Lower Chlorophyll Content Research Articles

Effect of different mulching materials on maize growth and yield in conservation agriculture systems of sub-humid Zimbabwe

The introduction of conservation agriculture (CA) for smallholders increased the competition for crop residues between crop and livestock enterprises of the mixed smallholder farming system. Smallholders practicing CA have resorted to using grass and leaf litter in addition to available crop residues. The effect of these different mulching materials on maize (Zea mays L.) growth and yield is not well documented in smallholder CA systems of southern Africa. A two-year experiment was run in 2012/13 and 2013/14 seasons to evaluate the effect of maize residues, grass (Hyparrhenia filipendula (L.) Stapf.) and leaf litter that farmers are currently using and residues from leguminous species, sunhemp (Crotolaria juncea L.) and Tephrosia (Tephrosia vogelii ((Hook) f.)) on maize nitrogen (N) uptake, growth and yield. Significant differences in soil water content across treatments were only observed during March in 2012/13 season. Maize residues retained more soil water and Tephrosia had the lowest soil water content when seasonal rainfall pattern was erratic. Grass and Tephrosia treatments had the lowest chlorophyll content. Conventional ploughing, maize residues and leaf litter had similar chlorophyll content which was significantly higher than grass and Tephrosia treatments. At a site with higher initial soil fertility conventional ploughing treatment out yielded the other treatments by 727–1265 kg ha−1. With more degraded sandy soil conventional practice had 119–430 kg ha−1 more maize grain than the CA treatments. With adequate fertilization, the mulching materials have a similar effect on maize growth in basins and direct seeding. Further studies on different application rates of mulching materials and mineral N fertilizer, and nutrient release patterns of these residues are critical in order to better understand soil fertility management under smallholder CA systems.

Adjustment of pigment composition in Desmarestia (Desmarestiaceae) species along a sub-Antarctic to Antarctic latitudinal gradient

Photosynthesis at high latitudes demands efficient strategies of light utilization to maintain algal fitness and performance. The fitness, and physiological adaptation, of a plant or algae species depends in part on the abundance and efficiency of the pigments it can produce to utilize the light resource from its environment. We quantified pigment composition and concentration in six species of the brown macroalgal genus Desmarestia, collected from sub-Antarctic sites (Strait of Magellan, Beagle Channel–Cape Horn Province) and sites on the Antarctic Peninsula and adjacent islands. Sub-Antarctic Desmarestia species exhibited lower concentrations of chlorophyll a , chlorophyll c and fucoxanthin than endemic Antarctic species. Antarctic samples of D. menziesii and D. antarctica collected along a decreasing latitudinal gradient showed spatial and interspecific differences in light-harvesting pigment composition. Our results suggest distinct physiological adjustments in Desmarestia species in response to heterogeneous abiotic environmental conditions. The marine sub-Antarctic and Antarctic ecosystems are characterized by harsh environments (e.g., extreme irradiance, photoperiod, temperature, salinity) to which the physiology of macroalgal species must adapt. Keywords: Macroalgae; Phaeophyceae; photosynthesis; physiology; environmental heterogeneity; Chile. (Published: 4 August 2016) Citation: Polar Research 2016, 35 , 29383,http://dx.doi.org/10.3402/polar.v35.29383

Lower leaf gas-exchange and higher photorespiration oftreated wastewater irrigated Citrus trees is modulated bysoil type and climate.

