Composition Of Plant Tissues Research Articles

Technosol as an integrated management tool for turning urban and coal mining waste into a resource

The present study aims to evaluate plant growth and chemical characteristics of technosols produced from fine coal waste and an organic compost from urban waste. This could be an alternative method for current disposal practices and a way to promote vegetation cover of mined lands. The experiment was conducted in 2 L containers filled with different substrates conditions: (I) exclusively coal waste, (II) coal waste + 2.5% organic matter, (III) coal waste + 5.0% organic matter, and (iv) agricultural soil as control. All substrates were performed in triplicate, with and without Alfalfa (Medicago sativa) planting. Plant growth was monitored for biomass production and plant tissue composition. Soils were evaluated in terms of fertility, acid generation potential, and sulfur speciation. The substrate composed exclusively of coal waste had almost no plant growth. However, the addition of compost allowed equivalent (with 2.5% organic matter) or even superior (with 5.0% organic matter) plant growth in terms of dry matter compared to the agricultural soil. At both levels of organic matter, soil fertility parameters were appropriate for Alfalfa growth. Regarding the plant tissue, the elemental composition of the shoots was considered adequate for cattle nutrition. Also, there was a reduction of both pyrite content and acid generation potential of the substrates after plant growth. In relation to urban waste, it is estimated that each hectare of technosol (condition III) could utilize around 550 t of organic compost. Thereby, this study addresses the possibility of improving waste management in both mining and urban contexts consistent with circular economy concepts.

Allometries in Plants as Drivers of Forage Nutritive Value: A Review

The nutritive value of forage for herbivores has been for a long time determined by the concentration in protein and, hence in nitrogen (N), the concentration in different minerals (P, K, Ca, Mg, and oligo-elements), and the in vivo dry matter (DM) digestibility. Forage DM digestibility, the proportion of ingested DM being metabolized by ruminant animals has been related to different components of plant tissue composition such as Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF); the NDF concentration represents an estimate of cell wall content while the ADF concentration is an estimate of the more lignified cell wall content. Forage nutritive value is generally analyzed by relating the attributes of nutritive value to plant phenology, in order to predict the decline of these attributes with plant age. A more functional approach, initially developed for the analysis of N concentration dynamic analysis (Lemaire et al. 2008 and Lemaire et al. 2019), and extended for digestibility for this review, is based on the assumption that above-ground plant mass (W) is composed of two compartments: (i) the metabolic compartment (Wm), associated with plant growth process scaling with leaf area, having a high N concentration (%N), and a high Digestibility (%D); (ii) the structural compartment (Ws) associated with architectural plant development, scaling with plant height and thickness and having low %N and %D. With the postulate that Wm is allometrically related to W (Wm = c × Wα with α < 1), the ontogenetic decline of both %N and %D as the plant gets bigger and forage mass increases can be explained, and the purely empirical statistical approach of forage quality based on plant phenology can be replaced by a more mechanistic and comprehensive analysis linking forage production and forage quality dynamics within the same functional approach for a better understanding of genotype-environment-management interactions.

Molybdate toxicity in Chinese cabbage is not the direct consequence of changes in sulphur metabolism.

