Lower Chlorophyll Levels Research Articles

Can exogenous application of putrescine and priming modulate salinity stress in Camelina sativa L?

High salinity in soil significantly reduces growth and productivity; however, employing priming techniques and foliar spraying of putrescine can serve as an impressive method to reduce the impact of salt stress in saline soil. The current investigation intends to explore the effected of foliar spraying and priming methods on the growth, physiological, biochemical characteristics, and seed chemical compositions of salt-stressed Camelina sativa L. crop. A pot test was set up in a randomized complete block design by a factorial scheme with four replications. The experiment involved three factors: 1) salinity stress (0, 60, and 90 mM(, 2) priming techniques (no priming, hydro-priming, putrescine-priming (50 μmol L − 1), and 3) foliar application of putrescine at concentrations of 0, 100, and 200 μmol L−1. Camelina plants subjected to salinity stress showed decreased growth and performance, which correlated with lower chlorophyll levels, reduced photosynthesis maximum quantum efficiency, potassium concentration, and total soluble sugars and proline content. This decline was associated with increased lipid peroxidation (malondialdehyde content), sodium concentration, and electrical leakage, leading to diminished antioxidant enzyme activities. In contrast, under salt stress (60 mM), priming with putrescine led to an increase in grain yield (45 %), chlorophyll content (43 %), shoot length (54 %), maximum quantum efficiency (16 %), Superoxide dismutase (49 %), Catalase (58 %), Ascorbate peroxidase (47 %), linoleic acid (20 %), linolenic acid (38 %), oleic acid (27 %), eicosanoic acid (13 %) and shoot K+ ion (50 %) compared with non-treated plants. The application of 100 μmol L−1 putrescine through foliar application elicited the efficiency of camelina plants with increasing proline content, total soluble sugars, and antioxidant enzyme activities against salinity stress. In addition, the putrescine-priming method could improve photosynthetic efficiency and antioxidant enzyme activity under salt stress levels. Overall, our results supply an important outlook for the use of foliar putrescine spraying and putrescine-priming in modulating salinity tolerance in camelina crops.

Effects of ash dieback on leaf physiology and leaf morphology of Fraxinus excelsior L.

Key messageAsh dieback causes alterations in leaf physiology and morphology, particularly affecting the specific leaf area, which can be used to discriminate between different degrees of damage.Since the introduction of the invasive fungal pathogen Hymenoscyphus fraxineus in Europe, the European common ash (Fraxinus excelsior L.) has been threatened by ash dieback. An infection leads, for example, to typical symptoms of dying shoots, but changes of leaf physiology and morphology are still largely unexplored. Therefore, five physiological and morphological traits, chlorophyll content, chlorophyll fluorescence, specific leaf area, leaf thickness, and fluctuating asymmetry, were investigated in four different study sites in southern Germany regarding possible changes due to ash dieback and their relationship to different degrees of damage. Both higher and lower levels of chlorophyll with increasing damage due to ash dieback were observed. Chlorophyll fluorescence and fluctuating asymmetry proved to be less suitable indicators of damage. Leaf thickness showed the tendency (however not significant) of an increase in more severely damaged trees. The specific leaf area was identified as a suitable indicator of the damage severity, with significant smaller values in less healthy trees. Therefore, ash dieback can also result in notable alterations in leaf physiology and morphology.

Accumulation of Hydrogen Peroxide in Flag Leaves Induces Effective Regeneration of Triticale During Rehydration After Water Stress

A key element in the effective recovery of plants after drought is slowing down of their senescence accelerated during the drought. Therefore, in this paper the relationships between hydrogen peroxide content and effective recovery during rehydration after water stress were analyzed. The study focused on two DH lines of winter triticale with different regeneration potential, as shown by different numbers of lateral stems with ears, grown during rehydration after water stress. During rehydration, the GZDH27 line grows two to three lateral stems with ears, whereas the GZDH88 line grows a single lateral stem with ear. The two DH lines of winter triticale showed comparable responses to the drought stress but their responses to rehydration after the drought stress were clearly different. Results revealed, that the increased accumulation of hydrogen peroxide, which was induced during the drought, can be maintained during rehydration, thus stimulating plant senescence. In the line GZDH88, rehydration did not slow down drought-induced senescence. This was manifested by higher levels of hydrogen peroxide, accompanied by lower levels of chlorophyll in the flag leaves of GZDH88 plants, as the result of which only one lateral stem was formed during rehydration. However, development of one lateral stems during rehydration in the GZDH88 line allowed for smaller yield loss than in the GZDH77 line, that developed of three lateral stems during rehydration. The efficient production of carbohydrates and their effective allocation into the ears of the lateral stems required considerable energy expenditure in the GZDH27 line. Our results indicate that growing three lateral stems with ears during rehydration does not guarantee limitation of grain yield loss. However, to reach the final conclusion, it is important to evaluate a greater number of triticale genotypes under drought stress and rehydration during various stages of a plants development.

