Organic Acid Excretion in Root Exudates as a Mechanism of Cadmium Uptake in a Sonchus Asper-Zea Mays Intercropping System.

This study assessed how the Sonchus asper L.-Zea mays intercropping influenced the plant Cd level, as well as the organic acid (low molecular mass) types and concentrations in root secretions, which was accomplished by conducting pot experiments with soil that was collected from a farmland surrounding a mining area. The results showed that the oxalic and citric acids were the prevailing organic acids in the plant root secretions, and that the intercropping led to prominently elevated root exudate concentrations of the two acids for S. asper by 43.8 and 75.4%, respectively, while decreased such concentrations by 18.5 and 18.7% for Z. mays, compared to monoculture. According to observations, the root exudate concentrations of citric and oxalic acids were significantly positively related to the available rhizosphere soil Cd and plant Cd. The results indicate that changes in root exudation of oxalic acid and citric acid result in different available Cd contents of the rhizosphere soil, thereby affecting the bioavailability of soil Cd, which increases Cd uptake and accumulation in S. asper but inhibits Cd accumulation in Z. mays.

First Report of Leaf Spot Caused by Alternaria alternata on Sonchus asper in China.

Sonchus asper (Spiny sowthistle), belonging to the Asteraceae, is a problematic weed in grain crops, orchards as well as turf (Cho et al., 2019). In April 2016, about 90% of the S. asper plants infesting a pear orchard had symptomatic with black spots densely distributed on the leaves and stems in Da Yang Town, Luyang District, Hefei, Anhui (N31°55'43″, E117°11'40″). The foliar lesions were mostly circular (3.0 mm to 1.5 cm in diameter) or irregular in shape; lesions on the stem were elliptical to irregular in shape running along the vascular bundle and about 3 to 6mm long × 2 to 3mm wide. Severely affected plants had their leaves become completely blighted and eventually the plants died. Fifteen tissue pieces from five symptomatic leaves and stems were surface sterilized with 0.5% NaClO for two min, rinsed three times with sterile water, and then plated on 1/4-strength potato dextrose agar (PDA) medium. Fourteen fungal isolated were obtained from the tissues, the isolation frequency from the plant tissue pieces was almost 93%. Fungal colonies were circular, initially white, and eventually turned to dark olive or black along with profuse sporulation. The conidia were tawny to brownish green, obclavate to obpyriform, with a cylindrical or coniform short beak, ranging from 16.8 to 39.8 µm long × 6.3 to 14.7 µm wide with two to five transverse and zero to two longitudinal septa (n = 50) and were borne on branched conidiophores. These morphological characteristics were similar to those described for Alternaria alternata (Simmons, 2007). For one representative isolate, the internal transcribed spacer (ITS) region of rDNA, partial coding sequence of the actin (ACT) gene, partial Alt a 1 major allergen (ALT) gene and partial Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene were amplified and sequenced with primers ITS1/ITS4 (White et al., 1990), ACT512F/ACT783R (Carbone and Kohn, 1999), Alt-4for/Alt-4rev and gpd1/gpd2 (Lawrence et al., 2013) respectively. Sequences were submitted to GenBank (ITS: MH886523; ACT: MH892480; ALT: MN655781; GAPDH: MN655782). Based on a BLAST analysis, ITS, ACT gene and GAPDH gene had 100%-99.8% identity with the existing sequences of the ex-type CBS 916.96 of A. alternata (Fries) Keissler (ITS: AF347031; ACT: JQ671702; GAPDH: AY278808, respectively) and ALT gene showed 100% identity with the A. alternata isolate SCWC10 (MG199093). Thus the pathogen was identified as A. alternata based on its morphological and molecular characteristics. Pathogenicity tests were conducted on six to seven-leaf stage potted S. asper plants (one plant per pot). Five mm diameter fungal disks, which were excised from the edge of a three-day old A. alternata colony, were placed on healthy leaves of five plants. Same size sterile PDA disks were used as controls. In addition, a conidial suspension (107 conidia/ml) was also inoculated on healthy leaves of five plants, sterile distilled water was used as control. Both inoculation experiments were conducted in the greenhouse at 25 ± 2°C, 90 % relative humidity, 12 h light/dark photoperiod and repeated at least three times. Lesions were observed on all the leaves within 12 h after fungal disk inoculation. All pathogen inoculated plants developed lesions, similar to those observed on the symptomatic leaves in the field 12 days after conidial inoculation. No symptoms were observed on both control treatments. A. alternata was re-isolated from the inoculated leaves and confirmed by both morphological and molecular techniques, confirming Koch's postulates. To our knowledge, this is the first report of A. alternata causing leaf spot on S. asper in China. The pathogen could cause severe disease in S. asper, and has the potential to be further studied as a fungal weed biocontrol.