In polluted areas, plants may be exposed to supra‐optimal levels of the micronutrient molybdenum. The physiological basis of molybdenum phytotoxicity is poorly understood. Plants take up molybdenum as molybdate, which is a structural analogue of sulphate. Therefore, it is presumed that elevated molybdate concentrations may hamper the uptake and subsequent metabolism of sulphate, which may induce sulphur deficiency.In the current research, Chinese cabbage (Brassica pekinensis) seedlings were exposed to 50, 100, 150 and 200 μm Na2MoO4 for 9 days.Leaf chlorosis and a decreased plant growth occurred at concentrations ≥100 μm. Root growth was more affected than shoot growth. At ≥100 μm Na2MoO4, the sulphate uptake rate and capacity were increased, although only when expressed on a root fresh weight basis. When expressed on a whole plant fresh weight basis, which corrects for the impact of molybdate on the shoot‐to‐root ratio, the sulphate uptake rate and capacity remained unaffected. Molybdate concentrations ≥100 μm altered the mineral nutrient composition of plant tissues, although the levels of sulphur metabolites (sulphate, water‐soluble non‐protein thiols and total sulphur) were not altered. Moreover, the levels of nitrogen metabolites (nitrate, amino acids, proteins and total nitrogen), which are generally strongly affected by sulphate deprivation, were not affected. The root water‐soluble non‐protein thiol content was increased, and the tissue nitrate levels decreased, only at 200 μm Na2MoO4.Evidently, molybdenum toxicity in Chinese cabbage was not due to the direct interference of molybdate with the uptake and subsequent metabolism of sulphate.

Growth Analysis and Nutrient Solution Management of a Soil-Less Tomato Crop in a Mediterranean Environment

The data contained in this article are strictly related to our previous article titled “A Targeted Management of the Nutrient Solution in a Soilless Tomato Crop According to Plant Needs” (Signore, A. et al. 2016). The detailed datasets regards the amount of dry matter (Table 1), the nutrient solution consumption (Table 2) and the mineral composition of plant tissues (Tables 3–7) in a soil-less tomato crop. The information contained in this article are necessary since, unlike the northern European countries, such data are generally missing for the crops in the Mediterranean environment. By correlating the parameters reported above, we were able to provide a more precise management of the nutrient solution, by providing the correct nutrient concentration into the nutrient solution in function of (i) the volume of water absorbed, (ii) the growth rate and (iii) the nutrient concentration in tomato plant. Finally, the more precise management of the nutrient solution allowed discharging a lesser amount of water and nutrients into the environment, improving the sustainability of the crop.

Mineral composition of plants Salvia verticillata L. and Salvia patens Cav.

Purpose. The purpose of the study was to investigate mineral composition of new varieties of plants Salvia verticillata L. ‘Musketeer’ and S. patens Сav. ‘Maestro’ selected by Gryshko National Botanical Gardens of NAS of Ukraine in order to determine the suitability of their use in the food and pharmaceutical industries of Ukraine. Methods. X-ray fluorescence method was applied for determining the elemental composition of plant tissues. Results. Mineral elements content in the soil, grass and roots of plants S. verticillata L. and S. patens Сav., are given in the phases of regrowth, budding and flowering. Ability to accumulate elements in the soil, grass and roots was presented. It was established that the aboveground part of the plants contains all 5 of the most important elements in the plants – K, Fe, Cu, Zn and Mn. The rather high content of mesoelements Ca and S were determined. Plants need them in more significant amounts than trace elements. The toxic and potentially toxic elements Pb, Sr and Zr were determined in plants. It has been revealed that despite the high concentration of Si in the soil, this element gets into the plants in insignificant quantities. Other elements on the contrary were accumulated in grass (Mn, K, Sr). The dynamics of elements accumulation and distribution in the soil-roots-grass system (Fe, Pb, Na, P, Al, Mg, Cu) were demonstrated. In the leaves of S. verticillata elements were determined and arranged according to the gradient of accumulation in the following order: K>Ca>Si>Mg>Fe>P>Na>Al>Zn>Mn>Cu, and in S. pa­tens – K>Si>Ca>Mg>P>Fe>Na>Al>Zn>Mn>Sr>Cu. The content of technogenic elements of Zn and Pb in the plants was determined within the limits of the MPC requirements for plant raw materials and food. Conclusion. For the first time in the conditions of introduction in the Right-Bank Forest-Steppe of Ukraine, for the varieties of species S. verticillata and S. patens, the content of macro- and microelements was determined, which are directly related to biologically active compounds. The features of their cumulativeness du­ring transportation in the system soil-roots-leaves, as well as the dependence of their content on the phase of plant development, were clarified. Trace elements Pb, Ni, Mo, Co, Cd, As and Hg were found in insignificant amounts harmless to the human body. The obtained results can be used in the chemotaxonomy of the genus Salvia, in assessing and comparing the quality of fresh and dry sage plant raw materials, further studying the pharmacological properties of these plants and use of them in medicine and food industry. The obtained data have of both scientific and practical importance for the selection of economically valuable species, in the breeding of new varieties and enrichment of the flora of Ukraine.