Water quality, soil and climate can interact to limit photosynthesis and to increase photooxidative damage in sensitive plants. This research compared diffusive and non-diffusive limitations to photosynthesis as well as photorespiration of leaves of grapefruit trees in heavy clay and sandy soils having a previous history of treated wastewater (TWW) irrigation for >10 years, with different water qualities [fresh water (FW) vs TWW and sodium amended treated wastewater (TWW + Na)] in two arid climates (summer vs winter) and in orchard and lysimeter experiments. TWW irrigation increased salts (Na(+) and Cl(-) ), membrane leakage, proline and soluble sugar content, and decreased osmotic potentials in leaves of all experiments. Reduced leaf growth and higher stomatal and non-stomatal (i.e. mesophyll) limitations were found in summer and on clay soil for TWW and TWW + Na treatments in comparison to winter, sandy soil and FW irrigation, respectively. Stomatal closure, lower chlorophyll content and altered Rubisco activity are probable causes of higher limitations. On the other hand, non-photochemical quenching, an alternative energy dissipation pathway, was only influenced by water quality, independent of soil type and season. Furthermore, light and CO2 response curves were investigated for other possible causes of higher non-stomatal limitation. A higher proportion of non-cyclic electrons were directed to the O2 dependent pathway, and a higher proportion of electrons were diverted to photorespiration in summer than in winter. In conclusion, both diffusive and non-diffusive limitations contribute to the lower photosynthetic performance of leaves following TWW irrigation, and the response depends on soil type and environmental factors.

Physical and chemical mutagenesis in Stevia rebaudiana: variant generation with higher UGT expression and glycosidic profile but with low photosynthetic capabilities

The leaf explants of Stevia rebaudiana were exposed to a range of EMS (chemical mutagen) and gamma radiation (physical mutagen) doses. Among all the treatments, doses of 0.4 % v/v EMS and 0.95 KR gamma radiation were found to be most effective treatment for selection of variants via direct shoot bud induction. The field-established plants designated as EMS (E), gamma (G), and control (C) plants were subjected to photosynthetic parameter studies where E and G plants showed lower chlorophyll content, transpiration rate, CO2 exchange rate, and stomatal conductance. The implanted field soil at the time of harvesting of plants showed reduction in organic carbon (OC), electrical conductivity (EC), phosphorus (P)/potassium (K), and total Kjeldahl nitrogen (TKN). The ISSR profiling of E, G, and C scored total of 107 bands out of which 63 % were polymorphic bands, and plant E was found to be more distant from the C plant phylogenetically. On phytochemical analysis, the G plant registered twofold enhanced rebaudioside A with lower stevioside (3.2 ± 0.22 % dry wt.) content, whereas E plant showed more than 1.5- and 2.0-fold increase in stevioside and rebaudioside A as compared to control plants. Both the E (3.1 ± 0.15 % dry wt.) and G (2.3 ± 0.21 % dry wt.) plants registered lower steviol. The enhanced steviol glycoside profile was supported by the RT-PCR analysis of UGT74G1 and UGT76G1 that corresponds to stevioside and rebaudioside A biosynthesis, respectively. While the E plant showed 5–6-fold increase in the UGT74G1 (RQ = 5.51 ± 0.5) and UGT76G1 (RQ = 6.61 ± 0.5) gene expression, the G plant showed 5-fold increase in UGT76G1 (RQ = 5.29 ± 0.2) gene expression.

Elimination of Lily Symptomless Virus by In Vitro Scaling and Reinfection Rates under Various Culture Conditions in Korean Native Lilies

Abstract: The lily symptomless virus (LSV) is the most common virus in Korean native lilies and causes various types of dama ge to overall plant growth. This study was carried out to investigate the elimination rate of the LSV by the in vitro scale culture (scaling) method in Korean native lilies and to test reinfection rates of the LSV under several field culture conditions of bul b production. Four Korean native lilies ( Lilium dauricum, L. distichum, L. lancifolium, and L. maximowitzii) were used and their scales were cultured in vitro for micro-scale formation. The micro-scales were subcultured repeatedly using MS culture medium supplemented with 30 or 90 g･L -1 sucrose. The culture conditions were 24 µmol･m -2 ･s -1 PPFD with 16 hour daylength usin g fluorescent lamps and maintained at 22 ± 2°C. The virus-free bulblets were grown for one to three years in the greenhouse and transplanted to the field in October or March. Virus infection rates were investigated by direct tissue blotting immunobind ing assays and measurement of chlorophyll and protein contents. Virus-free plants could be obtained from the 5th subculture of micro-scales in L. lancifolium and L. maximowitzii or from primary culture in L. dauricum and L. distichum. LSV-free plants were reinfected during bulb production in the field. Reinfection rates were higher at older bulb ages and under higher planting dens ity. The plants planted in October and at inland Gyeongsan had higher infection rates than those planted in March and at coastal area Pohang. The reinfection rate of L. maximowitzii was higher than those of L. dauricum and L. lancifolium. The LSV-infected plants had lower chlorophyll contents and unchanged protein contents compared to virus-free plants.Additional key words:

