Here, we evaluated the uptake and biotransformation mechanism of the systemic fungicide phenamacril in hydroponic/soil–plant systems. Phenamacril was preferentially accumulated in shoots with the translocation factor up to 3.5 (or 6.9) in wheat (or rice) during 144 h of the uptake kinetic experiment. Apart from upward xylem translocation, phenamacril could also be redistributed from shoots to roots (0.4%) through phloem transport and then released into the rhizosphere surrounding solution (1.7%) through plant excretion via a split-root experiment. Then, 76.4% (or 70.4%) of phenamacril was transformed to 14 (or 12) metabolites in hydroponic-wheat (or hydroponic-rice) systems after 28 days of exposure, with nine of them first identified based on nontarget analysis. The proposed metabolic pathways included hydroxylation, hydrolysis, isomerization, dehydrogenation, deamination, dehydration, decarboxylation, reduction, and conjugation reactions, which were modulated by genes overexpression of metabolic enzymes (e.g., cytochrome P450). Notably, metabolite M-157 was predicted to be more persistent in environments and more toxic to rats and aquatic organisms than phenamacril by theoretical calculation. This study highlights that phloem transport and plant excretion may result in cycling chemical contamination, and the transformation products may possess elevated toxicities, thus should be considered in estimating the contamination of pesticides in crops and environments.
Growth differentiation factor-8 (GDF-8) is a member of the transforming growth factor-beta superfamily. Studies in vitro and in vivo have shown GDF-8 to be involved in the physiology and pathology of ovarian reproductive functions. In vitro experiments using a granulosa-cell model have demonstrated steroidogenesis, gonadotrophin responsiveness, glucose metabolism, cell proliferation as well as expression of lysyl oxidase and pentraxin 3 to be regulated by GDF-8 via the mothers against decapentaplegic homolog signaling pathway. Clinical data have shown that GDF-8 is expressed widely in the human ovary and has high expression in serum of obese women with polycystic ovary syndrome. GDF-8 expression in serum changes dynamically in patients undergoing controlled ovarian hyperstimulation. GDF-8 expression in serum and follicular fluid is correlated with the ovarian response and pregnancy outcome during in vitro fertilization. Blocking the GDF-8 signaling pathway is a potential therapeutic for ovarian hyperstimulation syndrome and ovulation disorders in polycystic ovary syndrome. GDF-8 has a regulatory role and potential importance in ovarian reproductive activity and may be involved in folliculogenesis, ovulation, and early embryo implantation.
China is the second largest producer of mango in the world, a fruit has high nutritive value and a rich source of fiber (Kuhn et al., 2017). In late June 2019, a postharvest stem-end rot disease was observed in different local fruit markets (39°48'42.1"N 116°20'17.0"E) of the Fengtai district of Beijing, China. Black rot symptomatic lesions were observed on the fruit surface which initially started from the stem end of the mango fruit (Fig. 1). Approximately 45 % of mango fruits were affected with the disease. Symptomatic portions from collected fruit samples (n=40) were cut into small pieces (2mm2), rinsed with 1% NaClO for 20s and then washed three times with sterilized distilled water (SDW) for surface disinfection. The disinfected pieces were then placed on sterilized filter paper for drying. Later, these pieces were placed on Potato Dextrose Agar (PDA) plates and incubated at 28°C for seven days. The resulting fungal colonies were purified by the single spore isolation technique. The isolated fungal colonies were initially greenish to gray in color, later turning olive-black to black. Conidia were dark brown in color, oval-shaped, two-celled and measured 22.4 to 25.7 (24.06 ± 0.15) μm in length and 10.2 to 12.8 (11.3 ± 0.13) μm in width (n=36). Based on the symptoms, culture morphology and microscopic characters, Lasiodiplodia theobromae was suspected as the causal agent, and similar results were reported by Pavlic et al., 2004 and Burgess et al., 2006. For molecular identification, a multi-locus sequence analysis approach was used. The Internal Transcribed Spacers (ITS) region, elongation factor 1 alpha (EF1-α) and β-tubulin genes were amplified and sequenced using ITS1/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn, 1999), and Bt2a/Bt2b (Glass and Donaldson, 1995) primers respectively. The sequences of isolate MFT9 were deposited to GenBank (MW115977 (ITS), (MW118595 (EF1-α) and MW118596 (β-tubulin). All sequences showed more than 99.5% similarity with reported sequences of Lasiodiplodia theobromae isolate IBL340 with accessions numbers KT247466 (ITS), KT247472 (EF1-α) and KT247475 (β-tubulin). Phylogenetic reconstruction based on Maximum Likelihood, using Mega X (Kumar et