Pengaruh Infeksi Virus Kerupuk terhadap Pertumbuhan dan Hasil Tanaman Tembakau Payakumbuh

Limapuluh Kota Regency and Payakumbuh City, West Sumatra Province are the centers for the cultivation of Payakumbuh tobacco plants. The average Payakumbuh tobacco production is still low, namely 0.701 tonnes/ha. One of the causes of low productivity is disease caused by the cracker virus. This research aims to see the effect of naturally infected cracker virus infection on the growth and production of tobacco plants. This research is an observational study, carried out from June to September 2023, at the Payakumbuh State Agricultural Polytechnic experimental garden. The data obtained were processed using the T test at the 5%, level using the Statistical Program for Social Science (SPSS) Version 23 software. From observation and data processing it was found that cracker virus infection caused low levels of chlorophyll A, high levels of chlorophyll B and total leaf chlorophyll levels. plant, leaf length, petiole length, leaf length, leaf width, leaf fresh weight, and root fresh weight, but had no effect on the number of leaves and leaf thickness compared to uninfected plants. From this it can be concluded that cracker virus infection can reduce the growth and yield of Payakumbuh tobacco.

Alleviated lead toxicity in rice plant by co-augmented action of genome doubling and TiO2 nanoparticles on gene expression, cytological and physiological changes

Lead is a very toxic and futile heavy metal for rice plants because of its injurious effects on plant growth and metabolic processes. Polyploidy or whole genome doubling increases the ability of plants to withstand biotic and abiotic stress. Considering the beneficial effects of nanoparticles and tetraploid rice, this research was conducted to examine the effectiveness of tetraploid and titanium dioxide nanoparticles (TiO2 NPs) in mitigating the toxic effects of lead. A diploid (E22-2x) and it's tetraploid (T-42) rice line were treated with Pb (200 μM) and TiO2 NPs (15 mg L−1). Lead toxicity dramatically reduced shoot length (16 % and 4 %) and root length (17 % and 9 %), biological yield (55 % and 36 %), and photosynthetic activity, as evidenced by lower levels of chlorophyll a and b (30 % and 9 %) in E-22 and T-42 rice cultivars compared to the control rice plants, respectively. Furthermore, lead toxicity amplified the levels of reactive oxygen species (ROS), such as malondialdehyde and H2O2, while decreasing activities of all antioxidant enzymes, such as superoxidase, peroxidase, and glutathione predominately in the diploid cultivar. Transmission electron microscopy and semi-thin section observations revealed that Pb-treated cells in E22-2x had more cell abnormalities than T-42, such as irregularly shaped mitochondria, cell wall, and reduced root cell size. Polyploidy and TiO2 reduced Pb uptake in rice cultivars and expression levels of metal transporter genes such as OsHMA9 and OsNRAMP5. According to the findings, genome doubling alleviates Pb toxicity by reducing Pb accumulation, ROS, and cell damage. Tetraploid rice can withstand the toxic effect of Pb better than diploid rice, and TiO2 NPs can alleviate the toxic impact of Pb. Our study findings act as a roadmap for future research endeavours, directing the focus toward risk management and assessing long-term impacts to balance environmental sustainability and agricultural growth.

Under cadmium stress, silicon has a defensive effect on the morphology, physiology, and anatomy of pea (Pisum sativum L.) plants.

