Main Pigment Research Articles

A preliminary study of Liu Kang\u2019s palette and the discovery and interpretation of hidden paint layers

This paper presents an overview of the results from the ongoing study on the materials and painting technique of the pioneering Singapore artist—Liu Kang. The paintings Zuo La Lu and Nude, which represent two of Liu Kang’s early and distinct artistic phases—Paris and Shanghai—were investigated for the first time using a combination of non- and micro-invasive techniques. The aim of this study was to identify the main pigments used by the artist and to add to the existing research on the artist’s painting methods. The results show that the majority of pigments used in both paintings are similar and include Prussian blue, ultramarine, viridian, strontium yellow, chrome yellow, cadmium yellow, iron oxides, lead, zinc and barium whites, bone black and organic red. Particularly interesting is the predominance of lead white in Zuo La Lu and zinc white in Nude. A comparison of the ground layers also indicates the presence of a lead white admixture in Zuo La Lu while its absence in Nude may point to a characteristic difference between two artistic phases, possibly determined by the availability of materials. The imaging methods revealed hidden compositions: the view of a canal house behind Zuo La Lu, and a mystery outdoor view behind Nude. Although these investigative methods permitted some visualisation of the discarded compositions, it remains difficult to determine their details.

Functional diversification of two bilin reductases for light perception and harvesting in unique cyanobacterium Acaryochlorismarina MBIC 11017.

Bilin pigments play important roles for both light perception and harvesting in cyanobacteria by binding to cyanobacteriochromes (CBCRs) and phycobilisomes (PBS), respectively. Among various cyanobacteria, Acaryochlorismarina MBIC 11017 (A.marina 11017) exceptionally uses chlorophyll d as the main photosynthetic pigment absorbing longer wavelength light than the canonical pigment, chlorophyll a, indicating existence of a system to sense longer wavelength light than others. On the other hand, A.marina 11017 has the PBS apparatus to harvest short-wavelength orange light, similar to most cyanobacteria. Thus, A.marina 11017 might sense longer wavelength light and harvest shorter wavelength light by using bilin pigments. Phycocyanobilin (PCB) is the main bilin pigment of both systems. Phycocyanobilin:ferredoxin oxidoreductase (PcyA) catalyzes PCB synthesis from biliverdin via the intermediate 181 ,182 -dihydrobiliverdin (181 ,182 -DHBV), resulting in the stepwise shortening of the absorbing wavelengths. In this study, we found that A.marina 11017 exceptionally encodes two PcyA homologs, AmPcyAc and AmPcyAp. AmPcyAc is encoded on the main chromosome with most photoreceptor genes, whereas AmPcyAp is encoded on a plasmid with PBS-related genes. High accumulation of 181 ,182 -DHBV for extended periods was observed during the reaction catalyzed by AmPcyAc, whereas 181 ,182 -DHBV was transiently accumulated for a short period during the reaction catalyzed by AmPcyAp. CBCRs could sense longer wavelength far-red light through 181 ,182 -DHBV incorporation, whereas PBS could only harvest orange light through PCB incorporation, suggesting functional diversification of PcyA as AmPcyAc and AmPcyAp to provide 181 ,182 -DHBV and PCB to the light perception and harvesting systems, respectively.

Deep chemometrics for nondestructive photosynthetic pigments prediction using leaf reflectance spectra

The need for the rapid assessment of the photosynthetic pigment contents in plants has encouraged the development of studies to produce nondestructive quantification methods. This need is driven by the fact that data on the photosynthetic pigment contents can provide a variety of important information that is related to plant conditions. Using deep chemometrics, we developed a novel one-dimensional convolutional neural network (CNN) model to predict the photosynthetic pigment contents in a nondestructive and real-time manner. Intact leaf reflectance spectra from spectroscopic measurements were used as the inputs. The prediction was simultaneously carried out for three main photosynthetic pigments, i.e., chlorophyll, carotenoid and anthocyanin. The experimental results show that the prediction accuracy is very satisfying, with a mean absolute error (MAE) = 0.0122 ± 0.0004 for training and 0.0321 ± 0.0022 for validation (data range of 0–1).

