Molecular mechanisms involved in postharvest chilling tolerance of pomegranate fruit.

Cold storage of pomegranates is essential for prolonging postharvest storage and for the implementation of cold-quarantine insect disinfestation treatments required for international trading. However, pomegranates are chilling sensitive; they may develop chilling injuries upon exposure to unfavorable low temperatures. In this mini-review, we summarize molecular data obtained from three different RNA Seq transcriptome analyses of responses of pomegranate fruits to cold storage. These experiments included comparisons among the transcriptomic responses following a 2-week exposure to 1 °C in three different model systems: 1) unconditioned chilling-sensitive fruits versus relatively chilling-tolerant low-temperature-conditioned fruits; 2) chilling-sensitive early harvested fruits versus relatively chilling-tolerant late-harvested ones; and 3) chilling-sensitive 'Ganesh' variety versus the relatively chilling-tolerant 'Wonderful' variety. Comparisons among differentially expressed transcripts that were exclusively and significantly up-regulated in the relatively chilling-tolerant fruits in all three model systems enabled identification of 573 common chilling tolerance-associated genes in pomegranates. Functional categorization and classification of the differentially expressed transcripts revealed several regulatory, metabolic, and stress-adaptation pathways that were uniquely activated in response to cold storage in relatively chilling-tolerant fruits. More specifically, we identified common up-regulation of transcripts involved in activation of jasmonic acid and ethylene hormone biosynthesis and signaling, stress-related transcription factors, calcium and MAPK signaling, starch degradation and galactinol and raffinose biosynthesis, phenol biosynthesis, lipid metabolism, and heat-shock proteins. We hypothesized these pathways to be involved in imparting chilling tolerance to pomegranate fruits. © 2019 Society of Chemical Industry.

Evaluation of an extract of the Punica granatum flower as a biological stain of rat tissues: a preliminary study.

Natural dyes and especially hematoxylin, which is herbal, are widely used in staining tissues. The aim of this study is to evaluate the staining status of different tissues taken from rats with pomegranate flower extract. For this reason, 2 Wistar albino rats, one male and one female, were used as stain biomaterial. A histological follow up procedure was applied to the lung, kidney, liver, and heart tissue samples taken from the rats and the unstained preparates of these tissues were prepared. As the source of the dye, the dry flowers of Punica granatum (PG) obtained from local markets of Kayseri were used. Each tissue sample underwent the same staining procedure with the same temperature, duration, and dye solution. Before and after the staining procedure, × 40 images of the tissue preparates were taken using a light microscope. Generally, different tones of staining were observed in the nuclei and cytoplasms of all cells and epithelium cells. Staining in parts specific to each tissue occurred. For example, there were light stains on the glomerular cells and the Bowman capsule in the kidney tissue Differences in staining can only be explained by molecular diversity differences in tissue. However, in order to improve the initial staining results obtained in this study, it is possible that working with different temperatures, pH values, mordant substances, and dye that the dye molecules in the extract will provide more vivid colors with different molecules in the tissues.

Cross-talk between physiological and biochemical adjustments by Punica granatum cv. Dente di cavallo mitigates the effects of salinity and ozone stress.