Características físico-químicas de cebolinhas comum e europeia

Resumo A cebolinha é uma folhosa bastante utilizada como condimento no Brasil, onde as espécies popularmente conhecidas como comum e europeia são as mais utilizadas. Objetivou-se com este trabalho avaliar a qualidade físico-química de cebolinhasAllium fistulosum (comum) e Allium schoenoprasum (europeia). As amostras das diferentes espécies foram analisadas quanto a: coloração (luminosidade, ângulo hue e cromaticidade); sólidos solúveis (SS); acidez titulável (AT); relação SS/AT; pH; umidade; clorofila a; clorofila b; clorofila total e carotenoides totais. Com relação aos parâmetros de cor, as espécies mostraram resultados muito próximos, evidenciando coloração característica de cebolinha, expressa pela cor verde com tendência ao amarelo. Também em relação ao pH observou-se semelhanças, enquadrando-se na faixa de baixa acidez. Já para SS e acidez, a variedade europeia apresentou maiores teores. Encontrou-se também proximidade de valores para os pigmentos avaliados, sendo a proporção de clorofila a em relação à b em média de 2,3:1. Os resultados físico-químicos mostraram semelhanças entre as espécies, sendo observados baixa acidez, elevado conteúdo de umidade e de clorofila, além de razoáveis teores de sólidos solúveis e carotenoides. Essas informações sobre cebolinhas verdes cultivadas no Brasil, ainda escassas na literatura, vêm a contribuir com a produção de dados sobre essa hortaliça, podendo motivar seu consumo e a expansão de sua comercialização em formas diversificadas.

Experiments in optimizing simulations of the subsurface chlorophyll maximum in the South China Sea

The subsurface chlorophyll maximum (SCM) is widespread in the oligotrophic ocean and significantly contributes to primary production. One reason for the SCM formation is believed to be the rapid export of phytoplankton from surface layers, which might be caused by aggregation, faster sinking rates under nutrient limitation, or the formation of a resting stage. In this study, these three processes were included in a biological model to investigate their contributions to subsurface chlorophyll. To further identify their individual effects on SCM formation, four modeling experiments were carried out. Three used a simple approach with either (a) density-dependent aggregation, (b) accelerated sinking rate of phytoplankton, or (c) a resting stage. The other experiment combined all three approaches (a–c). A set of observations in the South China Sea was used to optimize the four experiments and compare their abilities to replicate observed values. The results of the experiments with the resting stage showed the best fit to the field observations. All experiments were able to capture major features of the chlorophyll field (e.g. surface bloom and SCM). The experiment with accelerated sinking rate failed to reproduce the observed profile of particulate organic carbon. The experiment with only aggregation predicted lower chlorophyll concentrations in summer than those measured in the field, while experiments with the resting stage reproduced more accurate chlorophyll concentrations. Formulas including the resting stage more successfully captured the timing of phytoplankton export than did those including aggregation and accelerated sinking rate. The processes of aggregation and accelerated sinking rate made small contributions to the SCM formation in the last experiment. Overall, these results show that introducing the resting stage improves SCM simulations of the South China Sea. The results of the experiment with only the resting stage showed that the resting cells shift rapidly from the surface water, encounter better nutrient conditions in nutricline layers, partially germinate into vegetative cells, become shade-adapted, and increase subsurface chlorophyll concentrations during summer, which contributes to SCM formation.