Structural Characteristics and Hypolipidemic Activity of Theabrownins from Dark Tea Fermented by Single Species Eurotium cristatum PW-1

Recently, studies on theabrownins (TBs), the main bioactive polymeric pigments found in dark tea, have received increasing attention for its health effects. Thus far, information on their structural characteristics is unclear. In the present study, theabrownins were isolated from single species Eurotium cristatum PW-1-fermented loose tea and their structural and hypolipidemic characteristics were studied for the first time. The theabrownins were fractionated by their molecular weights and were then analyzed. Ultraviolet–visible spectrophotometry (UV-Vis) and Flourier transformation infrared spectroscopy (FT-IR) showed that they were polymerized phenolic substances containing abundant hydroxy and carboxyl groups. All theabrownin samples exhibited hypolipidemic activity in high-fat zebrafish; among which TBs-10-30k sample, decreased lipid level in high-fat zebrafish to 51.57% at 1000 μg/mL, was most effective. It was found that TBs-10-30k was a type of amorphous and thermostable polymer with slice shape and smooth surface under scanning electron microscope (SEM). Atomic force microscope (AFM) analysis showed that it had island-like structure because of aggregation of theabrownin molecules. Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) analysis further showed that the main pyrolytic products of TBs-10-30k were hexadecanoic acid (33.72%), phenol (14.90%), and eicosane (12.95%), indicating TBs-10-30k was mainly composed of phenols, lipids, saccharides, and proteins. These results not only facilitate subsequent identification of theabrownins, but also provide insights into the applications of theabrownins in functional foods.

Seasonal Changes in the Concentration of Photosynthetic Pigments Palmaria palmata (Linnaeus) F. Weber & D. Mohr

The article presented the overview of the main seasonal dynamics of photosynthetic pigments (chlorophyll a, carotenoids and phycobiliproteins) as well as their ratios for the mass species of the Murmansk coast of the Barents Sea red algae Palmaria palmata. The concentration of pigments depends on the level of illumination and temperature which is statistically confirmed. The results of the research showed that the chlorophyll content of Palmaria palmata is characterized by a significant decrease in summer and an increase in winter which is in contrast to the change in the level of illumination. It was proved that in winter with a decrease in light, the efficiency of photosynthesis is provided by the accumulation of pigments including phycobilins. It is suggested that the relationship of reproduction, namely the release of tetraspores with the reduction of phycobiliproteins, since the presented process requires significant energy costs. It is shown that the concentration of phycobilins decreases with increasing light intensity. Prolonged presence of algae under high light intensities reduces the amount of photosynthetic pigments. The results of the research showed that the number of pigments decreases with low temperatures and vice versa their number increases with increasing temperature. A significant negative correlation between the water temperature and the main pigments of the photosynthetic apparatus – chlorophyll a and carotenoids was revealed. The concentration of carotenoids and phycobilins depends on the function they perform: in summer - photoprotectors, in winter-additional light collectors. Palmaria has a maximum content during the polar night. Significant changes in the ratios of Car/Chl a, PhE/ Chl a, PhE / PhE depending on environmental factors are shown.

Density functional theory studies on the excited-state properties of Bilirubin molecule

Bilirubin is the main pigment in human bile, which is closely related to human health. Bilirubin combining with fluorescent protein represents a new type of fluorescent chromophore and has important applications in the field of biological imaging and biosensor. Due to the lack of efficient and accurate electronic structure methods, the electronic structure and excited-state properties of bilirubin molecule are not characterized quantitatively and accurately. Firstly, the vertical absorption energy, oscillator strength and vertical emission energy of the lowest singlet excited state of bilirubin molecule are calculated by combining the implicit solvent model and the linear response time-dependent density functional theory (TDDFT) method. Compared to the experimental data and high-level RI-ADC(2) calculation, the prediction performance of a series of density functional methods is systematically investigated. The results show that the optimally-tuned range separated density functional method has the best overall performance and the minimum absolute and relative errors. This is obviously due to the fact that the suitable proportion of exact exchange included in density functionals can produce neither delocalized nor localized electronic structures. Based on the produced wavefunction by the optimally-tuned method, the excited-state characteristics of the S<sub>1</sub> state of bilirubin molecule indicate a hybrid local and charge transfer excitation, based on the quantitative characterization using hole-electron analysis and interfragment charge transfer method. This work can provide a theoretical basis for the study of excited-state dynamics and spectral properties of bilirubin molecules and the optimally tuned range-separated DFT method also provide a reliable and efficient theoretical tool to study the excited-state properties of other biomolecular systems in the future.