Plants are exposed to a broad range of environmental stresses, such as salinity and ozone (O3), and survive due to their ability to adjust their metabolism. The aim of this study was to evaluate the physiological and biochemical adjustments adopted by pomegranate (Punica granatum L. cv. Dente di cavallo) under realistic field conditions. One-year-old saplings were exposed to O3 [two levels denoted as ambient (AO) and elevated (EO) O3 concentrations] and salinity [S (salt, 50 mM NaCl)] for three consecutive months. No salt (NS) plants received distilled water. Despite the accumulation of Na+ and Cl- in the aboveground biomass, no evidence of visible injury due to salt (e.g. tip yellow-brown lesions) was found. The maintenance of leaf water status (i.e. unchanged values of electrolytic leakage and relative water content), the significant increase of abscisic acid, proline and starch content (+98, +65 and +59% compared to AO_NS) and stomatal closure (-24%) are suggested to act as adaptive mechanisms against salt stress in AO_S plants. By contrast, EO_NS plants were unable to protect cells against the negative impact of O3, as confirmed by the reduction of the CO2 assimilation rate (-21%), accumulation of reactive oxygen species (+10 and +225% of superoxide anion and hydrogen peroxide) and malondialdehyde by-product (about 2-fold higher than AO_NS). Plants tried to preserve themselves from further oxidative damage by adopting some biochemical adjustments [i.e. increase in proline content (+41%) and induction of catalase activity (8-fold higher than in AO_NS)]. The interaction of the two stressors induced responses considerably different to those observed when each stressor was applied independently. An analysis of the antioxidant pool revealed that the biochemical adjustments adopted by P. granatum under EO_S conditions (e.g. reduction of total ascorbate; increased activities of superoxide dismutase and catalase) were not sufficient to ameliorate the O3-induced oxidative stress.

Anatomical explanations for acute depressions in radial pattern of axial sap flow in two diffuse-porous mangrove species: implications for water use.

Mangrove species have developed uniquely efficient water-use strategies in order to survive in highly saline and anaerobic environments. Herein, we estimated the stand water use of two diffuse-porous mangrove species of the same age, Sonneratia apetala Buch. Ham and Sonneratia caseolaris (L.) Engl., growing in a similar intertidal environment. Specifically, to investigate the radial patterns of axial sap flow density (Js) and understand the anatomical traits associated with them, we measured axial sap flow density in situ together with micromorphological observations. A significant decrease of Js was observed for both species. This result was accompanied by the corresponding observations of wood structure and blockages in xylem sapwood, which appeared to influence and, hence, explained the acute radial reductions of axial sap flow in the stems of both species. However, higher radial resistance in sapwood of S. caseolaris caused a steeper decline of Js radially when compared with S. apetala, thus explaining the latter's more efficient use of water. Without first considering acute reductions in Js into the sapwood from the outer bark, a total of ~55% and 51% of water use would have been overestimated, corresponding to average discrepancies in stand water use of 5.6 mm day-1 for S. apetala trees and 2.5 mm day-1 for S. caseolaris trees. This suggests that measuring radial pattern of Js is a critical factor in determining whole-tree or stand water use.

Phytoremediation potential of water caltrop (Trapa natans L.) using municipal wastewater of the activated sludge process-based municipal wastewater treatment plant.

Phytoremediation experiments were carried out to assess the phytoremediation potential of water caltrop (Trapa natans L.) using municipal wastewater collected from the activated sludge process- (ASP) based municipal wastewater treatment plant. The results revealed that T. natans significantly (P ≤ .05/P ≤ .01/P ≤ .001) reduced the contents of total dissolved solids (TDS), electrical conductivity (EC), biochemical oxygen demand (BOD5), chemical oxygen demand, total Kjeldahl nitrogen, phosphate ([Formula: see text]), sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), zinc (Zn), standard plate count, and most probable number of the municipal wastewater after phytoremediation experiments. The maximum removal of these parameters was obtained at 60 days of the phytoremediation experiments, but the removal rate of these parameters was gradually increased from 15 to 45 days and it was slightly decreased at 60 days. Most contents of Cd, Cu, Fe, Mn and Zn were translocated in the leaves of T. natans, whereas most contents of Cr and Pb were accumulated in the root of T. natans after phytoremediation experiments. The contents of different biochemical components were recorded in the order of total sugar > crude protein > total ash > crude fiber > total fat in T. natans after phytoremediation of municipal wastewater. Therefore, T. natans was found to be effective for the removal of different parameters of municipal wastewater and can be used effectively to reduce the pollution load of municipal wastewater drained from the ASP-based treatment plants.

Are Photosynthetic Characteristics and Energetic Cost Important Invasive Traits for Alien Sonneratia Species in South China?

