Evolution and Dynamic Transcriptome of Key Genes of Photoperiodic Flowering Pathway in Water Spinach (Ipomoea aquatica).

The photoperiod is a major environmental factor in flowering control. Water spinach flowering under the inductive short-day condition decreases the yield of vegetative tissues and the eating quality. To obtain an insight into the molecular mechanism of the photoperiod-dependent regulation of the flowering time in water spinach, we performed transcriptome sequencing on water spinach under long- and short-day conditions with eight time points. Our results indicated that there were 6615 circadian-rhythm-related genes under the long-day condition and 8691 under the short-day condition. The three key circadian-rhythm genes, IaCCA1, IaLHY, and IaTOC1, still maintained single copies and similar IaCCA1, IaLHY, and IaTOC1 feedback expression patterns, indicating the conservation of reverse feedback. In the photoperiod pathway, highly conserved GI genes were amplified into two copies (IaGI1 and IaGI2) in water spinach. The significant difference in the expression of the two genes indicates functional diversity. Although the photoperiod core gene FT was duplicated to three copies in water spinach, only IaFT1 was highly expressed and strongly responsive to the photoperiod and circadian rhythms, and the almost complete inhibition of IaFT1 in water spinach may be the reason why water spinach does not bloom, no matter how long it lasts under the long-day condition. Differing from other species (I. nil, I. triloba, I. trifida) of the Ipomoea genus that have three CO members, water spinach lacks one of them, and the other two CO genes (IaCO1 and IaCO2) encode only one CCT domain. In addition, through weighted correlation network analysis (WGCNA), some transcription factors closely related to the photoperiod pathway were obtained. This work provides valuable data for further in-depth analyses of the molecular regulation of the flowering time in water spinach and the Ipomoea genus.

Application of microbial agents in organic solid waste composting: a review.

The rapid growth of organic solid waste has recently exacerbated environmental pollution problems, and its improper treatment has led to the loss of a large number of biomass resources. Here, we expound the advantages of microbial agents composting compared with conventional organic solid waste treatment technology, and review the important role of microbial agents composting in organic solid waste composting from the aspects of screening and identification, optimization of conditions, mechanism of action, combination with other technologies and ultra-high-temperature and ultra-low-temperature microbial composting. We discuss the value of microorganisms with different growth conditions in organic solid waste composting, and put forward a seasonal multi-temperature composite microbial composting technology. Provide new ideas for the all-round treatment of microbial agents in organic solid waste in the future. © 2024 Society of Chemical Industry.

Influence of polyvinyl chloride microplastic on chromium uptake and toxicity in sweet potato.

The extensive use of plastic products and rapid industrialization have created a universal concern about microplastics (MPs). MPs can pose serious environmental risks when combined with heavy metals. However, current research on the combined effects of MPs and hexavalent chromium [Cr(VI)] on plants is insufficient. Herein, a 14-day hydroponic experiment was conducted to investigate the impact of PVC MPs (100 and 200 mg/L) and Cr(VI) (5, 10, and 20 µM) alone and in combination on sweet potato. Results showed that combined Cr(VI) and PVC MPs affected plant growth parameters significantly, but PVC MPs alone did not. The combined application of PVC MPs and Cr(VI) resulted in a decrease in plant height (24-65%), fresh biomass per plant (36-71%), and chlorophyll content (16-34%). Cr(VI) bioaccumulation increased with the increase in its doses, with the highest concentration of Cr(VI) in the leaves (16.45 mg/kg), stems (13.81 mg/kg), and roots (236.65 mg/kg). Cr(VI) and PVC MPs-induced inhibition varied with Cr(VI) and PVC MPs doses. Osmolytes and antioxidants, lipid peroxidation, and H2O2 contents were significantly increased, while antioxidant enzymes except CAT were decreased with increasing Cr(VI) concentration alone and mixed treatments. The presence of PVC MPs promoted Cr(VI) accumulation in sweet potato plants, which clearly showed severe toxic effects on their physio-biochemical characteristics, as indicated by a negative correlation between Cr(VI) concentration and these parameters. PVC MPs alone did not significantly inhibit these parameters. The findings of this study provide valuable implications for the proper management of PVC MPs and Cr(VI) in sweet potato plants.

Levels of heavy metal in soil and vegetable and associated health risk in peri-urban areas across China.

