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Arbuscular mycorrhizal fungi (AMF) play key roles in enhancing plant tolerance to heavy metals, and iron (Fe) compounds can reduce the bioavailability of arsenic (As) in soil, thereby alleviating As toxicity. However, there have been limited studies of the synergistic antioxidant mechanisms of AMF ( Funneliformis mosseae ) and Fe compounds in the alleviation of As toxicity on leaves of maize ( Zea mays L.) with low and moderate As contamination. In this study, a pot experiment was conducted with different concentrations of As (0, 25, 50 mgꞏkg -1 ) and Fe (0, 50 mgꞏkg -1 ) and AMF treatments. Results showed that under low and moderate As concentrations (As25 and As50), the co-inoculation of AMF and Fe compound significantly increased the biomass of maize stems and roots, phosphorus (P) concentration, and P-to-As uptake ratio. Moreover, the co-inoculation of AMF and Fe compound addition significantly reduced the As concentration in stem and root, malondialdehyde (MDA) content in leaf, and soluble protein and non-protein thiol (NPT) contents in leaf of maize under As25 and As50 treatments. In addition, co-inoculation with AMF and Fe compound addition significantly increased the activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) in the leaves of maize under As25 treatment. Correlation analysis showed that stem biomass and leaf MDA content were very significantly negatively correlated with stem As content, respectively. In conclusion, the results indicated that the co-inoculation of AMF and Fe compound addition can inhibit As uptake and promote P uptake by maize under low and moderate As contamination, thereby mitigating the lipid peroxidation on maize leaves and reducing As toxicity by enhancing the activities of antioxidant enzymes under low As contamination. These findings provide a theoretical basis for the application of AMF and Fe compounds in the restoration of cropland soil contaminated with low and moderate As.

To investigate the dominant plants in ecological restoration of tin mining areas, field investigations were conducted in a tin tailings area in Lailishan, Yunnan Provence, and 15 dominant plants and corresponding rhizosphere soils were collected. The plant root mycorrhizal infection rate; the copper (Cu), cadmium (Cd), arsenic (As), nickel (Ni), lead (Pb), and tin (Sn) contents; and the chemical properties of the rhizosphere tailings were determined. The transfer and enrichment coefficients of six heavy metals were calculated for each of the 15 plants to comprehensively evaluate the application potential of native plants. The rhizophere tailings had an average pH value of 3.13, which was acidic. The organic matter, total nitrogen, total phosphorus, total potassium, alkaline hydrolyzed nitrogen, and available phosphorus content of the soils was 6.07 g ·kg -1 , 5.74 g ·kg -1 , 0.62 g ·kg -1 , 8.66 g ·kg -1 , 30.84 mg ·kg -1 , and 2.08 mg ·kg -1 respectively, indicating relatively nutrient-poor soil. The average Cu, Cd, Ni, Pb, As, and Sn contents of the soils were 347.40, 1.02, 1.34, 168.47, 25.81, and 2299.02 mg ·kg -1 , respectively. Among the heavy metals, the Cd content reached a third-level pollution warning value. The soil also contained a large amount of Cu and Pb which exhibited a different spatial distribution. This area appears to have a high risk of Cu, Pb, and Cd pollution. In addition, the roots of Olea europaea L. and Eurya japonica Thunb. had a high rate of mycorrhizal infection. Alnus cremastogyne Burk., Bambusa multiplex (Lour.) Raeusch. ex Schult. 'Alphonse-Kar' R. A. Young, Juncus effusus L., and Cyperus rotundus L. var . had a strong ability to absorb and transport heavy metals. The other plants were also adapted to the growth environment of the tin tailings, with the potential to restore the mining area.

We sequenced and assembled eight complete plastid genomes from three closely related pleurocarpous moss families: Amblystegium serpens , Campyliadelphus stellatus , Cratoneuron filicinum , Drepanocladus aduncus , and Leptodictyum humile (Amblystegiaceae), Calliergon sarmentosum and Warnstorfia exannulata (Calliergonaceae), and Calliergonella cuspidata (Pylaisiaceae). The newly generated plastid genomes range from 124,256 to 124,819 bp, with two inverted repeat regions (9,624-9,696 bp) separated by a large single-copy region (86,422-86,924 bp) and a small single-copy region (18,430-18,514 bp). All these plastid genomes encode 116 unique genes including 82 protein-coding genes, 30 tRNA genes and four rRNAgenes. The overall GC content is between 28.6%-29.3%. Phylogenetic analysis showed that all Amblystegiaceae species Amblystegium serpens , Campyliadelphus stellatus , Cratoneuron filicinum , Drepanocladus aduncus , Leptodictyum humile , and Sanionia uncinata clustered in one clade, which is sister to the Pylaisiaceae species Calliergonella cuspidata . The two Calliergonaceae species Calliergon sarmentosum and Warnstorfia exannulata form a clade and is sister to Amblystegiaceae and Pylaisiaceae., Competing Interests: The authors declare no conflicts of insterest., (© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Background: Insects cannot synthesize sterols and must acquire them from food. The mechanisms underlying how insects uptake dietary sterols are largely unknown except that NPC1b, an integral membrane protein, has been shown to be responsible for dietary cholesterol uptake in Drosophila melanogaster. However, whether NPC1b orthologs in other insect species, particularly the economically important pests, function similarly remains to be determined., Results: In this study, we characterized the function of NPC1b in Helicoverpa armigera, a global pest that causes severe yield losses to many important crops. Limiting dietary cholesterol uptake to insects significantly inhibited food ingestion and weight gain. Compared to the wild-type H. armigera, the CRISPR/Cas9-edited NPC1b mutant larvae were incapable of getting adequate cholesterol and died in their early life stage. Gene expression profile and in situ hybridization analyses indicated that NPC1b was mainly expressed in the midgut where dietary cholesterol was absorbed. Expression of NPC1b was also correlated with the feeding life stages and was especially upregulated during early larval instars. Protein-ligand docking and sequence similarity analyses further demonstrated that NPC1b proteins of lepidopteran insects shared a relatively conserved cholesterol binding region, NPC1b_NTD, which, however, was highly divergent from bees-derived sequences., Conclusion: NPC1b was crucial for dietary cholesterol uptake and growth of H. armigera, and therefore could serve as an insecticide target for the development of a novel pest-management approach to control this economically significant insect pest with little off-target effect on bees and sterol-autotrophic animals. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Sterols are essential nutrients for eukaryotes. Insects are obligate sterol auxotrophs and must acquire this key nutrient from their diets. The digestive tract is the organ for absorbing nutrients as well as sterols from food. In mice, the Niemann-Pick type C1 Like 1 (NPC1L1) gene is highly expressed in the intestine and is critical for cholesterol absorption. In contrast, the molecular mechanisms for the absorption of dietary sterols in insects have not been well studied. We annotated NPC1 genes in 39 insects from 10 orders using available genomic and transcriptomic information and inferred phylogenetic relationships. Insect NPC1 genes were grouped into two sister-clades, NPC1a and NPC1b, suggesting a likely duplication in the ancestor of insects. The former exhibited weaker gut-biased expression or a complete lack of tissue-biased expression, depending on the species, while the latter was highly enriched in the gut of three lepidopteran species. This result is similar to previous findings in Drosophila melanogaster. In insects, NPC1a accumulated non-synonymous substitutions at a lower rate than NPC1b. This pattern was consistent across orders, indicating that NPC1a evolved under stronger molecular constraint than NPC1b., (Copyright © 2018 Elsevier Ltd. All rights reserved.)