Soil pollution with cadmium (Cd) is a serious threat to plant growth and development. On the other hand, silicon (Si) can support plants to cope with Cd stress. However, the Cd stress mitigating impact of Si reduction in pea (Pisum sativum L.) is not known. The objective of this study is to see if and how Si can reduce Cd toxicity. To the end, a greenhouse pot experiment was performed twice during the 2018/2019 and 2019/2020 seasons to investigate the effect of Si on the growth, anatomy, and biochemistry of Cd stressed peas plants. Cd exposure increased the contents of Cd ions in the root and shoot of pea plants. Consequentially, Cd accumulation in pea tissue significantly reduced plant growth i.e., plant height, leaf area, and shoot and root dry weights. The effect of Cd was concentration-dependent, where at low concentration (50 mg/kg soil), the plant height was 94.33 and 97.33cm and at high concentration (100 mg/kg soil), it was 89.0 and 91.0cm in the two seasons, respectively. This growth reduction can be explained by the decrease in plants' photosynthesis, whereas plants exposed to Cd toxicity had lower chlorophyll levels. At the anatomy level, high Cd concentrations resulted in anatomical abnormalities such as an unusual vascular system, abnormal lignification in the pith parenchyma, and enlarged cortical cells. Moreover, all Cd concentrations resulted in a highly significant decrease in stomatal area and stomatal density (the number of stomata per mm2). In addition to growth inhibition, Cd-induced oxidative damage to pea plants as indicated by increased hydrogen peroxide (H2O2) and Malondialdehyde (MDA) levels. To reduce stress toxicity, plants treated with Cd at 50 and 100 (mg/kg) showed a significant increase in antioxidant capacity. Peroxidase (POD) enzyme activity was significantly increased by 41.26%, 28.64%, 77.05%, and 60.77% in both seasons, respectively. Si at 300 ppm under Cd (100 mg/kg) stress conductions considerably reduced (MDA) contents by 29.02% and 29.12%, in the two seasons, respectively. The findings pointed out that Si's ability to protect pea against the oxidative stress caused by Cd toxicity.

Cytological, physiological and transcriptomic analysis of variegated Leaves in Primulina pungentisepala offspring

BackgroundPrimulina pungentisepala is suitable for use as a potted plant because of its beautiful leaf variegation, which is significantly different in its selfed offspring. However, the mechanism of P. pungentisepala leaf variegation is unclear. In this study, two types of offspring showing the greatest differences were compared in terms of leaf structure, chlorophyll contents, chlorophyll fluorescence parameters and transcriptomes to provide a reference for studying the molecular mechanism of structural leaf variegation.ResultsAir spaces were found between water storage tissue, and the palisade tissue cells were spherical in the white type. The content of chlorophyll a and total chlorophyll (chlorophyll a + b) was significantly lower in the white type, but there were no significant differences in the content of chlorophyll b, chlorophyll a/b or chlorophyll fluorescence parameters between the white and green types. We performed transcriptomic sequencing to identify differentially expressed genes (DEGs) involved in cell division and differentiation, chlorophyll metabolism and photosynthesis. Among these genes, the expression of the cell division- and differentiation-related leucine-rich repeat receptor-like kinases (LRR-RLKs), xyloglucan endotransglycosylase/hydrolase (XET/H), pectinesterase (PE), expansin (EXP), cellulose synthase-like (CSL), VARIEGATED 3 (VAR3), and ZAT10 genes were downregulated in the white type, which might have promoted the development air spaces and variant palisade cells. Chlorophyll biosynthesis-related hydroxymethylbilane synthase (HEMC) and the H subunit of magnesium chelatase (CHLH) were downregulated, while chlorophyll degradation-related chlorophyllase-2 (CHL2) was upregulated in the white type, which might have led to lower chlorophyll accumulation.ConclusionLeaf variegation in P. pungentisepala was caused by a combination of mechanisms involving structural variegation and low chlorophyll levels. Our research provides significant insights into the molecular mechanisms of structural leaf variegation.