Peri-urban vegetable field plays an essential role in providing vegetables for local residents. Because of its particularity, it is affected by both industrial and agricultural activities which have led to the accumulations of heavy metal in soil. So far, information on heavy metal pollution status, spatial features, and human health risks in peri-urban vegetable areas across China is still scarce. To fill this gap, we systematically compiled soil and vegetable data collected from 123 articles published between 2010 and 2022 at a national level. The pollution status of heavy metals (i.e., cadmium (Cd), mercury (Hg), arsenic (As), lead (Pb), chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn)) in peri-urban vegetable soils and vegetables were investigated. To evaluate the levels of heavy metal pollution in soil and human health risks, the geoaccumulation index (Igeo) and target hazard quotient (HQ) were calculated. The results showed that mean concentrations of Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn in peri-urban vegetable soils were 0.50, 0.53, 12.03, 41.97, 55.56, 37.69, 28.55, and 75.38 mg kg-1, respectively. The main pollutants in peri-urban vegetable soil were Cd and Hg, and 85.25% and 92.86% of the soil samples had Igeo > 1, respectively. The mean Igeo values of this regions followed the order of northwest > central > south > north > east > southwest > northeast for Cd and northeast > northwest > north > southwest > east > central > south for Hg. The mean Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn concentrations in vegetables were 0.30, 0.26, 0.37, 0.54, 1.17, 6.17, 1.96, and 18.56 mg kg-1, respectively. Approximately 87.01% (Cd), 71.43% (Hg), 20% (As), 65.15% (Pb), 27.08% (Cr) of the vegetable samples exceeded the safety requirement values. The vegetables grown in central, northwest, and northern China accumulated much more heavy metals than those grown in other regions. As the HQ values for adults, 53.25% (Cd), 71.43% (Hg), 84.00% (As), and 58.33% (Cr) of the sampled vegetables were higher than 1. For children, the HQ values were higher than 1 for 66.23% (Cd), 73.81% (Hg), 86.00% (As), and 87.50% (Cr) of the sampled vegetables. The findings of this study demonstrate that the situation of heavy metal pollution in peri-urban vegetable areas across China are not optimistic and residents who consume the vegetables are at high risk of health issues. To ensure soil quality and human health, strategies should be taken to guide vegetable production and remedy soil pollution in peri-urban areas with the rapidly urbanizing China.

Response of anthocyanin biosynthesis to light by strand-specific transcriptome and miRNA analysis in Capsicum annuum.

BACKGROUND: Anthocyanins have distinct biological functions in plant coloring, plant defense against strong light, UV irradiation, and pathogen infection. Aromatic hydroxyl groups and ortho-dihydroxyl groups in anthocyanins are able to inhibit free-radical chain reactions and hydroxyl radicals. Thus, anthocyanins play an antioxidative role by removing various types of ROS. Pepper is one of the solanaceous vegetables with the largest cultivation area in China. The purple-fruited pepper is rich in anthocyanins, which not only increases the ornamental nature of the pepper fruit but also benefits the human body. In this experiment, light-induced regulatory pathways and related specific regulators of anthocyanin biosynthesis were examined through integrative transcriptomic and metabolomic analysis. RESULTS: Results revealed that delphinium 3-O-glucoside significantly accumulated in light exposed surface of pepper fruit after 48 h as compared to shaded surface. Furthermore, through strand-specific sequencing technology, 1341 differentially expressed genes, 172 differentially expressed lncRNAs, 8 differentially expressed circRNAs, and 28 differentially expressed miRNAs were identified significantly different among both surfaces. The flavonoid synthesis pathway was significantly enriched by KEGG analysis including SHT (XM_016684802.1), AT-like (XM_016704776.1), CCoAOMT (XM_016698340.1, XM_016698341.1), CHI (XM_016697794.1, XM_016697793.1), CHS2 (XM_016718139.1), CHS1B (XM_016710598.1), CYP98A2-like (XM_016688489.1), DFR (XM_016705224.1), F3'5'H (XM_016693437.1), F3H (XM_016705025.1), F3'M (XM_016707872.1), LDOX (XM_016712446.1), TCM (XM_016722116.1) and TCM-like (XM_016722117.1). Most of these significantly enriched flavonoid synthesis pathway genes may be also regulated by lncRNA. Some differentially expressed genes encoding transcription factors were also identified including MYB4-like (XM_016725242.1), MYB113-like (XM_016689220.1), MYB308-like (XM_016696983.1, XM_016702244.1), and EGL1 (XM_016711673.1). Three 'lncRNA-miRNA-mRNA' regulatory networks with sly-miR5303, stu-miR5303g, stu-miR7997a, and stu-miR7997c were constructed, including 28 differentially expressed mRNAs and 6 differentially expressed lncRNAs. CONCLUSION: Possible light regulated anthocyanin biosynthesis and transport genes were identified by transcriptome analysis, and confirmed by qRT-PCR. These results provide important data for further understanding of the anthocyanin metabolism in response to light in pepper.