A higher photosynthesis and lower energetic cost are recognized as important characteristics for invasive species, but whether these traits are also important for the ability of alien mangrove species to become invasive has seldom been reported. A microcosm study was conducted to compare the photosynthetic characteristics, energetic cost indices and other growth traits between two alien species (Sonneratia apetala and S. caseolaris) and four native mangrove species over four seasons in a subtropical mangrove nature reserve in Shenzhen, South China. The aim of the study was to evaluate the invasive potential of Sonneratia based on these physiological responses. The annual average net photosynthetic rate (Pn), stomatal conductance (Gs) and total carbon assimilation per unit leaf area (Atotal) of the two alien Sonneratia species were significantly higher than the values of the native mangroves. In contrast, the opposite results were obtained for the leaf construction cost (CC) per unit dry mass (CCM) and CC per unit area (CCA) values. The higher Atotal and lower CC values resulted in a 72% higher photosynthetic energy-use efficiency (PEUE) for Sonneratia compared to native mangroves, leading to a higher relative growth rate (RGR) of the biomass and height of Sonneratia with the respective values being 51% and 119% higher than those of the native species. Higher photosynthetic indices for Sonneratia compared to native species were found in all seasons except winter, whereas lower CC values were found in all four seasons. The present findings reveal that alien Sonneratia species may adapt well and become invasive in subtropical mangrove wetlands in Shenzhen due to their higher photosynthetic characteristics coupled with lower costs in energy use, leading to a higher PEUE. The comparison of these physiological responses between S. apetala and S. caseolaris reveal that the former species is more invasive than the latter one, thus requiring more attention in future.

Physiological and metabolomic analysis of Punica granatum (L.) under drought stress.

MAIN CONCLUSION: Punica granatum has a noticeable adaptation to drought stress. The levels of the green leaf volatile trans-2-hexenal increased in response to drought stress suggesting a possible role of this compound in drought stress response in pomegranate. Punica granatum (L.) is a highly valued fruit crop for its health-promoting effects and it is mainly cultivated in semi-arid areas. Thus, understanding the response mechanisms to drought stress is of great importance. In the present research, a metabolomics analysis was performed to evaluate the effects of drought stress on volatile organic compounds extracted from the leaves of pomegranate plants grown under water shortage conditions. The time course experiment (7 days of water deprivation and 24-h recovery) consisted of three treatments (control, drought stress, and rehydration of drought-stressed plants). Plant weights were recorded and control plants were irrigated daily at pot capacity to provide the lost water. Fraction of transpirable soil water has been evaluated as indicator of soil water availability in stressed plants. The levels of proline, hydrogen peroxide and lipid peroxidation as well as of the photosynthetic parameters such as photosynthesis rate (A), stomatal conductance (g s), photosynthetic efficiency of photosystem II, and photochemical quenching were monitored after the imposition of drought stress and recovery as markers of plant stress. Constitutive carbon volatile components were analyzed in the leaf of control and drought-stressed leaves using Head Space Solid Phase Micro Extraction sampling coupled with Gas Chromatography Mass Spectrometry. A total of 12 volatile compounds were found in pomegranate leaf profiles, mainly aldehydes, alcohols, and organic acids. Among them, the trans-2-hexenal showed a significant increase in water-stressed and recovered leaves respect to the well-watered ones. These data evidence a possible role of the oxylipin pathway in the response to water stress in pomegranate plants.

Negative effects of heterospecific pollen receipt vary with abiotic conditions: ecological and evolutionary implications.