Modulation of carbon tetrachloride-induced nephrotoxicity in rats by n-hexane extract of Sonchus asper.

Sonchus asper is traditionally used in the treatment of renal dysfunction. In the present study, protective effects of S. asper against carbon tetrachloride (CCl4)-induced nephrotoxicity of rats were determined. In this study, 24 male albino rats (190-200 g) were equally divided into four groups. Group I (control group) was given saline (1 ml/kg body weight (b.w.), 0.85% NaCl) and dimethyl sulfoxide (1 ml/kg b.w.); group II was treated with CCl4 (1 ml/kg b.w. intraperitoneally); groups III and IV were administered with CCl4 and after 48 h with S. asper n-hexane extract (SHE; 100 and 200 mg/kg b.w.). All the treatments were given twice a week for 4 weeks. The results revealed that CCl4-induced oxidative stress as evidenced by the significant depletion of antioxidant enzymes, namely, superoxide dismutase, catalase, peroxidase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase, and glutathione contents, while increased lipid peroxidation (thiobarbituric acid-reactive substances contents). Administration of SHE significantly ameliorated (p < 0.01) the activity of antioxidant enzymes and reduced lipid peroxides. Coadministration revealed that S. asper extract can protect the kidney against CCl4-mediated oxidative damage by restoring the activity of antioxidant enzyme, due to the presence of plant bioactive constituents.

Root-associated microbiota drive phytoremediation strategies to lead of Sonchus Asper (L.) Hill as revealed by intercropping-induced modifications of the rhizosphere microbiome.

Intercropping or assistant endophytes promote phytoremediation capacities of hyperaccumulators and enhance their tolerance to heavy metal (HM) stress. Findings from a previous study showed that intercropping the hyperaccumulator Sonchus asper (L.) Hill grown in HM-contaminated soils with maize improved the remediating properties and indicated an excluder-to-hyperaccumulator switched mode of action towards lead. In the current study, RNA-Seq analysis was conducted on Sonchus roots grown under intercropping or monoculture systems to explore the molecular events underlying this shift in lead sequestering strategy. The findings showed that intercropping only slightly affects S. asper transcriptome but significantly affects expression of root-associated microbial genomes. Further, intercropping triggers significant reshaping of endophytic communities associated with a 'root-to-shoot' transition of lead sequestration and improved phytoremediation capacities of S. asper. These findings indicate that accumulator activities of a weed are partially attributed to the root-associated microbiota, and a complex network of plant-microbe-plant interactions shapes the phytoremediation potential of S. asper. Analysis showed that intercropping may significantly change the structure of root-associated communities resulting in novel remediation properties, thus providing a basis for improving phytoremediation practices to restore contaminated soils.

Sow Thistle Chloroplast Genomes: Insights into the Plastome Evolution and Relationship of Two Weedy Species, Sonchus asper and Sonchus oleraceus (Asteraceae).

Prickly sow thistle, Sonchus asper (L.) Hill, and common sow thistle, Sonchus oleraceus L., are noxious weeds. Probably originating from the Mediterranean region, they have become widespread species. They share similar morphology and are closely related. However, they differ in their chromosome numbers and the precise relationship between them remains uncertain. Understanding their chloroplast genome structure and evolution is an important initial step toward determining their phylogenetic relationships and analyzing accelerating plant invasion processes on a global scale. We assembled four accessions of chloroplast genomes (two S. asper and two S. oleraceus) by the next generation sequencing approach and conducted comparative genomic analyses. All the chloroplast genomes were highly conserved. Their sizes ranged from 151,808 to 151,849 bp, containing 130 genes including 87 coding genes, 6 rRNA genes, and 37 tRNA genes. Phylogenetic analysis based on the whole chloroplast genome sequences showed that S. asper shares a recent common ancestor with S. oleraceus and suggested its likely involvement in a possible amphidiploid origin of S. oleraceus. In total, 79 simple sequence repeats and highly variable regions were identified as the potential chloroplast markers to determine genetic variation and colonization patterns of Sonchus species.

Assessment of chromium hyper-accumulative behaviour using biochemical analytical techniques of greenhouse cultivated Sonchus asper on tannery waste dump site soils.