Identification of Plant Compounds Involved in the Microbe-Plant Communication During the Coinoculation of Soybean with Bradyrhizobium elkanii and Delftia sp. strain JD2.

Delftia sp. strain JD2 is a betaproteobacterium characterized as a plant growth-promoting bacterium with a 'helper' function, enhancing the performance of rhizobial inoculant strains during the coinoculation of alfalfa and clover. In this work we analyzed i) the effect of the coinoculation with Bradyrhizobium elkanii and Delftia sp. strain JD2 strains on the performance of soybean plants and ii) the production of a few secondary plant metabolites that would explain the positive effect of coinoculation on the growth and development of soybean plants. The results showed a beneficial effect of coinoculation on soybean growth, nodulation rate, and pulse yield, with the concomitant benefit for the agricultural economy. In addition, based on a metabolomics approach, we demonstrated that a different pattern of plant metabolites is being produced at different stages of plant growth. The new information suggests that the coinoculation of soybean changes the primary and secondary metabolism of the plant, including changes in the metabolic status of main and secondary nodules within the plant. The relevance of producing a different pattern of photosynthetic and photoprotective pigments, flavonoids, organic acids, and carbohydrates are discussed. Finally, we propose that JD2 could be used together with bradyrhizobia to manipulate the chemical composition of plant tissues, promoting the nutritional benefits and health of soybean.

Multivariate unmixing approaches on Raman images of plant cell walls: new insights or overinterpretation of results?

BackgroundPlant cell walls are nanocomposites based on cellulose microfibrils embedded in a matrix of polysaccharides and aromatic polymers. They are optimized for different functions (e.g. mechanical stability) by changing cell form, cell wall thickness and composition. To reveal the composition of plant tissues in a non-destructive way on the microscale, Raman imaging has become an important tool. Thousands of Raman spectra are acquired, each one being a spatially resolved molecular fingerprint of the plant cell wall. Nevertheless, due to the multicomponent nature of plant cell walls, many bands are overlapping and classical band integration approaches often not suitable for imaging. Multivariate data analysing approaches have a high potential as the whole wavenumber region of all thousands of spectra is analysed at once.ResultsThree multivariate unmixing algorithms, vertex component analysis, non-negative matrix factorization and multivariate curve resolution–alternating least squares were applied to find the purest components within datasets acquired from micro-sections of spruce wood and Arabidopsis. With all three approaches different cell wall layers (including tiny S1 and S3 with 0.09–0.14 µm thickness) and cell contents were distinguished and endmember spectra with a good signal to noise ratio extracted. Baseline correction influences the results obtained in all methods as well as the way in which algorithm extracts components, i.e. prioritizing the extraction of positive endmembers by sequential orthogonal projections in VCA or performing a simultaneous extraction of non-negative components aiming at explaining the maximum variance in NMF and MCR-ALS. Other constraints applied (e.g. closure in VCA) or a previous principal component analysis filtering step in MCR-ALS also contribute to the differences obtained.ConclusionsVCA is recommended as a good preliminary approach, since it is fast, does not require setting many input parameters and the endmember spectra result in good approximations of the raw data. Yet the endmember spectra are more correlated and mixed than those retrieved by NMF and MCR-ALS methods. The latter two give the best model statistics (with lower lack of fit in the models), but care has to be taken about overestimating the rank as it can lead to artificial shapes due to peak splitting or inverted bands.

Raman Imaging of Plant Cell Walls in Sections of Cucumis sativus.