BACKGROUND AND AIMS: Studies that have evaluated the effects of heterospecific pollen (HP) receipt on plant reproductive success have generally overlooked the variability of the natural abiotic environment in which plants grow. Variability in abiotic conditions, such as light and water availability, has the potential to affect pollen-stigma interactions (i.e. conspecific pollen germination and performance), which will probably influence the effects of HP receipt. Thus, a more complete understanding of the extent, strength and consequences of plant-plant interactions via HP transfer requires better consideration of the range of abiotic conditions in which these interactions occur. This study addresses this issue by evaluating the effects of two HP donors (Tamonea curassavica and Angelonia angustifolia) on the reproductive success of Cuphea gaumeri, an endemic species of the Yucatan Peninsula. METHODS: Mixed (conspecific pollen and HP) and pure (conspecific pollen only) hand-pollinations were conducted under varying conditions of water and light availability in a full factorial design. Reproductive success was measured as the number of pollen tubes that reached the bottom of the style. KEY RESULTS: Only one of the two HP donors had a significant effect on C. gaumeri reproductive success, but this effect was dependent on water and light availability. Specifically, HP receipt caused a decrease in pollen tube growth, but only when the availability of water, light or both was low, and not when the availability of both resources was high. CONCLUSIONS: The results show that the outcome of interspecific post-pollination interactions via HP transfer can be context-dependent and vary with abiotic conditions, thus suggesting that abiotic effects in natural populations may be under-estimated. Such context-dependency could lead to spatial and temporal mosaics in the ecological and evolutionary consequences of post-pollination interactions.

Quality changes of fresh-cut pomegranate arils during shelf life as affected by deficit irrigation and postharvest vapour treatments.

BACKGROUND: The effect of two sustained deficit irrigation (SDI) strategies, compared to a control, on postharvest physicochemical, microbial, sensory quality attributes and anthocyanin content of fresh-cut pomegranates arils throughout 18 days at 5 °C was studied. Furthermore, the effect of vapour treatments (4, 7 and 10 s) compared to a conventional sanitizing treatment with NaClO on such quality parameters in combination with the preharvest treatments was also studied. RESULTS: According to sensory analyses, the shelf life of arils from control and SDI-irrigated fruit was established in 14 and 18 days at 5 °C, respectively, showing 4 and 7 s vapour treatment time the best sensory quality. No significant change was observed in physicochemical quality attributes, across all treatments during storage, while low microbial loads were registered (<3 log CFU g(-1)) after shelf life. Postharvest treatments that had least effect on anthocyanin content on processing day were 7 and 10 s. CONCLUSION: Vapour treatments of 7-10 s applied to pomegranate arils led to an extended shelf life up to 18 days at 5 °C with better results in SDI-irrigated samples with a water saving of 6-11%.

An inverse relationship between allelopathic activity and salt tolerance in suspension cultures of three mangrove species, Sonneratia alba, S. caseolaris and S. ovata: development of a bioassay method for allelopathy, the protoplast co-culture method.

A bioassay method for allelopathy, the 'protoplast co-culture method' was developed to study the relationship between salt tolerance and allelopathy of three mangrove species, Sonneratia alba, S. caseolaris, and S. ovata. Plants of S. alba grow in the seaward-side high salinity region and plants of the latter two species grow in upstream-side regions of a mangrove forest, respectively. Effects of five sea salts (NaCl, KCl, MgCl2, MgSO4 and CaCl2) on the growth of the suspension cells of the latter two species were first investigated by a small-scale method using 24-well culture plates. S. ovata cells showed higher tolerance than S. caseolaris cells to NaCl and other salts, but were not as halophilic as S. alba cells. Protoplasts isolated from suspension cells were co-cultured with lettuce protoplasts in Murashige and Skoog's (MS) basal medium containing 1 µM 2,4-dichlorophenoxyacetic acid, 0.1 µM benzyladenine, 3% sucrose and 0.6-0.8 M osmoticum. S. caseolaris protoplasts had a higher inhibitory effect on lettuce protoplast cell divisions than S. alba protoplasts at any lettuce protoplast density, and the effect of S. ovata was intermediate between the two. These results were similar to those obtained from a different in vitro bioassay method for allelopathy, the 'sandwich method' with dried leaves. The inverse relationship between allelopathic activity and salt tolerance in suspension cells of Sonneratia mangroves is discussed.

Long-term differences in annual litter production between alien (Sonneratia apetala) and native (Kandelia obovata) mangrove species in Futian, Shenzhen, China.