Summer Distributional Characteristics of Surface Phytoplankton Related with Multiple Environmental Variables in the Korean Coastal Waters

Multiple environmental variables related to ocean currents, freshwater runoff, and upwelling in a coastal area have complex effects on the phytoplankton community. To assess the influence of environmental variables on the phytoplankton community structure during the summer of 2019, we investigated the various abiotic and biotic factors in Korean coastal waters (KCWs), separated into five different zones. Summer environmental factors in KCWs were strongly influenced by Changjiang Diluted Water (CDW) in St. SO (Southern Offshore) 1 and 2, upwelling in St. SI (Southern Inshore) 2–4, and Nakdong River discharge in St. SI 12. In particular, low–salinity water masses (p < 0.05 for nearby locations) of CDW gradually expanded from the East China Sea to southwestern KCWs from June to July. In addition, there were high levels of nutrients following freshwater runoff from the Nakdong River in southeastern KCW, which led to the dominance of Cryptomonas spp. (81%), a freshwater and brackish water algae. On the other hand, upwelling areas in southwestern KCW were dominated by diatoms Skeletonema spp., and are characterized by high phosphate concentrations (p < 0.05) and low temperatures (p < 0.05) compared to nearby locations. Leptocylindrus danicus (20%) was dominant due to the effect of water temperature in the SE (Southeastern area) zone. Low nutrient concentrations were maintained in the East Sea (dissolved inorganic nitrogen (DIN) = 0.39 ± 0.40 μM; dissolved inorganic phosphate (DIP) = 0.09 ± 0.03 μM) and the Yellow Sea (DIN = 0.40 ± 0.07 μM; DIP = 0.04 ± 0.02 μM), which were characterized by low levels of chlorophyll a and dominated by unidentified small flagellates (35, 40%). Therefore, our results indicated that hydro–oceanographic events such as upwelling and freshwater run–off, but not ocean currents, provide nutrients to the euphotic layers of the coastal environment and play important roles in determining the phytoplankton community structure during summer in the KCWs.

Nitrogen inputs influence vegetative metabolism in maize engineered with a seed-specific carotenoid pathway.

Metabolomic profiling of a maize line engineered with an endosperm-specific carotenogenic pathway revealed unexpected metabolic readjustments of primary metabolism in leaves and roots. High-carotenoid (HC) maize was engineered to accumulate high levels of carotenoids in the endosperm. The metabolic interventions influenced the flux through non-target pathways in tissues that were not affected by the targeted intervention. HC maize at the vegetative stage also showed a reduced susceptibility to insect feeding. It is unknown, however, whether the metabolic history of the embryo has any impact on the metabolite composition in vegetative tissues. We, therefore, compared HC maize and its isogenic counterpart (M37W) to test the hypothesis that boosting the carotenoid content in the endosperm triggers compensatory effects in core metabolism in vegetative tissues. Specifically, we investigated whether the metabolite composition of leaves and roots at the V6 stage differs between HC and M37W, and whether N inputs further alter the core metabolism of HC compared to M37W. We found an increase in the abundance of organic acids from the tricarboxylic acid (TCA) cycle in HC even under restricted N conditions. In contrast, low levels of carotenoids and chlorophyll were measured regardless of N levels. Sugars were also significantly depleted in HC under low N. We propose a model explaining the observed genotype-dependent and input-dependent effects, in which organic acids derived from the TCA cycle accumulate during vegetative growth and contribute to the increased demand for pyruvate and/or acetyl-CoA in the endosperm and embryo. This response may in part reflect the transgenerational priming of vegetative tissues in the embryo induced by the increased demand for metabolic precursors during seed development in the previous generation.

Five-weeks pot trial evaluation of phytoremediation potential of Helichrysum splendidum Less. for copper- and lead-contaminated soils

This paper describes an investigation into the accumulation and distribution of Cu and Pb in Helichrysum splendidum, to assess the potential use of the plant in the phytoremediation of Cu- and Pb-contaminated soils. Plants of the same age were exposed to soils artificially contaminated with 10, 50, 100, 500 and 1000 mg/L Cu(II) and Pb(II). Although plant growth was not affected by the presence of Cu, high concentrations of Pb (> 500 mg/L) stunted the plants. Chlorophyll production was slightly reduced when plants were exposed to high concentrations of Cu (> 500 mg/L), whereas all the plants growing in Pb-contaminated soils indicated low levels of chlorophyll. Significant amounts of Cu and Pb were accumulated in the roots, with corresponding bioconcentration factors of > 1. Translocation of Cu to the shoots was restricted for plants growing in > 500 mg/L Cu-treated soils, whereas Pb was translocated to the shoots for all treatments, with translocation factors > 1. The Cu and Pb tolerance mechanism was ascribed to chelation and free radical scavenging, through the production of phenolic compounds. Helichrysum splendidum is able to adapt to and ameliorate soils contaminated with low to high levels of Cu(II) and Pb(II) and has potential for application in phytoextraction and phytostabilization of contaminated soils.