Chromium Induces Toxicity at Different Phenotypic, Physiological, Biochemical, and Ultrastructural Levels in Sweet Potato (Ipomoea batatas L.) Plants.

Crop productivity is enormously exposed to different environmental stresses, among which chromium (Cr) stress raises considerable concerns and causes a serious threat to plant growth. This study explored the toxic effect of Cr on sweet potato plants. Plants were hydroponically grown, and treatments of 0, 25, 50, 100, and 200 µM Cr were applied for seven days. This study exhibited that a low level of Cr treatment (25 µM) enhanced the growth, biomass, photosynthesis, osmolytes, antioxidants, and enzyme activities. However, significant deleterious effects in growth, biomass, photosynthetic attributes, antioxidants, and enzymes were observed at higher levels of Cr treatment. The remarkable reduction in plant growth traits was associated with the over-accumulation of H2O2 and MDA contents (410% and 577%, respectively) under the highest rate of Cr (200 µM). Under 200 µM Cr, the uptake in the roots were 27.4 mg kg-1 DW, while in shoots were 11 mg kg-1 DW with the highest translocation rate from root to shoot was 0.40. The results showed that the higher accumulation of Cr negatively correlated with the phenotypic and physiological parameters. It may be proposed that Cr toxicity causes oxidative damage as sustained by augmented lipid peroxidation, reactive oxygen species, and reduced photosynthetic rate, chlorophyll, and stomatal traits. The chloroplastic ultrastructure was damaged, and more apparent damage and size reduction were observed at higher Cr levels. Furthermore, aggregated Cr concentration positively correlates with the increase of osmolytes and superoxide dismutase (SOD) activity in the leaves of sweet potato. Moreover, improved osmolytes and SOD do not help protect sweet potato against high Cr stress. Overall, these findings will improve the understanding of the defense mechanisms of sweet potato to Cr stress.

Rapid detection of sweepoviruses through lateral flow dipstick-based recombinase polymerase amplification.

Sweepoviruses represent a phylogenetic group of begomoviruses that cause significant sweet potato (Ipomoea batatas) production losses in various countries across the world. For rapid identification of sweepoviruses, we developed a technique based on isothermal recombinase polymerase amplification in conjunction with lateral flow dipsticks (RPA-LFD). The optimum reaction conditions for the RPA were 20 min incubation at 37°C. The RPA-LFD specifically detected distinct sweepovirus species, with no other viruses infecting sweet potato causing a cross-reaction. The detection limit of the RPA-LFD was 1.0×104 copies of the target DNA molecule per reaction, and it exhibited a 10-fold greater sensitivity than the conventional PCR. Furthermore, when coupled with an alkaline polyethylene glycol-based crude genomic DNA extraction, the entire procedure was completed in 30 min without the use of any special instruments other than a water bath. Therefore, the RPA-LFD technique is a potential sweepovirus diagnostic tool that can be used in the field with fewer available resources. Keywords: detection; sweepoviruses; recombinase polymerase amplification; lateral flow dipstick.

Response of Anthocyanin Accumulation in Pepper (Capsicum annuum) Fruit to Light Days.