al., 2018), grouped isolate MFT9 with isolates representing L. theobromae. Pathogenicity testing was performed on 18 fresh, healthy, medium-sized mango fruits for each treatment to fulfill Koch's postulate. The fruits were disinfested with 1% NaClO and punctured with a sterilized needle to create approximately 2mm2 wounds for inoculation. Fruits were inoculated with 15µL of fresh inoculum (107 spores/mL) from isolate MFT9. Control fruits were inoculated with 15µL of SDW and both the inoculated and control fruits were incubated at 28°C for seven days of post inoculation. The rot lesions appeared at the point of inoculation and gradually spread on the fruit surface. The symptoms were similar to the symptoms observed on the original fruit samples (Fig. 2). This experiment was conducted three times under the same conditions, with control fruits remaining asymptomatic each time. The re-isolated fungus was identified as L. theobromae based on symptoms and morpho-molecular analysis, described above. L. theobromae is also reported as a causal agent responsible for a postharvest stem-end rot on Coconut in China (Zhang, et al., 2019). To our knowledge, this is the first report of L. theobromae causing postharvest stem-end rot of mango fruit in China. This finding suggests that L. theobromae is a potential problem for mango fruit production in China.
The effects of different cleanup procedures in removing high-molecular-mass lipids and natural colorants from oil-crop extracts, including dispersive solid-phase extraction, low-temperature precipitation and gel permeation chromatography, were studied. The pigment removal, lipid quantity, and matrix effects of the three cleanup methods were evaluated. Results indicated that the gel permeation chromatography method is the most effective way to compare the dispersive solid-phase extraction and low-temperature precipitation. Pyraclostrobin and epoxiconazole applied extensively in oil-crop production were selected as typical pesticides to study and a trace analytical method was developed by gel permeation chromatography and ultra high performance liquid chromatography with tandem mass spectrometry. Average recoveries of the target pesticides at three levels (10, 50, and 100 μg/kg) were in the range of 74.7-96.8% with relative standard deviation values below 9.2%. The limits of detection did not exceed 0.46 μg/kg, whereas the limits of quantification were below 1.54 μg/kg and much lower than maximum residue limit in all matrices. This study may provide the essential data for optimizing the analytical method of pesticides in oil-crop samples.
Deoxynivalenol (DON) is an important virulence factor of the Fusarium head blight of wheat and threatens the health of humans. The effect of fungicides on DON production after stressing wheat to produce H2O2 and the effect of nontarget pesticides on DON accumulation are largely unknown. Five pesticides were selected to explore the effect of pesticide-induced oxidative stress on DON production in vitro and in vivo. Epoxiconazole and hexaconazole significantly induced an increase in H2O2 in vitro, and H2O2 further stimulated the production of DON and the expression of the Tri5 gene. Imidacloprid, isoproturon, and mesosulfuron-methyl had no direct effect in vitro. All pesticides activated the activities of superoxide dismutase, catalase, and peroxidase in wheat and caused the excessive accumulation of H2O2. However, excessive H2O2 did not stimulate the accumulation of DON. Imidacloprid indirectly stimulated the production of DON in vivo, which may be due to its impact on the secondary metabolism of wheat. In brief, pesticide-induced H2O2 in vitro is an important factor in stimulating DON production, but the stressed physiological H2O2 in wheat is not sufficient to stimulate DON production. The bioaccumulation results indicated that imidacloprid and epoxiconazole increase the risk of DON contamination, especially under field spraying conditions.
The combined use of modified QuEChERS extraction and UHPLC-MS/MS for determining all seven triazolopyrimidine sulfonamide herbicides in cereals (wheat, rice, and corn), soybean and soil was developed.
The distribution behaviour of cyflumetofen in tomatoes during home canning was studied. The targeted compound cyflumetofen was determined by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) after each process step, which included washing, peeling, homogenisation, simmering and sterilisation. Results indicated that more cyflumetofen was removed by washing with detergent solution compared with tap water, 2% NaCl solution and 2% CH3COOH solution. Peeling resulted in 90.2% loss of cyflumetofen and was the most effective step at removing pesticide residues from tomatoes. The processing factors (PFs) of tomato samples after each step were generally less than 1; in particular, the PF of the peeling process for cyflumetofen was 0.28.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)