Sediment resuspension drives protist metacommunity structure and assembly in grass carp (Ctenopharyngodonidella) aquaculture ponds

Protists in aquaculture ponds are key components associated with primary productivity, nutrient cycling, and fish healthy. However, the protist metacommunity diversity, as well as the ecological and environmental factors that structure protist metacommunity in aquaculture ponds remain poorly understood. This study examined protist metacommunities in water and sediment of larval, small juvenile and large juvenile grass carp ponds. The results indicated sediment resuspension became stronger with the increased fish size, which led to high levels of total suspended solids and nitrogen but low levels of phosphate, chlorophyll a and transparency in water. Moreover, sediment resuspension subsequently increased the alpha diversity indexes (i.e., OTU number, Shannon index and Simpson index) of protist communities in water and sediment. Meanwhile, sediment resuspension increased the relative abundance of heterotrophic Ciliophora and Cercozoa, but decreased the relative abundance of autotrophic Chlorophyta, Stramenopiles X, and Ochrophyta. Besides, some mixotrophic and heterotrophic protists showed competitive advantages in the turbidity water, which led to the increase of negative interactions in the protist co-occurrence networks. Based on the null model, sediment resuspension strengthened homogeneous selection (deterministic process) and weakened dispersal limitation (stochastic process) processes of protist community assembly. Indeed, protist community dissimilarity within each local community and each habitat (water or sediment) both decreased while the community dissimilarity between habitats increased with the increase of fish size. Therefore, sediment resuspension did not enhance the dispersal path between water and sediment, but decreased the dispersal limitation within sediment and water coupled with the strengthening of environmental selection. These results indicated that grass carp could restructure the protist metacommunity in aquaculture ponds through bottom up way of sediment resuspension. This study advances our understanding of the relationship between fish and protist metacommunity assembly in aquaculture systems.

Comparision of several secondary metabolite and elemental ion contents of leaves from <i> Kandelia obovata </i> and <i> Sonneratia caseolaris </i> forests located in the Red River delta

The two mangrove species Kandelia obovata and Sonneratia caseolaris were widely planted in the Red River delta. Both K. obovata and S. caseolaris forests play an important role in the economic development and environmental protection of the delta. However, chemical responses of the common mangrove forests to different ecological conditions in the delta have not yet been described. In this study, we evaluated chemical responses of K. obovata and S. caseolaris through comparisons of the content of metabolites and element ions in leaves of mangrove plants located under different ecological conditions in the Red River delta. In the low salinity area (Thuy Truong), specific leaf areas of K. obovata and S. caseolaris were much lower while the succulent index was higher compared to those in the high salinity area (Kim Trung). In Kim Trung, both species had a lower ratio of chlorophyll a/chlorophyll b. K. obvata in lower light (under the S. caseolaris canopy) had lower levels of chlorophyll b, resulting in a higher Chla/chlb ratio. There was no difference in the Mg content of leaves between two areas. An increase in Na content in leaves of mangrove plants in the higher salinity area was evident. The high K/Na ratio in leaves were eveluated for both species in high salinity areas. Our results also showed better uptake of K in leaves of S. caseolaris growing in the low salinity conditions (Thuy Truong), i.e. Thuy Truong has more favourable ecological conditions for S. caseolaris. Carotenoid contents in leaves of both species growing in the higher salinity were lower.