Light is the key factor affecting the synthesis of anthocyanins in pepper. In this study, pepper fruit under different light days was used as experimental material to explore the synthesis of anthocyanins in purple pepper. A total of 38 flavonoid metabolites were identified in the purple pepper germplasm HNUCA21 by liquid chromatography-tandem mass spectrometry (LC-MS/MS), of which 30 belong to anthocyanins. The detected anthocyanin with the highest content was Delphinidin-3-O-glucoside (17.13 µg/g), which reached the maximum after 168 h of light treatment. Through weighted gene co-expression network analysis (WGCNA), the brown module was identified to be related to the early synthesis of anthocyanins. This module contains many structural genes related to flavonoid synthesis, including chalcone synthase (CHS 107871256, 107864266), chalcone isomerase (CHI 107871144, 107852750), dihydroflavonol 4-reductase (DFR 107860031), flavonoid 3' 5'-hydroxylase (F3'5'H 107848667), flavonoid 3'-monooxygenase (F3M 107862334), leucoanthocyanidin dioxygenase (LDOX 107866341), and trans-cinnamate 4-monooxygenase (TCM 107875406, 107875407). The module also contained some genes related to anthocyanin transport function, such as glutathione S-transferase (GST 107861273), anthocyanidin 3-O-glucosyltransferase (UDPGT 107861697, 107843659), and MATE (107863234, 107844661), as well as some transcription factors, such as EGL1 (107865400), basic helix-loop-helix 104 (bHLH104 107864591), and WRKY44 (107843538, 107843524). The co-expression regulatory network indicated the involvement of CHS, DFR, CHI, and EGL1, as well as two MATE and two WRKY44 genes in anthocyanin synthesis. The identified genes involved in early, middle, and late light response provided a reference for the further analysis of the regulatory mechanism of anthocyanin biosynthesis in pepper.

Composition, Color Stability and Antioxidant Properties of Betalain-Based Extracts from Bracts of Bougainvillea.

Betalains in bracts of Bougainvillea are of great application potential as natural food colorants and antioxidants. This study explored the color, spectra, composition, storage stability, and antioxidant properties of betalain-based Bougainvillea bracts extracts (BBEs) to verify their application value. The results showed that Bougainvillea bract color variance is due to varied contents and proportions of betacyanins (Bc) and betaxanthins (Bx). Bc or Bx alone determined hues of purple or yellow, respectively; the co-existence of Bc and Bx would produce varied hues of red. BBEs showed bright color and good antioxidant properties under a wide pH range. The pH range of 5−6 was optimal for the highest color stability, and pHs 3−8 were optimal for stronger antioxidants. Bc mainly underwent color fading during storage, while Bx easily produced dark precipitates or melanism under strong acidic (pH < 4) or alkaline conditions (pH > 8). However, Bougainvillea Bx showed 3−4 times higher antioxidant ability than Bc. Different considerations for Bc and Bx are needed for varied application purposes. The purple bracts containing only Bc would be more suitable as colorant sources, while additional Bx can bring enhancement of antioxidant ability and richness of Bougainvillea extract color.

Spectral Characteristic, Storage Stability and Antioxidant Properties of Anthocyanin Extracts from Flowers of Butterfly Pea (Clitoria ternatea L.).

Anthocyanins from flowers of the butterfly pea (Clitoria ternatea L.) are promising edible blue food colorants. Food processing often faces extreme pHs and temperatures, which greatly affects the color and nutritional values of anthocyanins. This study explored the color, spectra, storage stability, and antioxidant properties of C. ternatea anthocyanin extract (CTAE) at different pHs. The color and absorption spectra of CTAEs at a pH of 0.5-13 were shown, with their underlying structures analyzed. Then, the storage stability of CTAEs were explored under a combination of pHs and temperatures. The stability of CTAE declines with the increase in temperature, and it can be stored stably for months at 4 °C. CTAEs also bear much resistance to acidic and alkaline conditions but exhibit higher thermal stability at pH 7 (blue) than at pH 0.5 (magenta) or pH 10 (blue-green), which is a great advantage in food making. Antioxidant abilities for flower extracts from the butterfly pea were high at pH 4-7, as assessed by DPPH free radical scavenging assays, and decreased sharply when the pH value exceeded 7. The above results provide a theoretical basis for the application of butterfly pea flowers and imply their great prospect in the food industry.

Early Response of Radish to Heat Stress by Strand-Specific Transcriptome and miRNA Analysis.