Raman microspectra combine information on chemical composition of plant tissues with spatial information. The contributions from the building blocks of the cell walls in the Raman spectra of plant tissues can vary in the microscopic sub-structures of the tissue. Here, we discuss the analysis of 55 Raman maps of root, stem, and leaf tissues of Cucumis sativus, using different spectral contributions from cellulose and lignin in both univariate and multivariate imaging methods. Imaging based on hierarchical cluster analysis (HCA) and principal component analysis (PCA) indicates different substructures in the xylem cell walls of the different tissues. Using specific signals from the cell wall spectra, analysis of the whole set of different tissue sections based on the Raman images reveals differences in xylem tissue morphology. Due to the specifics of excitation of the Raman spectra in the visible wavelength range (532 nm), which is, e.g., in resonance with carotenoid species, effects of photobleaching and the possibility of exploiting depletion difference spectra for molecular characterization in Raman imaging of plants are discussed. The reported results provide both, specific information on the molecular composition of cucumber tissue Raman spectra, and general directions for future imaging studies in plant tissues.

Shrub-encroachment induced alterations in input chemistry and soil microbial community affect topsoil organic carbon in an Inner Mongolian grassland

Shrub encroachment frequently occurs in arid and semi-arid grasslands worldwide and affects the regional carbon balance. Many previous studies have revealed the effects of shrub encroachment on bulk carbon content of grasslands, but molecular evidence is surprisingly lacking. In this study, we examined the chemical composition of plant tissues and soil organic carbon (SOC), and soil microbial communities to identify the effects of shrub (Caragana microphylla) encroachment on SOC storage in the top layer (0–10 cm) along a gradient of natural shrub cover in the grasslands of Inner Mongolia. We found that SOC in the shrub patches was derived mainly from leaves, whereas SOC in the grassy matrix was composed of a mixture of fresh root- and leaf-derived compounds. Compared with pure grassland, the SOC decreased by 29% in the shrub-encroached grasslands (SEGs), and this decrease was enhanced by increasing shrub cover. We also found that free lipids and lignin-derived phenols increased while the ratios of ω-C18/∑C18 and suberin/cutin decreased with increasing shrub cover. In addition, the ratios of fungal to bacterial phospholipid fatty acids (PLFAs) and gram-negative to gram-positive bacterial PLFAs decreased with increasing shrub cover. These results indicate that the encroachment of nitrogen-rich legume shrubs can lead to carbon loss by altering the chemical composition of plant inputs as well as the soil microbial community in grassland ecosystems.

Insights from “The Hidden Half”: The impact of root-zone oxygen and redox dynamics on the response of avocado to long-term irrigation with treated wastewater in clayey soil

Treated wastewater (TWW) is a major source of water for agriculture in Israel; however, recent reports indicate a marked yield loss in TWW-irrigated avocado and citrus orchards planted in clayey soils. The association of the yield loss with clayey soils rather than sandy soils suggests that it is associated with conditions in the root zone, and specifically poor aeration. A three-year study (2012–2015) was conducted in an avocado orchard planted in clayey soil, comparing the oxygen and redox conditions in the root zone of TWW-irrigated plots with fresh water (FW)-irrigated plots, together with the physiological status of the trees. Soil parameters included: continuous in-situ measurement of soil-water tension (SWT), soil oxygen, and soil redox potential, and periodic measurements of soil solution composition. Physiological parameters included: mineral composition of plant tissue from the leaves, trunk xylem and roots, root growth, yield, fruit setting, plant volume, and yield. TWW-irrigated plots were found to endure longer periods of low SWT indicating higher water content, accompanied by lower oxygen levels and more reduced conditions in comparison to FW-irrigated plots. The differences in these soil parameters between treatments were greater during the irrigation season than during the rainy period. The more reduced conditions in the TWW plots did not lead to significant differences in Fe or Mn concentrations in the soil solution or in plant leaves. TWW soil solution had significantly higher Na levels compared with FW. This did not affect the leaf Na content, but was expressed in substantially higher Na content in the root and trunk xylem, with up to seven times more trunk xylem Na in TWW-irrigated plants compared with FW-irrigated plants. Root growth was significantly hindered in TWW-irrigated plots compared with FW-irrigated plots. A negative correlation was found between root growth and the duration of hypoxic conditions, and similarly between root growth and the Na levels in the roots. TWW-irrigated plants had greater fruitlet numbers at the initial fruit-setting stage, but had a smaller number of fruit and a lower yield at harvest. The yield (kg/tree) negatively correlated with the duration of hypoxic conditions in the root zone but not with the Na levels in the roots or xylem. Our findings point towards a substantial role of oxygen deprivation as a major factor leading to the damage to TWW-irrigated orchards in clayey soils. Based on the assimilation of data, we suggest that a downward cascade is instigated in the TWW-irrigated orchards by increased input of Na into the soil, leading to degradation of soil hydraulic properties and reduced aeration. Impaired physiological functioning of the roots due to limited oxygen supply results in less roots growth, lower water uptake and impaired selectivity against Na uptake, thus imposing a negative feedback to increase soil water content, reduce aeration and root-zone oxygen availability for the roots, and further impair plant resistance to the high Na levels.