Privet golden leaves adapt unexpectedly well to light changes

Golden-leaf privet (Ligustrum × vicaryi) is widely used as a horticultural shrub because of its upper golden leaves, but its lower leaves are green. However, the putative mechanisms of its upper golden leaves and the leaf color changes in response to light shifts have not been well studied so far. Here, chlorophylls (Chl), carotenoids, and Chl precursors from both golden and green leaves grown in full sunlight (approximately 1200 μmol photons m−2 s−1 at noon) or low-light conditions (180 μmol m−2 s−1) were determined spectrophotometrically. In addition, their gas exchange parameters and Chl fluorescence were measured in situ. Metabolic flux analysis of chlorophyll intermediates indicated that the conversion of prochlorophyllide to chlorophyllide was significantly blocked in golden leaves when compared with green leaves. Green leaves showed higher photosynthetic capacity in low light than golden leaves, but golden leaves presented unexpectedly stronger photosynthetic capacity and lower reactive oxygen species accumulation under the high-light condition. Furthermore, golden leaves showed a higher level of nonphotochemical quenching (NPQ) after the light-to-dark shift and presented a stronger adaptive ability to a broad range of light environments. Higher NPQ values and less oxidative damage in golden leaves may be correlated with their higher carotenoid levels. The results imply that lower chlorophyll levels and higher carotenoid levels in canopy leaves may help privet plants acclimate better to illumination changes. This study demonstrates the key role of irradiance in generating the two types of Ligustrum × vicaryi leaves and sheds a light on cultivation of other ornamental foliage plants.

Loss of Function of Fatty Acid Desaturase 7 in Tomato Enhances Photosynthetic Carbon Fixation Efficiency.

Fatty Acid Desaturase 7 (FAD7) generates polyunsaturated fatty acids, promoting the desaturation of chloroplast membranes; it also provides an essential precursor for the synthesis of jasmonic acid (JA), a phytohormone that can influence plant growth, development, and primary metabolism. This study examined the effects of spr2, a null mutation in SlFAD7, on the growth, morphology, and photosynthetic traits of tomato, Solanum lycopersicum. Although the spr2 mutant had a lower density of stomata than wild type plants, the two genotypes had comparable stomatal conductance, transpiration rates, and intracellular CO2 levels; in addition, spr2 had significantly thinner leaf blades, which may help maintain normal levels of CO2 diffusion despite the lower number of stomata. Surprisingly, spr2 also had significantly higher carbon assimilation (A) and maximum quantum efficiency of PSII (Fv/Fm) than wild type plants at both of the light intensities tested here (220 or 440 µmol m−2 s−1), despite having lower levels of chlorophyll than wild type plants under low light (220 µmol m−2 s−1). Furthermore, CO2 response curves indicated higher in vivo Rubisco activity (Vcmax) in spr2 compared to wild type plants, as well as an enhanced maximum rate of electron transport used in the regeneration of ribulose-1,5-bisphosphate (Jmax). These data indicate that loss of function of FAD7 can enhance the efficiency of both light-dependent and light-independent reactions in photosynthesis. Consistent with this, the spr2 mutant also displayed enhanced growth, with significantly more leaves and a more compact growth habit. In contrast to spr2, another tomato mutant impaired in JA synthesis (acx1) showed no enhancements in growth or photosynthetic efficiency, suggesting that the enhancements observed in spr2 are independent of the effects of this mutation on JA synthesis. These data demonstrate that loss of function of FAD7 can enhance photosynthesis and growth, potentially through its impacts on the chloroplast membranes.

Monitoring of the Surface Ocean Environment Under A Passing Typhoon Using A Wave Glider

Son, Y.B.; Jung, S.-K.; Cho, J. H., and Moh, T, 2020. Monitoring of the surface ocean environment under passing typhoon using a wave glider. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 168–172. Coconut Creek (Florida), ISSN 0749-0208.A wave glider was launched in the south of Jeju, Korea and Typhoon Talim (September 9–18, 2017) passed through the East China Sea (ECS) at the same time. It is used to monitor the effect of Typhoon Talim, which had a low pressure center of 940 hPa and a maximum wind speed of 47 m/s. It made its closest approach to the typhoon around September 16–17. During this time, the atmospheric pressure dropped to 995 hPa, the wind speed was 25 m/s, and the significant wave height was 9.1 m. Satellite images showed two hot spots. One was an upwelling event in the southern part of the ECS and the other was a horizontal movement of the water column in the middle of the ECS. When the typhoon was approaching, the wave glider measured the lowest sea surface temperature and salinity, whereas the chlorophyll levels and turbidity increased, which could not be explained by local observations. However, satellite data could compare the trends before and after the typhoon's approach, where the data indicated that the vertical mixing and upwelling events near the typhoon's center were responsible for the low temperature and high chlorophyll levels in the surface layer.