Radish is a crucial vegetable crop of the Brassicaceae family with many varieties and large cultivated area in China. Radish is a cool season crop, and there are only a few heat tolerant radish varieties in practical production with little information concerning the related genes in response to heat stress. In this work, some physiological parameter changes of young leaves under short-term heat stress were detected. Furthermore, we acquired 1802 differentially expressed mRNAs (including encoding some heat shock proteins, heat shock factor and heat shock-related transcription factors), 169 differentially expressed lncRNAs and three differentially expressed circRNAs (novel_circ_0000265, novel_circ_0000325 and novel_circ_0000315) through strand-specific RNA sequencing technology. We also found 10 differentially expressed miRNAs (ath-miR159b-3p, athmiR159c, ath-miR398a-3p, athmiR398b-3p, ath-miR165a-5p, ath-miR169g-3p, novel_86, novel_107, novel_21 and ath-miR171b-3p) by small RNA sequencing technology. Through function prediction and enrichment analysis, our results suggested that the significantly possible pathways/complexes related to heat stress in radish leaves were circadian rhythm-plant, photosynthesis-antenna proteins, photosynthesis, carbon fixation in photosynthetic organisms, arginine and proline metabolism, oxidative phosphorylation, peroxisome and plant hormone signal transduction. Besides, we identified one lncRNA-miRNA-mRNAs combination responsive to heat stress. These results will be helpful for further illustration of molecular regulation networks of how radish responds to heat stress.

A new 2-(2-phenylethyl)chromone glycoside in Chinese agarwood "Qi-Nan" from Aquilaria sinensis.

A new 2-(2-phenylethyl)chromone glycoside, 2-[2-(4-glucosyloxy-3-methoxyphenyl)ethyl]chromone (1), was isolated from the high-quality Chinese agarwood "Qi-Nan" originating from Aquilaria sinensis (Lour.) Glig. The structure including the absolute configuration of the sugar moiety was elucidated by spectroscopic techniques (UV, IR, 1D and 2D NMR), MS analysis, PMP-labeling HPLC analysis methods, as well as comparison with literature data. To the best of our knowledge, it is the first time that chromone glycoside was discovered in agarwood, or even in the whole Aquilaria plants.

2-(2-Phenylethyl)chromone Derivatives of Agarwood Originating from Gyrinops salicifolia.

Three new2-(2-phenylethyl)chromone derivatives (1-3) and a new2-(2-phenylethenyl)chromone derivative (4), together with two known 2-(2-phenylethyl)chromone derivatives (5-6), were isolated from agarwood originating from Gyrinops salicifolia Ridl. The structures of compounds 1-4 were elucidated by comprehensive spectroscopic techniques (UV, IR, 1D and 2D-NMR) and MS analysis, as well as by comparison with the literature. Compounds 1, 2, and 5 showed moderate cytotoxicity against human tumor K562, BEL-7402, and SGC-7901 cell lines with IC50 values of 5.76 to 20.1 µM.

Enhancement of sweetpotato tolerance to chromium stress through melatonin and glutathione: Insights into photosynthetic efficiency, oxidative defense, and growth parameters.

Melatonin (MT) and reduced glutathione (GSH) roles in mitigating chromium (Cr) toxicity in sweetpotato were explored. Plants, pre-treated with varying MT and GSH doses, were exposed to Cr (40 µM). Cr severely hampered growth by disrupting leaf photosynthesis, root system, and oxidative processes and increased Cr absorption. However, the exogenous application of 1 µM of MT and 2 mM of GSH substantially improved growth parameters by enhancing chlorophyll content, gas exchange (Pn, Tr, Gs, and Ci), and chlorophyll fluorescence (Fv/Fm, ETR, qP, and Y(II)). Furthermore, malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide ion (O2•-), electrolyte leakage (EL), and Cr uptake by roots (21.6 and 27.3%) and its translocation to shoots were markedly reduced by MT and GSH application, protecting the cell membrane from oxidative damage of Cr-toxicity. Microscopic analysis demonstrated that MT and GSH maintained chloroplast structure and integrity of mesophyll cells; they also enhanced stomatal length, width, and density, strengthening the photosynthetic system and plant growth and biomass. MT and GSH improved osmo-protectants (proline and soluble sugars), gene expression, and enzymatic and non-enzymatic antioxidant activities, mitigating osmotic stress and strengthening plant defenses under Cr stress. Importantly, the efficiency of GSH pre-treatment in reducing Cr-toxicity surpassed that of MT. The findings indicate that MT and GSH alleviate Cr detrimental effects by enhancing photosynthetic organ stability, component accumulation, and resistance to oxidative stress. This study is a valuable resource for plants confronting Cr stress in contaminated soils, but further field validation and detailed molecular exploration are necessary.