Physiological and biochemical responses of roadside trees grown under different urban environmental conditions in Seoul

The present study revealed that Ginkgo biloba and Platanus occidentalis, the most abundant roadside trees in Seoul, grown under polluted environmental conditions, displayed lower contents of total chlorophyll (Chl), carotenoids (Car), and ascorbic acid (AsA) compared to the trees grown under clean conditions. The reduction in Chl, Car, and AsA contents was 59, 53, and 50%, respectively, in G. biloba, contrary to 26, 23, and 24%, respectively, in P. occidentalis. Furthermore, relative ion leakage and leaf temperature was higher in the trees grown under polluted conditions than in those grown under clean conditions. The increase in relative ion leakage and leaf temperature was 58 and 3% for G. biloba and 17 and 4% for P. occidentalis, respectively. Our results, therefore, highlighted the negative impact of urban environmental pollution on the physiological and biochemical parameters in roadside trees.

Variability in foraging behaviour of red-footed boobies nesting on Europa Island

Seabirds are considered to be good indicators of the marine environment. However, little is known about the effects of environmental variability on the foraging behaviour of tropical seabirds. Red-footed boobies (RFB) nesting on Europa Island (Mozambique Channel) were fitted with GPS devices over four years and different breeding stages. We first show that the durations of foraging trips vary extensively according to the stage of the breeding, being short during brooding, intermediate during incubation and long during fledging. This result highlights the importance of considering breeding stage when conducting comparisons of foraging between sites or years. In addition, we show that RFB adjusted their foraging behaviour between years (2003, 2011, 2012 and 2013) according to the prevailing environmental conditions. During 2011, RFB made longer foraging trips with larger area-restricted search (ARS) zones over a larger total surface area, suggesting that the foraging conditions were probably poor. This year was characterized by a decrease of the major environmental drivers of the Mozambique Channel system, i.e. particularly low chlorophyll concentrations in the northern part of the Mozambique Channel, as well as a weak eddy activity. This observation suggests that environmental conditions may have altered the southward transport and concentration processes structuring the trophic chain, leading to adverse conditions for a central-place forager like the RFB. Our results emphasize that environmental and breeding stage variation should be taken into account to better understand the distribution of these predators in marine tropical ecosystems.

Disruption and Wet Extraction of the Microalgae Chlorella vulgaris Using Room-Temperature Ionic Liquids

Recently, ionic liquids have been demonstrated to increase the efficiency of solvent extraction of lipids from microalgae. However, to date, mostly imidazolium-based ionic liquids have been investigated. This report extends the range of cations studied to over 30, including imidazolium, ammonium, phosphonium, and pyridinium derivatives, which were screened for their ability to increase hexane extraction efficiency of lipids from freeze-dried microalgae Chlorella vulgaris at ambient temperature. Promising ionic liquids were first identified using gravimetric analysis of total extractable oils. Oils extracted after ionic liquid pretreatment were further characterized with respect to fatty acid methyl ester (FAME) equal to biodiesel yield, FAME composition, and chlorophyll content. With few exceptions, all of the tested ionic liquids had lower chlorophyll content than standard solvent extraction techniques. The effect of process parameters such as mass ratio of algae to ionic liquid, incubation time, water c...