Evaluating Chlorophyll and Nitrogen Production in Edible Plant Sources Grown Under 5 Gigahertz Radiofrequency Radiation Emissions

By 2022 the demand for constant connectivity to high speed wireless communication networks is predicted to skyrocket with over 12 billion mobile devices and almost half a billion public Wi‐Fi hot spots. Both 5th generation (5G) cellular networks and current IEEE 802.11 Wi‐Fi can transmit radiofrequencies in the 5 Giga Hertz (5 GHz) range. Higher frequencies, such as those in the 5 GHz range, have been shown to be more harmful to humans and biological systems than lower frequencies. Although not well understood, frequencies generated in this range by newly established 5G cellular networks, and common Wi‐Fi 5 GHz networks, may pose a danger to biological systems which could have a significant impact on human health.This work looks to examine the effects of 5 GHz radiofrequency radiation on chlorophyll production and nitrogen levels in green leafy plants, in particular spinach. Chlorophyll is the most important intermediate in the conversion of light to organic matter in photosynthesis. Nitrogen is known to be directly proportional to chlorophyll content and is found in high amounts within enzymes, proteins, and thylakoid membranes required for photosynthesis. Spinach is known to have high levels of chlorophyll and has been chosen as the plant for testing. Using a TYS‐B Portable Chlorophyll Meter, chlorophyll and nitrogen levels will be non‐destructively measured over 5 weeks of growth under close bombardment from 5 GHz generated radio emissions in treatment groups and control groups shielded from all radio frequency emissions.If statistical significance suggests chlorophyll and nitrogen levels are decreased between treatment and control groups, further investigation may be warranted to assess the impact on human and plant health. Lower chlorophyll levels could decrease overall group weight and may contribute to a decline in pollinators. Decreased pollinators and lower crop yields could cost consumers billions of dollars in lower availability. As high frequency radio emissions continue to increase across the globe, any information would be available in determining possible dangers from these new technologies.Support or Funding Information• Bridges to Baccalaureate Grant awarded through National Institute of General Medical Sciences, Coconino Community College NIH Grant # 1R25GM102788‐01

Effects of climate changes on the microbial activities and prokaryotic abundances in the euphotic layer of the Central Mediterranean Sea

Prokaryotic microorganisms are at the base of marine food web and are sensitive to climate changes. In the Mediterranean Sea, an important link between surface water warming and microbial activities is hypothesized to exist on a seasonal and inter-annual scale, with high amounts of organic matter utilized by prokaryotes and recycled in warm periods. To test this hypothesis, from 1998 to 2013, the prokaryotic abundance and microbial activities (enzymatic activities, prokaryotic heterotrophic production, and respiration), together with trophic parameters (chlorophyll, particulate organic carbon, and nitrogen), were measured in the euphotic layer of the Ionian Sea (Central Mediterranean). A statistical simultaneous analysis of the environmental and prokaryotic data was performed with the aim of depicting the evolution of microbial activities and their implications in the biogeochemical cycles. Results showed that despite the large spatial and temporal variability, temperature was the main factor affecting the variability of microbial abundance and metabolism with significant differences on both seasonal and inter-annual scales. Particularly interesting is the increase of production in summer and of the respiration in winter. In spite of low levels of chlorophyll and organic carbon, an increase of prokaryotic heterotrophic production, coupled with that of alkaline phosphatase, was found. As a consequence, the increase of prokaryotic biomass was bottom-up sustained. Most of prokaryotic activities and respiration rates were significantly correlated to organic carbon pools; the process of organic matter decomposition was frequently enhanced at higher temperature, and both prokaryotic production and growth efficiency increased in summer. In view of climate changes, the rise in temperature was associated to the increase of heterotrophic activities and this trend can have a predictive value to describe the microbial processes in the Central Mediterranean Sea.

Morphophysiological variation and metal concentration in the thallus of Parmotrema tinctorum (Despr. ex Nyl.) Hale between urban and forest areas in the subtropical region of Brazil.