Primary Soil Formation And Dynamics Of The Evolutional Transformation Of Minerals Under Action Of Living Matter

We present the results of a comprehensive study of soil-forming processes under the influence of a long-term and end to end (7.5 years; twenty three vegetations) cultivating of the plants on initially lifeless mineral substrates (crushed granite, zeolite) under controlled conditions. The data were obtained under regulated conditions. It was shown that the higher plants (tomato, spring wheat) can actively participate in the pedogenesis process. We analyzed the evolutionary dynamics of the accumulation of organic matter and the dynamics of the biotic community. The result of the biogenic weathering minerals is decomposition of the rock, washing-out of the mineral elements, transformation of the minerals, formation of a secondary minerals and melkozem. We give consideration of the evolutionary dynamics of the chemical composition of plant tissues (roots, stems, leaves and reproductive organs). It was analyzed the percentage of the plant tissues the following chemical elements: P, S, Cl, Ca, Mg, Na, K, Fe, Si, Al, Mn, Zn. It was used the information approach for a quantitative analysis of the interrelation dynamics of changes in the chemical composition of the mineral substrates and chemical composition of plant tissues. The chemical composition of the mineral substrate evolutionary changes so that it is close to the information content of the plant root system. Studies processes of accumulation and transformation of the organic matter in the mineral substrate have shown that in a very short period of time under conditions of intense year-round cultivation of plants in the mineral substrates occur an intensive their enrichment by organic substance.

Nutrient deficiencies modify the ionomic composition of plant tissues: a focus on cross-talk between molybdenum and other nutrients in Brassica napus.

The composition of the ionome is closely linked to a plant's nutritional status. Under certain deficiencies, cross-talk induces unavoidable accumulation of some nutrients, which upsets the balance and modifies the ionomic composition of plant tissues. Rapeseed plants (Brassica napus L.) grown under controlled conditions were subject to individual nutrient deficiencies (N, K, P, Ca, S, Mg, Fe, Cu, Zn, Mn, Mo, or B) and analyzed by inductively high-resolution coupled plasma mass spectrometry to determine the impact of deprivation on the plant ionome. Eighteen situations of increased uptake under mineral nutrient deficiency were identified, some of which have already been described (K and Na, S and Mo, Fe, Zn and Cu). Additionally, as Mo uptake was strongly increased under S, Fe, Cu, Zn, Mn, or B deprivation, the mechanisms underlying the accumulation of Mo in these deficient plants were investigated. The results suggest that it could be the consequence of multiple metabolic disturbances, namely: (i) a direct disturbance of Mo metabolism leading to an up-regulation of Mo transporters such as MOT1, as found under Zn or Cu deficiency, which are nutrients required for synthesis of the Mo cofactor; and (ii) a disturbance of S metabolism leading to an up-regulation of root SO42- transporters, causing an indirect increase in the uptake of Mo in S, Fe, Mn, and B deficient plants.