Flesh Color Diversity of Sweet Potato: An Overview of the Composition, Functions, Biosynthesis, and Gene Regulation of the Major Pigments

Sweet potato is a multifunctional root crop and a source of food with many essential nutrients and bioactive compounds. Variations in the flesh color of the diverse sweet potato varieties are attributed to the different phytochemicals and natural pigments they produce. Among them, carotenoids and anthocyanins are the main pigments known for their antioxidant properties which provide a host of health benefits, hence, regarded as a major component of the human diet. In this review, we provide an overview of the major pigments in sweet potato with much emphasis on their biosynthesis, functions, and regulatory control. Moreover, current findings on the molecular mechanisms underlying the biosynthesis and accumulation of carotenoids and anthocyanins in sweet potato are discussed. Insights into the composition, biosynthesis, and regulatory control of these major pigments will further advance the biofortification of sweet potato and provide a reference for breeding carotenoid- and anthocyanin-rich varieties.

Comparative Transcriptomics Provides Insight into Floral Color Polymorphism in a Pleione limprichtii Orchid Population.

Floral color polymorphism can provide great insight into species evolution from a genetic and ecological standpoint. Color variations between species are often mediated by pollinators and are fixed characteristics, indicating their relevance to adaptive evolution, especially between plants within a single population or between similar species. The orchid genus Pleione has a wide variety of flower colors, from violet, rose-purple, pink, to white, but their color formation and its evolutionary mechanism are unclear. Here, we selected the P. limprichtii population in Huanglong, Sichuan Province, China, which displayed three color variations: Rose-purple, pink, and white, providing ideal material for exploring color variations with regard to species evolution. We investigated the distribution pattern of the different color morphs. The ratio of rose-purple:pink:white-flowered individuals was close to 6:3:1. We inferred that the distribution pattern may serve as a reproductive strategy to maintain the population size. Metabolome analysis was used to reveal that cyanindin derivatives and delphidin are the main color pigments involved. RNA sequencing was used to characterize anthocyanin biosynthetic pathway-related genes and reveal different color formation pathways and transcription factors in order to identify differentially-expressed genes and explore their relationship with color formation. In addition, qRT-PCR was used to validate the expression patterns of some of the genes. The results show that PlFLS serves as a crucial gene that contributes to white color formation and that PlANS and PlUFGT are related to the accumulation of anthocyanin which is responsible for color intensity, especially in pigmented flowers. Phylogenetic and co-expression analyses also identified a R2R3-MYB gene PlMYB10, which is predicted to combine with PlbHLH20 or PlbHLH26 along with PlWD40-1 to form an MBW protein complex (MYB, bHLH, and WDR) that regulates PlFLS expression and may serve as a repressor of anthocyanin accumulation-controlled color variations. Our results not only explain the molecular mechanism of color variation in P. limprichtii, but also contribute to the exploration of a flower color evolutionary model in Pleione, as well as other flowering plants.

Light Emission in Betalains: From Fluorescent Flowers to Biotechnological Applications.

The discovery of visible fluorescence in the plant pigments betalains revealed the existence of fluorescent patterns in flowers of plants of the order Caryophyllales, where betalains substitute anthocyanins. The serendipitous initial discovery led to a systemized characterization of the role of different substructures on the photophysical phenomenon. Strong fluorescence is general to all members of the family of betaxanthins linked to the structural property that the betalamic acid moiety is connected to an amine group. This property has led to bioinspired tailor-made probes and to the development of novel biotechnological applications in screening techniques or microscopy labeling. Here, we comprehensively review the photophysics, photochemistry, and photobiology of betalain fluorescence and describe all current applications.