Alleviating sweetpotato salt tolerance through exogenous glutathione and melatonin: A profound mechanism for active oxygen detoxification and preservation of photosynthetic organs.

Salt stress profoundly impacts sweetpotato production. Exogenous glutathione (GSH) and melatonin (MT) promoted plant growth under stress, but their specific roles and mechanisms in sweetpotato salt tolerance need exploration. This study investigated GSH and MT's regulatory mechanisms in sweetpotato under salt stress. Salt stress significantly reduces both growth and biomass by hindering photosynthesis, root traits, K+ content, and K+/Na+ balance, leading to oxidative stress and excessive hydrogen peroxide (H2O2), superoxide ion (O2•-), and malondialdehyde (MDA) production and Na+ accumulation. Nevertheless, GSH (2 mM) and MT (25 µM) pre-treatments effectively mitigated salt-induced oxidative damage and protected the plasma membrane. They reduced osmotic pressure by enhancing K+ uptake, K+/Na+ regulation, osmolyte accumulation, and reducing Na+ accumulation. Improved stomatal traits, chloroplast and grana lamella preservation, and maintenance of mesophyll cells, cell wall, and mitochondrial structure were observed with GSH and MT pre-treatments under salt stress, therefore boosting the photosynthetic system and enhancing plant growth and biomass. Moreover, the findings also indicate that the positive outcomes of GSH and MT pre-treatments result from elevated antioxidant levels, enhanced enzymatic activity, and upregulated expression of sodium hydrogen exchanger 2 (NHX2), K+transporter 1 (AKT1), and cation/H+exchanger (CHX), CBL-interacting protein kinase 1 (CIPK1), and antioxidant enzyme genes. These mechanisms enhance structural stability in photosynthesis and reduce salt stress. Evidently, MT pre-treatment exhibited superior effects compared to GSH. These findings provide a firm theoretical basis for employing GSH and MT to enhance salt tolerance in sweetpotato cultivation.

Pre-Treatment, Extraction Solvent, and Color Stability of Anthocyanins from Purple Sweetpotato.

Purple sweetpotato anthocyanins (PSPA) exhibit significant potential as food colorants with associated health benefits. However, challenges related to browning and instability have hindered the application of PSPA. In this study, various pre-treatments and solvents for PSPA extraction were evaluated based on color, anthocyanin yields, antioxidant capabilities, and brown index. Browning markedly influenced the color and reduced the antioxidant capacity. Optimal results were obtained with the pre-treatment of "steaming of unpeeled whole sweetpotato" and the solvent "1% citric acid-ddH2O". Furthermore, the color stability of purified PSPA solutions was evaluated under pH levels from 1 to 13 at 25 °C and 65 °C. The PSPA solutions showed a color spectrum from magenta, blue/green, and then to yellow across the pH range. The blue/green hues at pH 10-12 rapidly degraded, while the magenta hue at lower pH showed higher color stability. Elevated temperatures significantly accelerated the PSPA degradation. However, PSPA solutions at pH 1-2 exhibited remarkable color stability, with no spectral decay at either 65 °C for 12 h or 25 °C for 32 days. These results provide valid guidance for the extraction, preservation, and application of PSPA in the food industry.

Tracing the vertical migration of exogenous cadmium in soil by seasonal freeze-thaw event using rare earth elements.

Environmental behaviors of heavy metal in soil are strongly influenced by seasonal freeze-thaw events at the mid-high altitudes. However, the potential impact mechanisms of freeze-thaw cycles on the vertical migration of heavy metal are still poor understood. This study aimed to explore how exogenous cadmium (Cd) migrated and remained in soil during the in-situ seasonal freeze-thaw action using rare earth elements (REEs) as tracers. As a comparison, soil which was incubated in the controlled laboratory (25 °C) was employed. Although there was no statistically significant difference in the Cd levels of different soil depths under different treatments, the original aggregate sources of Cd in the 5-10 cm and 10-15 cm soil layers differed. From the distributions of REEs in soil profile, it can be known that Cd in the subsurface of field incubated soil was mainly from the breakdown of >0.50 mm aggregates, while it was mainly from the <0.106 mm aggregates for the laboratory incubated soil. Furthermore, the dissolved and colloidal Cd concentrations were 0.47 µg L-1 and 0.62 µg L-1 in the leachates from field incubated soil than those from control soil (0.21 µg L-1 and 0.43 µg L-1). Additionally, the colloid-associated Cd in the leachate under field condition was mainly from the breakdown of >0.25 mm aggregates and the direct migration of <0.106 mm aggregates, while it was the breakdown of >0.50 mm and the direct migration of <0.106 mm aggregates for the soil under laboratory condition. Our results for the first time provided insights into the fate of exogenous contaminants in seasonal frozen regions using the rare earth element tracing method.