Annual litter production in alien (Sonneratia apetala) and native (Kandelia obovata) mangrove forests in Shenzhen, China were compared from 1999 to 2010. S. apetala had significantly higher litter production than K. obovata, with mean annual total litter of 18.1 t ha(-1) yr(-1) and 15.2 t ha(-1) yr(-1), respectively. The higher litter production in S. apetala forest indicates higher productivity and consequently more nutrient supply to the estuarine ecosystems but may be more invasive due to positive plant-soil feedbacks and nutrient availability to this alien species. Two peaks were recorded in S. apetala (May and October), while only one peak was observed in K. obovata, in early spring (March and April). Leaf and reproductive materials were the main contributors to litter production (>80%) in both forests. These results suggest that the ecological function of S. apetala and its invasive potential can be better understood based on a long-term litter fall analysis.

Utilization of water chestnut for reclamation of water environment and control of cyanobacterial blooms.

Overgrowth of water chestnut (Trapa spp.) is a regional problem throughout Asia and North America because of waterway blockage and water fouling upon decomposition. In the present study, we investigated the potential of water chestnut to control cyanobacterial blooms, via a high content of phenolic compounds. In addition, we assessed the impact of biomass harvesting and crude extract application on nutrient balance. We showed that the floating parts of water chestnut contained high concentrations of total phenolics (89.2 mg g(-1) dry weight) and exhibited strong antioxidant activity (1.31 mmol g(-1) dry weight). Methanol-extracted phenolics inhibited growth of Microcystis aeruginosa; the half maximal effective concentration (EC50) of the extracted phenolics was 5.8 mg L(-1), which was obtained from only 103 mg L(-1) of dry biomass (the floating and submerged parts). However, the crude extracts also added important quantities of nitrogen, phosphorus, and potassium (1.49, 1.05, and 16.3 mg g(-1), respectively; extracted dry biomass weight basis); therefore, in practice, nutrient removal before and/or after the extraction is essential. On the other hand, biomass harvesting enables recovery of nitrogen, phosphorus, and potassium from the water environment (23.1, 2.9, and 18.7 mg g(-1), respectively; dry biomass weight basis). Our findings indicate that water chestnut contains high concentrations of phenolics and exhibits strong antioxidant activity. Utilization of these resources, including nutrients, will contribute to reclamation of the water environment, and also to disposal of wet biomass.

Evidence for pollen limitation of a native plant in invaded communities.

Animal-pollinated invasive species have frequently been demonstrated to outcompete native species for pollinator attention, which can have detrimental effects on the reproductive success and population dynamics of native species. Many animal-pollinated invasive species exhibit showy flowers and provide substantial rewards, allowing them to act as pollinator 'magnets', which, at a large scale, can attract more pollinators to an area, but, at a smaller scale, may reduce compatible pollen flow to local native species, possibly explaining why most studies detect competition. By performing pollen limitation experiments of populations in both invaded and uninvaded sites, we demonstrate that the invasive plant Lythrum salicaria appears to facilitate, rather than hinder, the reproductive success of native confamilial Decodon verticillatus, even at a small scale, in a wetland habitat in southeastern Ontario. We found no evidence for a magnet species effect on pollinator attraction to invaded sites. Germination experiments confirmed that seeds from invaded sites had similar germination rates to those from uninvaded sites, making it unlikely that a difference in inbreeding was masking competitive effects. We describe several explanations for our findings. Notably, there were no differences in seed set among populations at invaded and uninvaded sites. Our results underscore the inherent complexity of studying the ecological impacts of invasive species on natives.

[Synergistic effects of low temperature in winter and ebb tide at night on Sonneratia apetala seedlings growth and key eco-physiological traits].