Fertigation Strategies for Improving Water Use Efficiency and Limiting Nutrient Loss in Soilless Hippeastrum Production

Implementing nutrient management strategies in soilless culture, which improve water use efficiency (WUE) and limit the loss of eutrophying elements without affecting crop performance, is a priority for the floriculture industry. The aim of the current research was to assess the effect of two nutrient management strategies, based on electrical conductivity (EC) or nitrate-nitrogen (N-NO3−) concentration control on plant growth, ornamental quality, plant–water relations, mineral composition, and WUE of greenhouse Hippeastrum grown in semiclosed soilless system. The recirculating nutrient solution was discharged whenever a threshold EC value of 3.0 dS·m−1 was reached (EC-based strategy), or when N-NO3− concentration decreased below the limit of 1.0 mol·m−3 (nitrate-based strategy). There were no significant differences in terms of plant growth parameters, stomatal resistance, leaf water relations, and macronutrient composition in plant tissues between the two nutrient management strategies. In the EC- and the nitrate-based strategies, the recirculating nutrient solution was flushed 10 and 5 times, respectively. The water loss (WL) and the total water use (Wuse) in the EC-based strategy were significantly higher by 261.1% and 61.5%, respectively, compared with the N-NO3−-based strategy. In contrast with the EC-based strategy, the adoption of the N-NO3−-based strategy significantly minimized the nitrate, phosphate, and potassium emissions to the environment. The effective WUE of the system (WUES) recorded in the N-NO3−-based strategy was higher by 55.9% compared with the one recorded with the EC-based strategy.

Susceptibility Testing of <i>Mycobacterium frederiksbergense</i> Strains Isolated from Alfalfa Plants against Antibacterial Compounds

Mycobacteria constitute vast population of bacteria that are found in animals, plants and outer environments. Tuberculosis mycobacteria are a group that causes very dangerous diseases for human and animals. Nontuberculous mycobacteria are mainly environmental and are pathogenic in certain circumstances. There are reports of finding mycobacteria in plant tissues, which can be effective to survey in case of different infectious disease issues. In a previous study, we found mycobacteria strains in alfalfa vascular tissues and identified them to species level using 16S rRNA gene sequence analysis, causing some symptoms in plant tissues and aerial parts. As these rapidly growing mycobacteria (RGM) have the potential to cause opportunistic infections in human tissues, one of the most important issues for dealing with these agents is to find the best and most effective drug to treat them. Here, we conducted some assays to investigate the MIC of 7 antibiotics and two antibacterial agents against eight Mycobacterium frederiksbergense alfalfa isolated strains, in order to find the susceptible and resistant ones. We performed susceptibility testing based on broth microdilution method using Mueller hinton broth as the medium used. Results were different among the strains and different resistant and susceptible reactions were observed among different strains against each drug tested, but ethambutol resulted in similar high MIC for all of them. This variability could be attributed to many factors, such as plant tissue composition and developmental stage from which the strains have been isolated, existence and nature of drug targets and other factors such as test conditions and environmental causes. These results can bring us some insights into design and develop new drugs for treating these kinds of organisms, based on the variations in susceptibility reactions and the plant composition effect on them.

Dynamic carbon allocation into source and sink tissues determine within-plant differences in carbon isotope ratios.

