophyll levels and photosynthesis efficiency, normal development, and minimal ion leakage under PAH stress. The naphthalene metabolic pathway in transgenic plants mainly involves the dioxygenase pathway. Our results indicate that grafting the naphthalene dioxygenase system into plants is useful to degrade PAHs efficiently in vivo and improve the plant tolerance to the pollutants. This study had introduced a suitable strategy to accelerate the bioremediation process of PAH-contaminated soil under waterlogged conditions and improve the food safety in contaminated area.

Growth and Nutrient Content of Trifoliate Orange Seedlings Influenced by Arbuscular Mycorrhizal Fungi Inoculation in Low Magnesium Soil

A pot experiment was conducted to examine the effects of arbuscular mycorrhizal fungi, Glomus versiforme, G. mosseae, and G. intraradices on growth and nutrition of trifoliate orange (Poncirus trifoliata) seedlings under magnesium (Mg)-nontreated and Mg-treated conditions. Whether treated with Mg or not, G. versiforme inoculation significantly enhanced the growth and concentrations of Mg, phosphorus, calcium, potassium, zinc, and copper in shoots or roots, and activities of acid phosphatase, catalase, invertase, and urease in rhizosphere soils. Additionally, there were higher levels of chlorophyll, proline, soluble sugar and protein in leaves, root viability, superoxide dismutase, peroxidase and catalase in leaves and roots, but lower malondialdehyde content in leaves and roots of mycorrhizal seedlings than non-mycorrhizal ones. Data demonstrated that G. versiforme-inoculated citrus seedlings exhibited higher levels of soil enzymes, osmoregulation, and antioxidant matters, leading to improvement of growth and nutrition of seedlings in low Mg soil.

Dynamics of the growth, life history transformation and photosynthetic capacity of Oophila amblystomatis (Chlorophyceae), a green algal symbiont associated with embryos of the northeastern yellow spotted salamander Ambystoma maculatum (Amphibia)

The recent discovery that the unicellular green alga Oophila amblystomatis, invades embryonic tissues and cells of the salamander Ambystoma maculatum prompted us to investigate the growth and life history transformations of the algal symbionts in egg capsules. During embryonic development, symbionts were first detected microscopically as a cohesive population of swimming cells in the vicinity of the blastopore around embryonic stage 17. This population of cells grew and at embryonic stage 25, a fraction of the population began to affix to the inside of the egg capsule. Cells then underwent syngamy, lost flagella, and transformed into non-motile cells. We observed a linear increase in the accumulation of such capsule-associated cells from embryonic stage 25 to 40. The population of zoospores did not grow over this period and showed a declining trend between stage 39 and 40. We verified the population growth by measuring relative chlorophyll a content and also measured quantum yield (QY) of photosystem II (PS II) using pulse amplitude modulated (PAM) fluorometry. The population, but not the cell size, of non-motile capsule membrane-bound cells increased modestly during a one-month period after hatching, and continued to contain high levels of chlorophyll a and photosynthetic capacity. We conclude that O. amblystomatis undergoes a life history transition in egg capsules and speculate that many of these symbionts become zygotes, rather than invading the embryo.

Foliage identification of different autochtonous common cyclamen genotypes (Cyclamen purpurascens Mill.) using various biochemical parameters

In order to evaluate the potential of common cyclamen (Cyclamen purpurascens Mill.) for the use for foliage ornamentals sixteen genotypes were collected from different regions in Slovenia. Cyclamen plants were classified into four groups based on their foliage characteristics: green, marbled, semi-silvery and silvery group. Leaves were analyzed in autumn and winter. Colour characteristics were colorimetrically evaluated, chlorophyll and carotenoid content was measured spectrophotometrically and anthocyanin and flavonol content were determined with the use of HPLC-PDA-MSn. A detailed analysis revealed that cyclamen leaves grouped into various types differed in numerous parameters. Colour measurements exposed changes between autumn and winter leaves and also among different genotypes. Marbled and semi-silvery genotypes tended to develop more red and pink colouration in autumn, whereas during the winter period the red and pink colouration was only observed in marbled genotypes. The latter were also characterized by high levels of anthocyanins. Semi-silvery, green and marbled genotypes accumulated high levels of chlorophyll (a, b, total) particularly in autumn leaves. Leaves of green and marbled cyclamen types contained high levels of different quercetin and myricetin compounds, as well as higher laricitrin and kaempferol levels compared to semi-silvery and silvery genotypes. Oppositely, isoharmnetine-3-rutinoside and neohesperidine concentrations prevailed in marbled and silvery genotypes.

Pyramiding of ozone tolerance QTLs OzT8 and OzT9 confers improved tolerance to season-long ozone exposure in rice

Tropospheric ozone concentrations are rising in parts of the world which rely heavily on rice as the major staple crop. Therefore, limiting ozone induced rice yield losses through the breeding of adapted varieties constitutes an important contribution to the food security of rice consumers. In this study we crossed two chromosome segment substitution lines (SL) containing individual ozone tolerance QTLs, OzT8 and OzT9, to obtain four lines with tolerance alleles at both loci. The OzT8/OzT9 lines were tested in a season long ozone fumigation experiment (100nLL−1, 8h per day, versus no ozone control) along with their sensitive parent Nipponbare, and SL46 (OzT8) and SL41 (OzT9) containing single QTLs. The OzT8/OzT9 lines showed significantly lower leaf bronzing than Nipponbare throughout the season, which was consistent with a significantly lower level of lipid peroxidation. In addition OzT8/OzT9 lines tended to have higher net photosynthetic rate despite lower stomatal conductance, and higher chlorophyll levels. These physiological advantages led to superior yield performance under ozone stress. Total biomass and shoot biomass yield were drastically reduced by 55 and 52% in Nipponbare, but for the OzT8/OzT9 lines reductions ranged only between 36–41% and 25–37%, respectively. Similarly the spikelet number/panicle and the spikelet number/plant were reduced by 35% and 46% in Nipponbare, but only by 15–18% and 29–34% in the OzT8/OzT9 lines. Overall, our data suggest that the pyramiding of OzT8 and OzT9 led to synergies resulting in superior yield performance under ozone stress.