By setting up a set of simulated tidal systems with different air- and water temperature and tidal flood conditions, this paper studied the synergistic effects of low temperature in winter and ebb tide at night on the growth and key eco-physiological traits of Sonneratia apetala seedlings. Low air temperature depressed the seedlings growth, but the reduction in the seedling height and basal stem diameter was compensated 41.2% and 44.6%, respectively by a 5 degrees C increase of water temperature. Low air temperature (15 degrees C) reduced the leaf Fv/Fm significantly, indicating a dramatic reduction in the leaf photosynthetic capacity, whereas the flooded tide with higher water temperature could not compensate this damage. The flooded tide with high air temperature increased the proline and soluble sugar contents in mature leaves, which could protect the mature leaves from cold damage. When extreme cold events occurred, the flooded tide at night worked as a heat storage medium, which alleviated the cold damage on the seedlings growth and leaf physiological traits, and promoted the survival rate of S. apetala seedlings.

A pomegranate (Punica granatum L.) WD40-repeat gene is a functional homologue of Arabidopsis TTG1 and is involved in the regulation of anthocyanin biosynthesis during pomegranate fruit development.

Anthocyanins are the major pigments responsible for the pomegranate (Punica granatum L.) fruit skin color. The high variability in fruit external color in pomegranate cultivars reflects variations in anthocyanin composition. To identify genes involved in the regulation of anthocyanin biosynthesis pathway in the pomegranate fruit skin we have isolated, expressed and characterized the pomegranate homologue of the Arabidopsis thaliana TRANSPARENT TESTA GLABRA1 (TTG1), encoding a WD40-repeat protein. The TTG1 protein is a regulator of anthocyanins and proanthocyanidins (PAs) biosynthesis in Arabidopsis, and acts by the formation of a transcriptional regulatory complex with two other regulatory proteins: bHLH and MYB. Our results reveal that the pomegranate gene, designated PgWD40, recovered the anthocyanin, PAs, trichome and seed coat mucilage phenotype in Arabidopsis ttg1 mutant. PgWD40 expression and anthocyanin composition in the skin were analyzed during pomegranate fruit development, in two accessions that differ in skin color intensity and timing of appearance. The results indicate high positive correlation between the total cyanidin derivatives quantity (red pigments) and the expression level of PgWD40. Furthermore, strong correlation was found between the steady state levels of PgWD40 transcripts and the transcripts of pomegranate homologues of the structural genes PgDFR and PgLDOX. PgWD40, PgDFR and PgLDOX expression also correlated with the expression of pomegranate homologues of the regulatory genes PgAn1 (bHLH) and PgAn2 (MYB). On the basis of our results we propose that PgWD40 is involved in the regulation of anthocyanin biosynthesis during pomegranate fruit development and that expression of PgWD40, PgAn1 and PgAn2 in the pomegranate fruit skin is required to regulate the expression of downstream structural genes involved in the anthocyanin biosynthesis.

Physiological responses of mangrove Sonneratia apetala Buch-Ham plant to wastewater nutrients and heavy metals.

Mangroves play an important role for removing nutrients, heavy metals, and other pollutants in wetland ecosystems. This study investigated the physiological responses of a mangrove plant (i.e., Sonneratia apetala Buch-Ham) to different wastewater pollution levels. Four different treatments, namely three concentration levels (i.e., normal, five-time-greater than normal, and ten-time-greater than normal) of wastewaters and one control (i.e., salted water), were used to grow the mangrove plants. Results showed that the height and biomass of the plant increased with wastewater pollution levels. No significant differences in root and catalase activities were observed among different treatments, whereas the increases in peroxidase and superoxide dismutase activities were attributed to the need for detoxification. In general, leaf chlorophyll content increased with wastewater pollution levels due to the increase in nutrient contents.

Morpho-physiological and biochemical responses in the floating lamina of Trapa natans exposed to molybdenum.