A Comparative Assessment of Pigment Extraction from Avian Eggshells Using Two Analytical Protocols

There are two main methods to extract pigments from avian eggshells. There are those using strong acids (e.g. sulphuric, hydrochloric or formic), that allow for a quantification of pigment concentrations but with which samples are destroyed. Alternatively, there are methods employing weaker acids (e.g. acetic), with which samples are not destroyed, although pigment concentrations may not be quantified and only their presence is detected. In some cases, there may be a need to quantify pigments in samples in which the pigments have already been detected. Here, we assess whether the quantity of pigments extracted from eggshells using a strong acid is affected by previous treatment of eggshells with a weak acid. For this, we used eggshells of Kentish Plovers Charadrius alexandrinus and domestic Japanese Quails Coturnix japonica, and aliquots of individual eggshells treated either with both acids (first applying a weak acid and then a strong acid) or only with the strong acid. Quantities of extracted protoporphyrin and biliverdin (the main eggshell pigments) were lower when using a strong acid after application of a weak acid. However, there were significant positive correlations between the quantities of pigments extracted using the two methods, suggesting that eggshell samples used to determine pigment presence may still be usable to quantify pigment concentrations using a strong acid.—Gomez, J., Ramo, C., Canales, J.A., Garcia, I.M., Castro, M., Perez-Hurtado, A. & Amat, J.A. (2020). A comparative assessment of pigment extraction from avian eggshells using two analytical protocols.

Phytoplankton community structure during monsoon transition period in the Lembeh strait of north Sulawesi, Indonesia

Phytoplankton community structure based on photosynthetic pigments in the Lembeh strait was studied in April 2017, during the period of monsoon transition. With data of the spatial distribution of phytoplankton community structures and environmental factors, the main factors leading to the changes in phytoplankton community structure and distribution of phytoplankton abundance were discussed. Our results show that the phosphate concentration in the north of the strait was higher than that in the south, while the distribution of nitrogen concentration was just the opposite. The silicate concentration had a significance high concentration in the bottom water of the northern strait, indicating that there was a sinking ocean current from the north. Different from previous surveys, the N/P ratio of water ranges from 2.6 to 4.56, proving that nitrogen is the nutrient limiting factor in this survey, which was due to increased phosphorus concentrations due to continuous heavy rains. The main pigments were Chl b, 19-hex-fucoxanthin and fucoxanthin during the period of monsoon transition. Chl a concentration was significantly higher in the north of the strait than in the south, and Chl a concentration at surface was higher than that at bottom. This is because the thrive of cyanobacteria in the northern strait, which were the main group in the Lembeh strait during monsoon transition. They can grow and reproduce in the nutrient-poor sea water, since they can use phosphonates as a source of phosphorus during metabolic processes. Compared with surveys conducted during SE monsoonal period, the abundance of phytoplankton in monsoon transition period was significantly lower. Because the upwelling brought sufficient nutrients to the water, which meet the require of phytoplankton growth, allowing phytoplankton to grow well in SE monsoon. On the whole, the results show that the changes in phytoplankton community structure and distribution of phytoplankton abundance during the monsoon transition period in the Lembeh strait is mainly affected by nutrients.

Ontogenetic Changes of the Pigment Composition of Leaves in Cyan Oil Flax Variety in the Steppe Zone Of Ukraine

In recent years, oil flax has been very popular in Ukraine. Different spheres of the use of culture indicate good adaptive opportunities for growing oil flax in different regions of Ukraine. The aim of this work is to study the content and ratio of the main photosynthetic pigments of the flax variety of oilseed Cyan grown in ontogenesis. Plants were grown in natural open ground. The number of pigments was determined by spectrophotometric method. This is research data on the content of the main photosynthetic pigments in flax of Tsian. The content of chlorophyll a, b and carotenoids was studied at three stages of development: at the stage of 8-10 leaves, budding, flowering. It was established that the amount of chlorophyll a exceeds the content of chlorophyll b at all stages of development. An increase in the pigment content during ontogenesis to the flowering stage was revealed, with the exception of chlorophyll b. At the stage of the at the stage of 8-10 leaves in the Tsian variety, the amount of chlorophyll a ranged from min 754.74 ± 63.768 μg/g, max 1582.82 ± 126.973 μg/g wet weight, the amount of chlorophyll b ranging from min 203.23 ± 17.549 to max 602.24 ± 46.577 μg g wet weight, and carotenoids from min 220.99 ± 18.388 to max 409.94 ± 37.572 μg/g fresh weight, depending on the year of study. In the budding phase, the minimum content of chlorophyll a was min 1444.87 ± 105.771, and the maximum max 2027.34 ± 174.258 μg/g wet weight, chlorophyll b: from min 553.23 ± 48.345 to max 1733.69 ± 109.675 μg/g raw weight, and carotenoids: from min 354.81 ± 26.759 to max 402.63 ± 26.765 μg/g wet weight, depending on the year of study. In the flowering phase, the following indicators were observed: chlorophyll a content from min 1804.43 ± 164.425 to max 2370.56 ± 207.589 μg/g wet weight, chlorophyll b from min 1055.24 ± 89.562 μg/g wet weight to max 1649.21 ± 107.258 μg/g, and carotenoids from min 472.19 ± 36.141 μg/g to max 519.3322 ± 39.911 μg/g, depending on the year of study. The ratio of the number of chlorophylls and the sum of chlorophylls to carotenoids varies depending on the stage of development of the variety and growing conditions.