Longitudinal Plankton Dynamics in the Rivers Rhine and Elbe

We compared the longitudinal plankton development in the two large rivers Rhine and Elbe by means of four Lagrangian sampling campaigns performed within the time span 2009–2011. The campaigns revealed low chlorophyll concentrations in the Rhine along a long river stretch (Rhine-km 170 to 854) with maximum values below 5 µg L−1 in 2010. In contrast, the Elbe (Elbe-km 4 to 582) showed high and longitudinally increasing chlorophyll concentrations with maximal values of 174 µg L−1 in 2009 and 123 µg L−1 in 2011. Additional samples of the benthic bivalves along the river stretches revealed high densities of the filter feeders in the Rhine that could potentially explain losses of plankton production. Their densities in the Elbe were significantly lower, making important losses to benthic filter feeders unlikely. However, strong phytoplankton growth was observed during the sampling campaign in 2011 in the Rhine coinciding with a low discharge event. This resulted in an exceptionally high chlorophyll value of up to 244 µg L−1 in the lower river sections, a value that was not reached in the last two decades of continuous water quality monitoring in the Rhine. Even though we cannot fully explain this phenomenon, it shows that phytoplankton has a high growth potential in the Rhine but is usually controlled by other mechanisms. Tributaries represented an additional and important source of plankton biomass and suspended substances in the Rhine, whereas they primarily diluted the plankton concentrations in the Elbe. Copyright © 2015 John Wiley & Sons, Ltd.

English

To investigate the formation of the yellow-green leaf color of burley tobacco, the inheritance of leaf color, the contents of plastid pigments and the characteristics of chlorophyll metabolism in burley tobacco leaves were determined with burley tobacco cv. Burley21 and normal green Maryland tobacco cv. Maryland609 as the experimental plants. Field genetic populations of the reciprocal F1 generation, inbred F2 generation and the backcrossed BC1 generation of Burley21 and Maryland609 were constructed and the statistical analysis revealed that the inheritance of the yellow-green leaf color of burley tobacco was controlled by a double recessive gene. Chlorophyll content and carotenoid content were measured using spectrophotometric method and the results found that chlorophyll contents in the leaves of Burley21 were always lower than in that of Maryland609 during the whole growth period; the content ratios of chlorophyll to carotenoid showed a decreasing trend in Burley21, while in normal green Maryland609, it maintained at about 5. Further researches on the characteristics of chlorophyll metabolism indicated that the precursors of δ-aminolevulinic acid (ALA), porphobilinogen (PBG), uroporphyrinogen III (Urogen III), coproporphyrinogen III (Coprogen III), protoporphyrin IX (Proto IX), Mg-protoporphyrin IX (Mg-Proto IX) and protochlorophyllide (Pchlide) in chlorophyll biosynthesis in Burley21 were lower than in Maryland609 at vigorous growing period; the activity of δ-aminolevulinate dehydratase (ALAD) in Burley21 was 0.43% as compared to Maryland609, but the activity of chlorophyllase in Burley21 was 2.04 times as high as in that of Maryland609. In conclusion, the yellow-green leaf color of burley tobacco was caused by low chlorophyll content, which might due to the combination of inhibited biosynthesis and accelerated degradation of chlorophyll regulated by key enzymes of ALAD and chlorophyllase, respectively. © 2016 Friends Science Publishers

The effect of ice phenology exerted on submerged macrophytes through physicochemical parameters and the phytoplankton abundance

<p>The physicochemical parameters of water, the concentration of chlorophyll-<em>a</em> and the submerged aquatic vegetation (SAV) were studied to evaluate the effects of different winter seasons on the biomass of macrophytes in shallow eutrophic lakes. We hypothesised that a lack of ice cover or early ice-out can influence the physicochemical parameters of water and thus change the conditions for the development of phytoplankton and SAV. The studies were conducted in four lakes of the Western Polesie region in mid-eastern Poland after mild winters with early ice-out (MW, 2011 and 2014) and after cold winters with late ice-out (CW, 2010, 2012 and 2013). The concentrations of soluble and total nitrogen, chlorophyll-<em>a</em> and the TN:TP ratio in the lakes were considerably higher, whereas the concentration of soluble and total phosphorus and water transparency were significantly lower after the MW compared with after the CW. No differences were found in water temperature, reaction and electrolytic conductivity. Low water turbidity linked with low concentration of chlorophyll-<em>a</em> after the CW resulted in increased water transparency and the total biomass of the SAV. The negative effect of the MW on the macrophyte species was stronger on more sensitive species (<em>Myriophyllum spicatum</em>,<em> Stratiotes aloides</em>) compared with shade tolerant <em>Ceratophyllum demersum</em>. Our findings show that the ice cover phenology affected by climate warming can change the balance between phytoplankton and benthic vegetation in shallow eutrophic lakes, acting as a shift between clear and turbid water states. We speculate that various responses of macrophyte species to changes in the water quality after two winter seasons (CW and MW) could cause alterations in the vegetation biomass, particularly the expansion of shade tolerance and the decline of light-demanding species after a series of mild winters.</p>