Anthropic activities such as the emission of pollutants resulting from industrial and agropastoral activities promote several changes in urban and forest areas. Lichens are organisms that are used in air quality evaluations due to their sensitivity to these changes. The aim of this study is to analyze the presence of morphophysiological damages and the metal concentration in samples of the lichen Parmotrema tinctorum, in urban and forest areas, checking for possible parameter variations between these areas, in the different matrices and seasons in the Southern region of Brazil. Six areas were selected (urban and forest), assigned to the rural/urban and urban/industrial matrices belonging to the watershed of the Rio dos Sinos, Brazil. The following parameters were analyzed: Index of photobiont vitality (IPV), photosynthetic pigments (chlorophyll, carotene, and pheophytin) and metals (Cu, Cr, Zn, Pb, and Ni) in the thallus of the lichen. The data were analyzed by an ANOVA one way, Pearson correlation test, and principal component analysis (PCA). Variations in the morphophysiological parameters were recorded in all the areas revealing significant differences. The lowest IPV values and highest concentration of metals were recorded in the urban environment, while low chlorophyll levels were found in the forest areas. The PCA showed a distinction between the areas and the season. The level of urbanization, vehicle traffic, and the weather conditions might have influenced the results. The use of P. tinctorum, the index of photobiont vitality and chlorophyll and pheophytin content, has proved to be an efficient tool to diagnose the air quality in the areas analyzed, allowing its use as a model in air monitoring studies, both in urban and forest areas, as well as in distinct matrices in the subtropical region.

Leaf age and light quality influence the basal resistance against Botrytis cinerea in strawberry leaves

In this study, the effects of both leaf age and light quality on leaf resistance against Botrytis cinerea were investigated. Strawberry plants were grown in a growth chamber equipped with white, blue, red or red + blue light-emitting diodes (LEDs) at a photosynthetic photon flux (PPF) of 100 μmol m−2 s−1. The effect of leaf age and light quality on leaf morphology, resistance to B. cinerea, hydrogen peroxide levels, metabolites and pigments was studied. Leaf number increased under red light, while leaf petiole length was reduced by red + blue light. Leaf resistance to B. cinerea dramatically increased with leaf age from 1- to 4-week-old leaves but decreased again in 5-week-old leaves. Red light significantly improved leaf resistance, while white and blue-light treated leaves were the most susceptible to B. cinerea at all leaf ages. Hydrogen peroxide levels positively correlated with disease severity and were influenced by both leaf age and light quality. They were lowest in 4-week-old leaves and in red light-grown leaves, irrespective of leaf age. Chlorophyll and carotenoids levels negatively correlated with disease severity and increased with leaf age but were lowest in blue light-grown leaves. Total phenolics and flavonoid levels were very high in the very susceptible 1-week-old leaves and considerably lower in the older leaves. Red light stimulated total phenolics in 1–4-week-old leaves. Proline levels were strongly stimulated by blue light, especially in 1 and 5-week-old leaves. Overall, low hydrogen peroxide levels and high chlorophyll and carotenoids levels appear to be the best indicators for leaf resistance to B. cinerea in strawberry leaves. Moreover, leaf age should be taken into account when assessing the effect of light quality on disease resistance.

Arbuscular mycorrhiza fungi increased the susceptibility of Astragalus adsurgens to powdery mildew caused by Erysiphe pisi

ABSTRACTPowdery mildew caused by Erysiphe pisi is a major factor that affects the growth of standing milkvetch (Astragalus adsurgens). As arbuscular mycorrhizal fungi (AMF) have shown to be enhancing the resistance of plants to biotrophic pathogens such as powdery mildew, a study was carried out to look at the effects of three AMF, either singularly or in combination, on the growth of standing milkvetch and susceptibility to E. pisi. The results showed that the presence of AMF enhanced the growth of standing milkvetch even though their presence in the roots increased susceptibility to this foliage pathogen compared with plants having no AMF. This increase in growth of plants with severe infection of powdery mildew was especially surprising as leaves contained lower levels of chlorophyll than plants without AMF and had a greater concentration of malondialdehyde, an indicator of the damage of cell membrane. The effects on the extent of growth and powdery mildew enhancement differed inconsistently with the type of AMF in roots. The effects on growth and powdery mildew were not related to intensity of AMF colonisation. The peroxidase (POD) was consistently higher activity (15% to 72%) in plants with AMF than plants without them.