Jasmonic acid enhances the resistance of potato plants in vitro to salt stress

The protective effect of jasmonic acid (JA) was evaluated under stress (100 mM NaCl) condition. The investigations were carried on potato plants (Solanum tuberosum L.) of the mid-season variety Lugovskoy. Plant-regenerants were grafted and cultured in test tubes on modified Murashige-Skoog agar medium in the absence (control) or in the presence of JA at concentrations of 0.001; 0.1 and 10 M under optimal growing conditions or with the addition of NaCl. After 28 days of cultivation, growth (length of stem and root, number of tiers and leaves, plant mass) and physiological (proline content and photosynthetic pigments, determination of the osmotic potential of cell exudate) of the plants were assessed. For the first time it has been shown that jasmonic acid (0.1 and 10 M) manifests a pronounced protective effect on potato plants under salt stress condition. The protective effect based on the partial removal of the salt negative effect on the main photosynthetic pigments and the maintenance of the osmotic status of cell contents during salinization.

Characterization and identification of lacquer films from the Qin and Han dynasties

A comprehensive investigation was undertaken of red–black lacquer films excavated from a tomb in the Qin and Han Dynasty period (221 BC to AD 8). Cross-sectional observation was conducted via metallomicroscopy and field-emission scanning electron microscopy (FE-SEM). Morphological characteristics were investigated via FE-SEM with energy dispersive X-ray spectrometry (EDX). X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were also conducted. The results of the cross-sectional analysis showed that the finished lacquer films on the wood body included a ground layer with coarse materials and a lacquer layer with delicate materials. Both SEM and EDX indicated that carbon black was used as the main black pigment, and cinnabar was used as the main red pigment. Compared with the standard card test, the XRD patterns of the Chinese lacquer were similar to that of quartz (SiO2), indicating that SiO2 was used as a putty powder during lacquer finishing. Compared with the FTIR spectrum of the fresh lacquer film, only a small amount of free carbonyl was found in the degraded lacquer, and some organosilicates were likely generated during degradation spanning thousands of years.

Study on cyanidin metabolism in petals of pink-flowered strawberry based on transcriptome sequencing and metabolite analysis

BackgroundPink-flowered strawberry is a promising new ornamental flower derived from intergeneric hybridization (Fragaria × Potentilla) with bright color, a prolonged flowering period and edible fruits. Its flower color ranges from light pink to red. Pigment compounds accumulated in its fruits were the same as in cultivated strawberry fruits, but different from that in its flowers. However, the transcriptional events underlying the anthocyanin biosynthetic pathway have not been fully characterized in petal coloration. To gain insights into the regulatory networks related to anthocyanin biosynthesis and identify the key genes, we performed an integrated analysis of the transcriptome and metabolome in petals of pink-flowered strawberry.ResultsThe main pigments of red and dark pink petals were anthocyanins, among which cyanidins were the main compound. There were no anthocyanins detected in the white-flowered hybrids. A total of 50,285 non-redundant unigenes were obtained from the transcriptome databases involved in red petals of pink-flowered strawberry cultivar Sijihong at three development stages. Amongst the unigenes found to show significant differential expression, 57 were associated with anthocyanin or other flavonoid biosynthesis, in which they were regulated by 241 differentially expressed members of transcription factor families, such as 40 MYBs, 47 bHLHs, and 41 NACs. Based on a comprehensive analysis relating pigment compounds to gene expression profiles, the mechanism of flower coloration was examined in pink-flowered strawberry. A new hypothesis was proposed to explain the lack of color phenotype of the white-flowered strawberry hybrids based on the transcriptome analysis. The expression patterns of FpDFR and FpANS genes corresponded to the accumulation patterns of cyanidin contents in pink-flowered strawberry hybrids with different shades of pink. Moreover, FpANS, FpBZ1 and FpUGT75C1 genes were the major factors that led to the absence of anthocyanins in the white petals of pink-flowered strawberry hybrids. Meanwhile, the competitive effect of FpFLS and FpDFR genes might further inhibit anthocyanin synthesis.ConclusionsThe data presented herein are important for understanding the molecular mechanisms underlying the petal pigmentation and will be powerful for integrating novel potential target genes to breed valuable pink-flowered strawberry cultivars.