Quantifying mangrove chlorophyll from high spatial resolution imagery

Lower than expected chlorophyll concentration of a plant can directly limit photosynthetic activity, and resultant primary production. Low chlorophyll concentration may also indicate plant physiological stress. Compared to other terrestrial vegetation, mangrove chlorophyll variations are poorly understood. This study quantifies the spatial distribution of mangrove canopy chlorophyll variation using remotely sensed data and field samples over the Rapid Creek mangrove forest in Darwin, Australia. Mangrove leaf samples were collected and analyzed for chlorophyll content in the laboratory. Once the leaf area index (LAI) of sampled trees was estimated using the digital cover photography method, the canopy chlorophyll contents were calculated. Then, the nonlinear random forests regression algorithm was used to describe the relationship between canopy chlorophyll content and remotely sensed data (WorldView-2 satellite image bands and their spectral transformations), and to estimate the spatial distribution of canopy chlorophyll variation. The imagery was evaluated at full 2m spatial resolution, as well as at decreased resampled resolutions of 5m and 10m. The root mean squared errors with validation samples were 0.82, 0.64 and 0.65g/m2 for maps at 2m, 5m and 10m spatial resolution respectively. The correlation coefficient was analyzed for the relationship between measured and predicted chlorophyll values. The highest correlation: 0.71 was observed at 5m spatial resolution (R2=0.5). We therefore concluded that estimating mangrove chlorophyll content from remotely sensed data is possible using red, red-edge, NIR1 and NIR2 bands and their spectral transformations as predictors at 5m spatial resolution.

Characterization and mapping of a novel light-dependent lesion mimic mutant lmm6 in rice (Oryza sativa L.)

A novel rice lesion mimic mutant (LMM) was isolated from an ethane methyl sulfonate (EMS)-induced 02428 mutant bank. The mutant, tentatively designated as lmm6, develops necrotic lesions in the whole growth period along with changes in several important agronomic traits. We found that the initiation of the lesions was induced by light and cell death occurred in lmm6 accompanied with accumulation of reactive oxygen species (ROS). The lower chlorophyll content, soluble protein content and superoxide dismutase (SOD) activity, the higher malondialdehyde (MDA) content were detected in lmm6 than in the wild type (WT). Moreover, the observation by transmission electronic microscope (TEM) demonstrated that some organelles were damaged and the stroma lamella of chloroplast was irregular and loose in mesophyll cell of lmm6. In addition, lmm6 was more resistant than WT to rice blast fungus Magnaporthe grisea infection, which was consistent with increased expression of four genes involved in the defense-related reaction. Genetic analysis showed that mutant trait of lmm6 is inherited as a monogenic recessive nuclear gene located on the long arm of chromosome 6. Using simple sequence repeat (SSR) markers, the target gene was finally delimited to an interval of 80.8 kb between markers MM2359 and MM2370, containing 7 annotated genes. Taken together, our results provide the information to identify a new gene involved in rice lesion mimic, which will be helpful in clarifying the mechanism of cell death and disease resistance in rice.