Keeping the sources of pollution such as chromium (Cr) under a safe limit is a daunting challenge due to the negative impact of heavy metal bioaccumulation in vegetation and the concomitant human health exposure. We took a closer look at Sonchus asper by cultivating in the green house. It resulted in 80% germination when cultivated over nine different soils collected from the tannery dump site. The biochemical analytical techniques such as mass spectrometry indicated significant bioaccumulation of Cr in the plant tissue. As per the ICP-MS analysis, this annual herb resulted in the accumulation of 601 mg kg-1 of total Cr with 212 mg kg-1 in its shoot from soil samples containing up to 41 mg kg-1 of hexavalent Cr. The energy dispersive X-ray (EDX) spectroscopy of S. asper revealed a higher level of S element indicating a sulfate-Cr binding relation. Elevated content of Cr in soil (73,721 ± 65 mg kg-1) caused biochemical changes in the shoot of S. asper as indicated by the disappearance of Fourier transform infrared spectroscopy (FTIR) bands at 935 and 872 cm-1 and further revealing aliphatic -CH2 appearing as anti-symmetry νa(CH2) and symmetric vibration νs(CH2) at the band of 2920 and 2850 cm-1, respectively.

Sonchus asper extract inhibits LPS-induced oxidative stress and pro-inflammatory cytokine production in RAW264.7 macrophages.

BACKGROUND/OBJECTIVES: Sonchus asper is used extensively as an herbal anti-inflammatory for treatment of bronchitis, asthma, wounds, burns, and cough; however, further investigation is needed in order to understand the underlying mechanism. To determine its mechanism of action, we examined the effects of an ethyl acetate fraction (EAF) of S. asper on nitric oxide (NO) production and prostaglandin-E2 levels in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. MATERIALS/METHODS: An in vitro culture of RAW264.7 macrophages was treated with LPS to induce inflammation. RESULTS: Treatment with EAF resulted in significant suppression of oxidative stress in RAW264.7 macrophages as demonstrated by increased endogenous superoxide dismutase (SOD) activity and intracellular glutathione levels, decreased generation of reactive oxygen species and lipid peroxidation, and restoration of the mitochondrial membrane potential. To confirm its anti-inflammatory effects, analysis of expression of inducible NO synthase, cyclooxygenase-2, tumor necrosis factor-α, and the anti-inflammatory cytokines IL-1ß and IL-6 was performed using semi-quantitative RT-PCR. EAF treatment resulted in significantly reduced dose-dependent expression of all of these factors, and enhanced expression of the antioxidants MnSOD and heme oxygenase-1. In addition, HPLC fingerprint results suggest that rutin, caffeic acid, and quercetin may be the active ingredients in EAF. CONCLUSIONS: Taken together, findings of this study imply that the anti-inflammatory effect of EAF on LPS-stimulated RAW264.7 cells is mediated by suppression of oxidative stress.

Sonchus asper extract inhibits LPS-induced oxidative stress and pro-inflammatory cytokine production in RAW264.7 macrophages

BACKGROUND/OBJECTIVES: Sonchus asper is used extensively as an herbal anti-inflammatory for treatment of bronchitis, asthma, wounds, burns, and cough; however, further investigation is needed in order to understand the underlying mechanism. To determine its mechanism of action, we examined the effects of an ethyl acetate fraction (EAF) of S. asper on nitric oxide (NO) production and prostaglandin-E2 levels in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. MATERIALS/METHODS: An in vitro culture of RAW264.7 macrophages was treated with LPS to induce inflammation. RESULTS: Treatment with EAF resulted in significant suppression of oxidative stress in RAW264.7 macrophages as demonstrated by increased endogenous superoxide dismutase (SOD) activity and intracellular glutathione levels, decreased generation of reactive oxygen species and lipid peroxidation, and restoration of the mitochondrial membrane potential. To confirm its anti-inflammatory effects, analysis of expression of inducible NO synthase, cyclooxygenase-2, tumor necrosis factor-alpha, and the anti-inflammatory cytokines IL-1beta and IL-6 was performed using semi-quantitative RT-PCR. EAF treatment resulted in significantly reduced dose-dependent expression of all of these factors, and enhanced expression of the antioxidants MnSOD and heme oxygenase-1. In addition, HPLC fingerprint results suggest that rutin, caffeic acid, and quercetin may be the active ingredients in EAF. CONCLUSIONS: Taken together, findings of this study imply that the anti-inflammatory effect of EAF on LPS-stimulated RAW264.7 cells is mediated by suppression of oxidative stress.