Carotenoids of Capsicum Fruits: Pigment Profile and Health-Promoting Functional Attributes.

Pepper of the Capsicum species is a common ingredient in various food preparations by different cultures worldwide. The Capsicum is recognised by its five main domesticated species, namely Capsicum annuum, C. baccatum, C. chinense, C. frutescens and C. pubescens. The genetic diversity in Capsicum offers fruits in wide ranges of morphology and carotenoid profile. Carotenoids enhance the value of pepper from a nutritional standpoint, despite being commonly prized for the pharmacologically active pungent capsaicinoids. Carotenoids of pepper comprise mainly of the unique, powerful and highly stable capsanthin and capsoroubin, together with β-carotene, β-cryptoxanthin, lutein, zeaxanthin, antheraxanthin and violaxanthin. These carotenoids are present at diverse profile and varying levels, biosynthetically connected to the fruit maturity stages. This review describes the health-promoting functional attributes of the carotenoids that are mainly associated with their excellent role as lipophilic antioxidants. Capsicum as a great source of carotenoids is discussed in the aspects of main domesticated species, biosynthesis, pigment profile, antioxidant activity and safety. Findings from a number of in vitro, in vivo and clinical studies provided appreciable evidence on the protective effects of pepper’s carotenoids against degenerative diseases. Hence, pepper with its functional carotenoids might be recommended in health-promoting and disease preventing strategies.

A Molecular Biology Tool Kit for the Phototrophic Firmicute Heliobacterium modesticaldum.

The heliobacteria are members of the bacterial order Clostridiales and form the only group of phototrophs in the phylum Firmicutes Several physiological and metabolic characteristics make them an interesting subject of investigation, including their minimalist photosynthetic system, nitrogen fixation abilities, and ability to reduce toxic metals. While the species Heliobacterium modesticaldum is an excellent candidate as a model system for the family Heliobacteriaceae, since an annotated genome and transcriptomes are available, studies in this organism have been hampered by the lack of genetic tools. We adapted techniques for genetic manipulation of related clostridial species for use with H. modesticaldum Five heliobacterial DNA methyltransferase genes were expressed in an Escherichia coli strain engineered as a conjugative plasmid donor for broad-host-range plasmids. Premethylation of the shuttle vectors before conjugation into H. modesticaldum is absolutely required for production of transconjugant colonies. The introduced shuttle vectors are maintained stably and can be recovered using a modified minipreparation procedure developed to inhibit endogenous DNase activity. Furthermore, we describe the formulation of various growth media, including a defined medium for metabolic studies and isolation of auxotrophic mutants.IMPORTANCE Heliobacteria are anoxygenic phototrophic bacteria with the simplest known photosynthetic apparatus. They are unique in using bacteriochlorophyll g as their main pigment and lacking a peripheral antenna system. Until now, research on this organism has been hampered by the lack of a genetic transformation system. Without such a system, gene knockouts, site-directed mutations, and gene expression studies cannot be performed to help us further understand or manipulate the organism. Here we report the genetic transformation of a heliobacterium, which should enable future genetic studies in this unique phototrophic organism.

Genetic Characteristic and RNA-Seq Analysis in Transparent Mutant of Carp-Goldfish Nucleocytoplasmic Hybrid.