Determinação da maturidade fisiológica de sementes de pimenta dedo de moça Capsicum baccatum var. pendulum

Um aspecto ainda pouco estudado, mas de grande relevância no processo produtivo de sementes de pimenta do tipo dedo de moça (Capsicum baccatum var. pendulum) é a determinação tanto da maturidade fisiológica quanto do momento mais adequado para a colheita. Neste contexto, o objetivo deste trabalho foi avaliar a qualidade fisiológica de sementes de pimenta da espécie C. baccatum var. pendulum obtidas de frutos em diferentes estádios de maturação. O experimento foi realizado nas instalações do campo experimental e laboratórios de sementes e de pós-colheita da Embrapa Hortaliças, Brasília-DF. Para a determinação da maturidade fisiológica foi utilizada a cultivar BRS Mari. As sementes foram obtidas de frutos colhidos em diferentes estádios de maturação (20, 30, 40, 50, 60, 70 e 80 dias após antese). Foram determinados a coloração dos frutos, comprimento longitudinal, teor de clorofila e de capsaicina. Nas sementes, foram determinados o teor de água, a massa de 100 sementes, a germinação, a emergência de plântulas em casa de vegetação e o vigor, estimado pela primeira contagem de germinação e teste de envelhecimento acelerado. Foi utilizado o delineamento inteiramente casualizado. A maturidade fisiológica das sementes ocorreu aos 70 dias após a antese, onde os frutos apresentavam coloração vermelha, teores mínimos de clorofila e maiores picos de capsaicina. Neste estádio, as sementes apresentam valores máximos de germinação, vigor e matéria seca e teor de água de 39%.

Effects of Shrub Islands Created by Rhodomyrtus tomentosa (Aiton) Hassk. on the Growth, Chlorophyll Fluorescence, and Chloroplast ultrastructure of Pine Seedlings in Degraded Land of South China

AbstractIn degraded land of South China, the shrub Rhodomyrtus tomentosa (Aiton) Hassk. grows in aggregations and creates “shrub islands” with increased soil porosity and soil moisture but reduced soil nutrient content and light penetration. Previous researches indicated that these shrub islands can facilitate establishment of broad‐leaved tree seedlings. Because conifers are commonly used in reforestation projects, we determined whether shrub islands created by R. tomentosa also facilitate coniferous seedlings. Two common conifers, the native Pinus massoniana and the exotic Pinus elliottii, were transplanted on shrub islands and in open spaces (controls) between islands, and their growth, chlorophyll fluorescence, and chloroplast ultrastructure were investigated. Neither of the pine species was facilitated by the shrub islands. P. elliottii grew obviously higher in the open than under the R. tomentosa canopy, while P. massoniana was not facilitated by shrub islands, but it was not hindered either. The reduced growth of P. elliottii on shrub islands was associated with dilation of thylakoids in chloroplasts of mesophyll cells, lowered chlorophyll content, and reduced electron transport rate values. The results of this study indicate that P. elliottii should be transplanted in open spaces, and P. massoniana can be transplanted in open spaces or on shrub islands as part of restoration efforts, and the restoration technology of shrub island should be carefully used in degraded land of South China according to the species identity. Copyright © 2015 John Wiley & Sons, Ltd.

Overexpression of the iron transporter NtPIC1 in tobacco mediates tolerance to cadmium.