Atrazine decontamination by a newly screened psychrotroph Paenarthrobacter sp. KN0901 in an aquatic system: Metabolic pathway, kinetics, and hydroponics experiment.

Atrazine residues running off the fields and entering water resources are a major threat to food security and the ecosystem. In this study, a psychrotrophic functional strain named KN0901 to remove atrazine residues was screened. KN0901 could degrade 30 mg·L-1 atrazine in 4 days at 15ºC with 105 CFU·mL-1 incubation. The phylogenetic results showed KN0901 belonged to Paenarthrobacter sp. PCR results showed that the functional genes consist of trzN, atzB, and atzC, suggesting atrazine was transformed to cyanuric acid by KN0901. KN0901 could degrade atrazine without adding exogenous carbon and nitrogen sources. What's more, KN0901 could tolerate extreme low temperature (5ºC) and high atrazine concentration (100 mg·L-1). When growth and degradation curves were compared, the results indicated the length of lag time showed significant correlation to atrazine degradation rate. The hydroponic experiments showed that the toxicity of atrazine was significantly reduced with KN0901 treatment. The study provided an effective, economic, and eco-friendly bioremediation measure to address atrazine contamination.

Influence of Planting Density on Sweet Potato Storage Root Formation by Regulating Carbohydrate and Lignin Metabolism.

An appropriate planting density could realize the maximum yield potential of crops, but the mechanism of sweet potato storage root formation in response to planting density is still rarely investigated. Four planting densities, namely D15, D20, D25, and D30, were set for 2-year and two-site field experiments to investigate the carbohydrate and lignin metabolism in potential storage roots and its relationship with the storage root number, yield, and commercial characteristics at the harvest period. The results showed that an appropriate planting density (D20 treatment) stimulated cambium cell differentiation, which increased carbohydrate accumulation and inhibited lignin biosynthesis in potential storage roots. At canopy closure, the D20 treatment produced more storage roots, particularly developing ones. It increased the yield by 10.18-19.73% compared with the control D25 treatment and improved the commercial features by decreasing the storage root length/diameter ratio and increasing the storage root weight uniformity. This study provides a theoretical basis for the high-value production of sweet potato.

The creation of autotetraploid provides insights into critical features of DNA methylome changes after genome doubling in water spinach (Ipomoea aquatica Forsk).

Water spinach (Ipomoea aquatica Forsk) is an essential green leafy vegetable in Asia. In this study, we induced autotetraploid water spinach by colchicine. Furthermore, DNA methylation and transcriptome of tetraploid and diploid were compared using Whole Genome Bisulfite Sequencing (WGBS) and RNA-sequencing techniques. Autotetraploid water spinach was created for the first time. Compared with the diploid parent, autotetraploid water spinach had wider leaves, thicker petioles and stems, thicker and shorter adventitious roots, longer stomas, and larger parenchyma cells. The whole genome methylation level of the autotetraploid was slightly higher than that of the diploid. Compared with the diploid, 12281 Differentially Methylated Regions (DMRs)were found in the autotetraploid, including 2356 hypermethylated and 1310 hypomethylated genes, mainly enriched in 'Arginine and Proline metabolism', 'beta - Alanine metabolism', 'Plant homone signal translation', 'Ribome', and 'Plant - pathgen interaction' pathways. Correlation analysis of transcriptome and DNA methylation data showed that 121 differentially expressed genes undergone differential methylation, related to four pathways 'Other types of O-glycan biosynthesis', 'Terpenoid backbone biosynthesis', 'Biosynthesis of secondary metabolites', and 'Metabolic paths'. This work obtained important autotetraploid resources of water spinach and revealed the genomic DNA methylation changes after genome doubling, being helpful for further studying the molecular mechanism of variations caused by polyploids of the Ipomoea genus.