In teleost, pigment in the skin and scales played important roles in various biological processes. Iridophores, one of the main pigment cells in teleost, could produce silver pigments to reflect light. However, the specific mechanism of the formation of silver pigments is still unclear. In our previous study, some transparent mutant individuals were found in the carp–goldfish nucleocytoplasmic hybrid (CyCa hybrid) population. In the present study, using transparent mutants (TM) and wild type (WT) of the CyCa hybrid as a model, firstly, microscopic observations showed that the silver pigments and melanin were both lost in the scales of transparent mutants compared to that in wild types. Secondly, genetic study demonstrated that the transparent trait in the CyCa hybrid was recessively inherent, and controlled by an allele in line with Mendelism. Thirdly, RNA-Seq analysis showed that differential expression genes (DEGs) between wild type and transparent mutants were mainly enriched in the metabolism of guanine, such as hydrolase, guanyl nucleotide binding, guanyl ribonucleotide binding, and GTPase activity. Among the DEGs, purine nucleoside phosphorylase 4a (pnp4a) and endothelin receptor B (ednrb) were more highly expressed in the wild type compared to the transparent mutant (p < 0.05). Finally, miRNA-Seq analysis showed that miRNA-146a and miR-153b were both more highly expressed in the transparent mutant compared to that in wild type (p < 0.05). Interaction analysis between miRNAs and mRNAs indicated that miRNA-146a was associated with six DEGs (MGAT5B, MFAP4, GP2, htt, Sema6b, Obscn) that might be involved in silver pigmentation.

Estimating persistent oil contamination in tropical region using vegetation indices and random forest regression

The persistence of soil contamination after cessation of oil activities remains a major environmental issue in tropical regions. The assessment of the contamination is particularly difficult on vegetated sites, but promising advances in reflectance spectroscopy have recently emerged for this purpose. This study aimed to exploit vegetation reflectance for estimating low concentrations of Total Petroleum Hydrocarbons (TPH) in soils. A greenhouse experiment was carried out for 42 days on Cenchrus alopecuroides (L.) under realistic tropical conditions. The species was grown on oil-contaminated mud pit soils from industrial sites, with various concentrations of TPH. After 42 days, a significant decrease in plant growth and leaf chlorophyll and carotenoid contents was observed for plants exposed to 5–19 g kg−1 TPH in comparison to the controls (p < 0.05). Conversely, pigment contents were higher for plants exposed to 1 g kg−1 TPH (hormesis phenomenon). These modifications proportionally affected the reflectance of C. alopecuroides at leaf and plant scales, especially in the visible region around 550 and 700 nm. 33 vegetation indices were used for linking the biochemical and spectral responses of the species to oil using elastic net regressions. The established models indicated that chlorophylls a and b and β-carotene were the main pigments involved in the modifications of reflectance (R2 > 0.7). The same indices also succeeded in estimating the concentrations of TPH using random forest regression, at leaf and plant scales (RMSE = 1.46 and 1.63 g kg−1 and RPD = 5.09 and 4.44, respectively). Four out of the 33 indices contributed the most to the models (>75%). This study opens up encouraging perspectives for monitoring the cessation of oil activities in tropical regions. Further researches will focus on the application of our approach at larger scale, on airborne and satellite imagery.

Jasmonic Acid Enhances the Potato Plant Resistance to the Salt Stress in Vitro

The protective effect of jasmonic acid (JA) was evaluated under the stress conditions (100 mM NaCl). The potato plants Solanum tuberosum L, mid-season variety Lugovskoy, were used in the experiments. The plant-regenerants were grafted and grown in test tubes on the modified Murashige and Skoog agar medium in the absence (control) or presence of JA at concentrations of 0.001, 0.1, and 10 μM under the optimal conditions or with addition of NaCl. After 28 days of cultivation, the growth (stem and root lengths, tier and leaf numbers, and plant mass) and physiological (proline and photosynthetic pigment contents and teh osmotic potential of cell exudate) characteristics of the plants were assessed. Jasmonic acid (0.1 and 10 μM) has been demonstrated to display a pronounced protective effect on potato plants under the salt stress condition. JA abolished partially the negative salt effect on the main photosynthetic pigments and maintained the cell osmotic status during salinization.