Organs of C3 plants differ in their C isotopic signature (δ13C). In general, leaves are 13C-depleted relative to other organs. To investigate the development of spatial δ13C patterns, we induced different C allocation strategies by reducing light and nutrient availability for 12 months in the Mediterranean shrub Halimium halimifolium L. We measured morphological and physiological traits and the spatial δ13C variation among seven tissue classes during the experiment. A reduction of light (Low-L treatment) increased aboveground C allocation, plant height and specific leaf area. Reduced nutrient availability (Low-N treatment) enhanced C allocation into fine roots and reduced the spatial δ13C variation. In contrast, control and Low-L plants with high C allocation in new leaves showed a high δ13C variation within the plant (up to 2.5‰). The spatial δ13C variation was significantly correlated with the proportion of second-generation leaves from whole-plant biomass (R2=0.46). According to our results, isotope fractionation in dark respiration can influence the C isotope composition of plant tissues but cannot explain the entire spatial pattern seen. Our study indicates a foliar depletion in 13C during leaf development combined with export of relatively 13C-enriched C by mature source leaves as an important reason for the observed spatial δ13C pattern.

New HPLC Methods to Quantitate Terpenoid Aldehydes in Foliage of Cotton (Gossypium)

The cotton plant (Gossypium) produces protective terpenoid aldehydes in lysigenous pigment glands. These terpenoids include hemigossypolone, hemigossypolone-6-methyl ether, gossypol, gossypol-6-methyl ether, gossypol-6,6'- dimethyl ether, heliocides H1, H2, H3 and H4, and heliocides B1, B2, B3 and B4. Quantitation of these compounds is important to understand host-pest interactions. The column used in our previous HPLC/DAD method is no longer manufactured. Thus, three new methods were developed that use a Scientific Glass Engineering ProteCol-GP-C18 column maintained at 30 °C with gradients of acetonitrile:ethanol:isopropanol:N,N-dimethylformamide:methanol:ethyl acetate as the organic solvent and 0.1% H3PO4 as the aqueous solvent. Method one separates hemigossypolone, hemigossypolone-6- methyl ether, gossypol, gossypol-6-methyl ether, gossypol-6,6'-dimethyl ether and heliocides H1, H2, H3 and H4; method two separates these compounds as well as heliocides B1 and B4; method three allows resolution of heliocides B1, B2, B3 and B4 as well as the other terpenoids. The new methods provide superior separation of the methylated gossypol derivatives as well as the heliocides H1 to H4 and the heliocides B1, B2 and B3. The chromatogram is monitored at 272 nm, and spectra are stored over 240-600 nm. These methods allow cotton breeders to track the terpenoid aldehyde composition in plant tissues as they develop new cotton germplasm. The method has been used to establish for the first time the introgression from the wild cotton G. sturtianum into commercial Upland cotton G. hirsutum. Keywords: Cotton terpenoid aldehydes, Gossypium sturtianum, gossypol, gossypol-6-6′-dimethyl ether, hemigossypolone, heliocides, HPLC analysis.

The structure and chemical composition of plant tissues revealed by high resolution attenuated total internal reflectance imaging.

The structure and chemical composition of plant tissues revealed by high resolution attenuated total internal reflectance imaging.

Edaphic factors and plant–insect interactions: direct and indirect effects of serpentine soil on florivores and pollinators

Edaphic factors can lead to differences in plant morphology and tissue chemistry. However, whether these differences result in altered plant-insect interactions for soil-generalist plants is less understood. We present evidence that soil chemistry can alter plant-insect interactions both directly, through chemical composition of plant tissue, and indirectly, through plant morphology, for serpentine-tolerant Mimulus guttatus (Phrymaceae). First, we scored floral display (corolla width, number of open flowers per inflorescence, and inflorescence height), flower chemistry, pollinator visitation and florivory of M. guttatus growing on natural serpentine and non-serpentine soil over 2 years. Second, we conducted a common garden reciprocal soil transplant experiment to isolate the effect of serpentine soil on floral display traits and flower chemistry. And last, we observed arrays of field-collected inflorescences and potted plants to determine the effect of soil environment in the field on pollinator visitation and florivore damage, respectively. For both natural and experimental plants, serpentine soil caused reductions in floral display and directly altered flower tissue chemistry. Plants in natural serpentine populations received fewer pollinator visits and less damage by florivores relative to non-serpentine plants. In experimental arrays, soil environment did not influence pollinator visitation (though larger flowers were visited more frequently), but did alter florivore damage, with serpentine-grown plants receiving less damage. Our results demonstrate that the soil environment can directly and indirectly affect plant-mutualist and plant-antagonist interactions of serpentine-tolerant plants by altering flower chemistry and floral display.