Overexpression of the iron transporter NtPIC1 increases iron concentration in shoots and reduces Cd uptake/accumulation in plants, mediating tolerance to cadmium. Cadmium (Cd) is toxic to plant cells and causes plants to display a typical iron (Fe) deficiency phenotype. NtPIC1 (Permease In Chloroplast1) is an Fe transporter protein in tobacco, required for Fe homeostasis. Based on preliminary results in transformed Saccharomyces cerevisiae BY4741 cells, which showed that NtPIC1 expression increased Cd tolerance, this study evaluated Cd tolerance in tobacco plants overexpressing NtPIC1 (NtPIC1-OE). We show that these plants have longer roots and higher fresh weights than wild-type (WT) plants after Cd exposure. Under Cd stress, WT plants display more chlorosis, stronger growth inhibition, and lower chlorophyll concentrations than NtPIC1-OE plants. Importantly, NtPIC1-OE plants had higher Fe concentrations in shoots and lower Fe concentrations in roots, and Cd concentrations in NtPIC1-OE plants were significantly lower compared to those in WT plants. Moreover, Fe transport-related genes (NtPIC1, NtNRAMP1, and NtFER1) were upregulated in NtPIC1-OE plants, while Fe deficiency-related genes (NtFRO1, NtIRT1, and NtZIP1) that mediate Cd uptake were downregulated. We also found that the activities of several antioxidative enzymes were significantly higher in NtPIC1-OE plants than in WT plants under Cd stress. Overall, our results demonstrate that overexpression of NtPIC1 is an efficient way to increase shoot Fe concentrations and reduce Cd uptake/accumulation in plants.

Dissection of drought response of modern and underutilized wheat varieties according to Passioura's yield-water framework.

Trait-based breeding is essential to improve wheat yield, particularly when stress adaptation is targeted. A set of modern and underutilized wheat genotypes was examined in a 2-year field experiment with distinct seasonal water supply. Yield formation and drought response strategies were analyzed in relation to components of Passioura's yield-water framework based on phenological, morphological, physiological, and root characteristics. Limited water supply resulted in 60% yield loss and substantially lower water use (37%), water use efficiency (32.6%), and harvest index (14%). Phenology and root length density were key determinants of water use. Late flowering underutilized wheat species with large root system and swift ground coverage showed greatest water use. Leaf chlorophyll concentration and stomata conductance were higher in modern cultivars, supporting their high biomass growth and superior water use efficiency. While, lower chlorophyll concentration and stomata conductance of underutilized wheats indicated a water saving strategy with an intrinsic limitation of potential growth. Harvest index was strongly dependent on phenology and yield components. Optimized flowering time, reduced tillering, and strong grain sink of modern cultivars explained higher harvest index compared to underutilized wheats. Cluster analysis revealed the consistent differentiation of underutilized and modern wheats based on traits underlying Passioura's yield-water framework. We identified physiological and root traits within modern cultivars to be targeted for trait-based crop improvement under water-limited conditions. High capacity of water use in underutilized genetic resources is related to yield-limiting phenological and morphological traits, constraining their potential role for better drought resistance. Still some genetic resources provide adaptive features for stress resistance compatible with high yield as revealed by high harvest index under drought of Khorasan wheat.

Variation in trace element mobility and nitrogen metabolism of Verbascum olympicum Boiss. under copper stress

The aim of this study was to evaluate the effects of copper (Cu) stress on accumulation and transport of trace elements, nitrogen assimilation, and growth parameters of Verbascum olympicum. Eight-week-old seedlings were grown in Hoagland's solution and exposed to 0, 50, 250, or 500 µM CuSO4 for seven days in laboratory conditions. Bioaccumulation of trace elements (boron, bismuth, cobalt, Cu, iron, lithium, manganese, molybdenum, nickel, lead, zinc) in the roots and leaves was determined by inductively coupled plasma–mass spectrometry after one, three, and seven days. Chlorophyll content, nitrate reductase, and glutamine synthetase activities, soluble protein content, and biomass were determined. Copper accumulated in the roots and leaves (up to 19609.8 and 256.2 mg kg−1 dry weight, respectively). Other trace elements accumulated to higher levels in the roots of Cu-treated plants compared with those of control plants. High Cu concentrations decreased nitrogen-assimilatory enzyme activities. Compared with control plants, those treated with high Cu concentrations showed lower chlorophyll contents, total protein contents, and biomass. Nitrogen assimilation and growth parameters of V. olympicum were negatively affected by Cu treatment but mineral nutrition was not severely disrupted. The results support the suitability of V. olympicum as a candidate for phytoremediation of Cu-contaminated soils.