The response to molybdenum (Mo) was studied in the metal-tolerant hydrophyte Trapa natans L. Previously, it was shown that the plant accumulates Mn in the floating lamina by means of phenolic compounds and responded with acclimation responses of the chloroplast. Since the involvement of phenolics has been proposed also in Mo resistance, we tested the response of T. natans to increasing doses (5, 50, 150, 600 microM) of Mo using the photosynthetic apparatus as an indicator of cellular stress. Only 5 microM Mo did not cause evident modifications with respect to controls. Conversely, 50 to 600 microM Mo induced progressively marked alterations of the lamina morphology. The chloroplast ultrastructure showed disorganisation of the thylakoid system, and correspondingly, the photosynthetic pigment pattern was altered with a fall-down in photosynthesis. Microspectrofluorimetry indicated alterations of photosystem II, with differences among the three cell layers (first and second palisade and spongy tissues). While the highest dose caused plant death, 50 and 150 microM Mo-treated plants underwent partial recovery, and the plant survived up to the end of the vegetative season. However, reproduction was unsuccessful. Mo treatment did not induce increase in total phenolics, but only in anthocyanin. In contrast to Mn, detoxification of Mo by chelation inside vacuoles, possibly by anthocyanins, is suggested to be an insufficient mechanism to reduce Mo toxicity, which probably includes an impairment of nitrogen metabolism. However, the metal was accumulated in the lamina. On the whole, T. natans showed limited capabilities to survive Mo excess as compared with Mn.

Application of Trapa bipinosa for the treatment of pulp and paper industry effluent.

The ability of aquatic plants to absorb, translocate and concentrate metals has led to the development of various plant-based treatment systems. The potential to accumulate metals like iron, nickel, manganese and copper by Trapa bipinosa was assessed by subjecting them to different effluent concentrations of pulp and paper industry under laboratory conditions. Trapa showed the ability to accumulate substantial amounts of the metals during a short span of one week. When the plants were grown in different concentrations they caused significant reduction in various parameters like dissolved oxygen, biological oxygen demand, chemical oxygen demand, total alkalinity total hardness, chloride and sulphate. While there was an increase in biomass, no visible phytotoxic symptoms were shown by treated plants.

Investigation fauna and density of population of spiders in the desert and pomegranate orchards in Tehran and Semnan provinces.

The present study was carried out to consideration the spider's fauna and abundance of spiders in the desert and pomegranate orchards in Tehran and Semnan provinces, during 2007. Specimens were collected from desert and pomegranate orchards by pitfall trap, shaking tree, pans, bottle and aspirator and were taken to the laboratory after labeling. A total of 1231 specimens were classified in 45 species and 36 genera belonged to 17 families. Among them 4 spider species were new for Iranian spider fauna. The families Lycosidae, Linyphiidae, Gnaphosidae and Theridiidae had height population in the study areas. Specimens were immature in the winter and spring and they were adult in the summer. The dominant species in all of study regions was Pardosa agrestis (Westring).

Pigments, photosynthesis and photoinhibition in two amphibious plants: consequences of varying carbon availability.

In the present study, we investigated the effects of CO(2) availability on photosynthesis, photoinhibition and pigmentation in two species of amphibious plants, Lobelia cardinalis and Nesaea crassicaulis. The plants were grown emergent under atmospheric conditions and submerged under low and high CO(2) availability. Compared with Lobelia, Nesaea had thin leaves and few stomata in all CO(2) treatments. While Lobelia expressed no variation in anthocyanin content among treatments, Nesaea produced high concentrations of anthocyanin when submerged. Lobelia photosynthesis increased in response to increasing CO(2) availability, and photoinhibition was negatively related to xanthophyll content. By contrast, Nesaea photosynthesis was highest under submerged conditions, and there was no relationship between photoinhibition and the xanthophyll content. We conclude that the response of Lobelia to varying CO(2) availability is similar to that of terrestrial plants and that this species relies on the xanthophyll cycle for nonphotochemical quenching (NPQ) and protection against photoinhibition. By contrast, the thin leaves, few stomata and low levels of chlorophylls and accessory pigments in Nesaea, relative to Lobelia, suggest adaptation to a submerged habitat. While Nesaea does not seem to rely on the xanthophyll cycle or other xanthophylls for NPQ, some role of anthocyanins in the protection against photoinhibition cannot be ruled out, owing to its effect as a sunscreen and as an efficient quencher of free radicals.