Highway contributions to reactive nitrogen deposition: tracing the fate of vehicular NOx using stable isotopes and plant biomonitors

While epidemiologists have long acknowledged that automobile emissions create corridors of increased NOx concentrations near highways, the influence of these emissions on dry nitrogen (N) deposition and effects on surrounding ecosystems are not well-characterized. This study used stable isotopes in plant tissue and dry N deposition to examine the extent of N deposition from automobile emissions along a roadside transect spanning 400 m perpendicular to a moderately trafficked highway (33,000 vehicles per day). Passive samplers were deployed monthly for four months at six stations to collect dry deposition of nitric acid (HNO3) and nitrogen dioxide (NO2), analyzed for concentration and natural abundance isotopic composition (δ15N). Agrostis perennans (bentgrass) and Panicum virgatum (switchgrass) were deployed as biomonitors to examine relative sources of N to plant tissue. Both NO2 flux and δ15N–NO2 values were significantly higher close to the road indicating a high proportion of automobile-sourced N is deposited near-road. Further, this near-road deposition occurred primarily as NO2 prior to oxidation to HNO3, as HNO3 fluxes were an order of magnitude lower than NO2 fluxes and were highest midway through the transect. Plant tissue δ15N values were higher near the road, signifying the influence of automobile emissions on plant tissue composition. Importantly, N flux near the road was four times higher than background N flux measured at the nearest regional dry deposition monitoring locations. We extrapolated these results to demonstrate that the observed spatial patterns of concentrated N deposition impact our understanding of regional N deposition to watersheds when applied to a metropolitan area.

No cumulative effect of 10 years of elevated [CO2] on perennial plant biomass components in the Mojave Desert

Elevated atmospheric CO2 concentrations ([CO2 ]) generally increase primary production of terrestrial ecosystems. Production responses to elevated [CO2 ] may be particularly large in deserts, but information on their long-term response is unknown. We evaluated the cumulative effects of elevated [CO2 ] on primary production at the Nevada Desert FACE (free-air carbon dioxide enrichment) Facility. Aboveground and belowground perennial plant biomass was harvested in an intact Mojave Desert ecosystem at the end of a 10-year elevated [CO2 ] experiment. We measured community standing biomass, biomass allocation, canopy cover, leaf area index (LAI), carbon and nitrogen content, and isotopic composition of plant tissues for five to eight dominant species. We provide the first long-term results of elevated [CO2 ] on biomass components of a desert ecosystem and offer information on understudied Mojave Desert species. In contrast to initial expectations, 10 years of elevated [CO2 ] had no significant effect on standing biomass, biomass allocation, canopy cover, and C : N ratios of above- and belowground components. However, elevated [CO2 ] increased short-term responses, including leaf water-use efficiency (WUE) as measured by carbon isotope discrimination and increased plot-level LAI. Standing biomass, biomass allocation, canopy cover, and C : N ratios of above- and belowground pools significantly differed among dominant species, but responses to elevated [CO2 ] did not vary among species, photosynthetic pathway (C3 vs. C4 ), or growth form (drought-deciduous shrub vs. evergreen shrub vs. grass). Thus, even though previous and current results occasionally show increased leaf-level photosynthetic rates, WUE, LAI, and plant growth under elevated [CO2 ] during the 10-year experiment, most responses were in wet years and did not lead to sustained increases in community biomass. We presume that the lack of sustained biomass responses to elevated [CO2 ] is explained by inter-annual differences in water availability. Therefore, the high frequency of low precipitation years may constrain cumulative biomass responses to elevated [CO2 ] in desert environments.