Abstract: The use of nitrification inhibitors has been suggested as a strategy to decrease cadmium (Cd) accumulation in crops. However, the most efficient nitrification inhibitor for mitigating crop Cd accumulation remains to be elucidated, and whether and how changes in soil microbial structure are involved in this process also remains unclear. To address these questions, this study applied three commercial nitrification inhibitors, namely, dicyandiamide (DCD), 3,4-dimethylpyrazole phosphate (DMPP), and nitrapyrin (NP), to pakchoi. The results showed that both DCD and DMPP (but not NP) could efficiently decrease Cd concentrations in pakchoi in urea- and ammonium-fertilized soils. In addition, among the three tested nitrification inhibitors, DMPP was the most efficient in decreasing the Cd concentration in pakchoi. The nitrification inhibitors decreased pakchoi Cd concentrations by suppressing acidification-induced Cd availability and reshaping the soil microbial structure; the most effective nitrification inhibitor was DMPP. Ammonia oxidation generates the most protons during nitrification and is inhibited by nitrification inhibitors. Changes in environmental factors and predatory bacterial abundance caused by the nitrification inhibitors changed the soil microbial structure and increased the potential participants in plant Cd accumulation. In summary, our study identified DMPP as the most efficient nitrification inhibitor for mitigating crop Cd contamination and observed that the soil microbial structural changes caused by the nitrification inhibitors contributed to decreasing Cd concentration in pakchoi.

减控小青菜镉污染的高效硝化抑制剂筛选及其微生物学机制研究

[1]AghnatiosR, DrancourtM, 2016. Gemmata species: planctomycetes of medical interest. Future Microbiol, 11(5):659-667.

[2]AmooAE, BabalolaOO, 2017. Ammonia-oxidizing microorganisms: key players in the promotion of plant growth. J Soil Sci Plant Nutr, 17(4):935-947.

[3]BaoSD, 2000. Soil Agricultural Chemistry Analysis, 3rd Ed. China Agriculture Press, Beijing, China(in Chinese).

[4]BolyenE, RideoutJR, DillonMR, et al., 2019. Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2. Nat Biotechnol, 37(8):852-857.

[5]CarneiroJ, CardenasLM, HatchDJ, et al., 2010. Effect of the nitrification inhibitor dicyandiamide on microbial communities and N₂O from an arable soil fertilized with ammonium sulphate. Environ Chem Lett, 8(3):237-246.

[6]ChenH, JiangW, 2014. Application of high-throughput sequencing in understanding human oral microbiome related with health and disease. Front Microbiol, 5:508.

[7]ChenYM, DingQB, ChaoYQ, et al., 2018. Structural development and assembly patterns of the root-associated microbiomes during phytoremediation. Sci Total Environ, 644:1591-1601.

[8]ClemensS, AartsMGM, ThomineS, et al., 2013. Plant science: the key to preventing slow cadmium poisoning. Trends Plant Sci, 18(2):92-99.

[9]CuiL, LiDP, WuZJ, et al., 2021. Effects of nitrification inhibitors on soil nitrification and ammonia volatilization in three soils with different pH. Agronomy, 11(8):1674.

[10]DheriGS, Singh BrarM, MalhiSS, 2007. Influence of phosphorus application on growth and cadmium uptake of spinach in two cadmium‐contaminated soils. J Plant Nutr Soil Sci, 170(4):495-499.

[11]DiHJ, CameronKC, 2004. Effects of temperature and application rate of a nitrification inhibitor, dicyandiamide (DCD), on nitrification rate and microbial biomass in a grazed pasture soil. Soil Res, 42(8):927-932.

[12]DongJ, MaoWH, ZhangGP, et al., 2007. Root excretion and plant tolerance to cadmium toxicity ‒ a review. Plant Soil Environ, 53(5):193-200.

[13]DongZ, LayzellDB, 2001. H₂ oxidation, O₂ uptake and CO₂ fixation in hydrogen treated soils. Plant Soil, 229(1):1-12.

[14]DongZ, WuL, KettlewellB, et al., 2003. Hydrogen fertilization of soils ‒ is this a benefit of legumes in rotation? Plant Cell Environ, 26(11):1875-1879.

[15]GillSR, PopM, DeBoyRT, et al., 2006. Metagenomic analysis of the human distal gut microbiome. Science, 312(5778):1355-1359.

[16]GuanMY, FanSK, FangXZ, et al., 2015. Modification of nitrate uptake pathway in plants affects the cadmium uptake by roots. Plant Signal Behav, 10(3):e990794.

[17]JacksonAP, AllowayBJ, 1991. The bioavailability of cadmium to lettuce and cabbage in soils previously treated with sewage sludges. Plant Soil, 132(2):179-186.

[18]JungMY, SedlacekCJ, KitsKD, et al., 2022. Ammonia-oxidizing archaea possess a wide range of cellular ammonia affinities. ISME J, 16(1):272-283.

[19]KelliherFM, CloughTJ, ClarkH, et al., 2008. The temperature dependence of dicyandiamide (DCD) degradation in soils: a data synthesis. Soil Biol Biochem, 40(7):1878-1882.

[20]KirkhamMB, 2006. Cadmium in plants on polluted soils: effects of soil factors, hyperaccumulation, and amendments. Geoderma, 137(1-2):19-32.

[21]KitsKD, SedlacekCJ, LebedevaEV, et al., 2017. Kinetic analysis of a complete nitrifier reveals an oligotrophic lifestyle. Nature, 549(7671):269-272.

[22]KleineidamK, KošmrljK, KublikS, et al., 2011. Influence of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on ammonia-oxidizing bacteria and archaea in rhizosphere and bulk soil. Chemosphere, 84(1):182-186.

[23]LeiboldMA, McPeekMA, 2006. Coexistence of the niche and neutral perspectives in community ecology. Ecology, 87(6):1399-1410.

[24]LewisKA, TzilivakisJ, WarnerDJ, et al., 2016. An international database for pesticide risk assessments and management. Human Ecol Risk Assess: An Int J, 22(4):1050-1064.

[25]LiHF, AbbasT, CaiM, et al., 2021. Cd bioavailability and nitrogen cycling microbes interaction affected by mixed amendments under paddy-pak choi continued planting. Environ Pollut, 275:116542.

[26]LiYC, JiangJQ, ZhangLD, et al., 2023. Impact and its mechanism of alkaline functional fertilizer on cadmium activity in soil. J Soils Sediments, 23(11):399

[27]LinJH, LiHX, HuF, et al., 2004. Effects of rewetting on soil biota structure and nitrogen mineralization, nitrification in air-dried red soil. Acta Pedol Sin, 41(6):924-930 (in Chinese).

[28]LiuJJ, ZhangDZ, ZhangYB, et al., 2023. Regulatory effects of selenium and tellurium on alleviating cadmium toxicity and reducing grain cadmium accumulation in broomcorn millet (Panicum miliaceum). Chin Bull Bot, 58(1):62-76 (in Chinese).

[29]LoucaS, ParfreyLW, DoebeliM, 2016. Decoupling function and taxonomy in the global ocean microbiome. Science, 353(6305):1272-1277.

[30]LuoBF, DuST, LuKX, et al., 2012. Iron uptake system mediates nitrate-facilitated cadmium accumulation in tomato (Solanum lycopersicum) plants. J Exp Bot, 63(8):3127-3136.

[31]LuxA, MartinkaM, VaculíkM, et al., 2011. Root responses to cadmium in the rhizosphere: a review. J Exp Bot, 62(1):21-37.

[32]MacadamXMB, del PradoA, MerinoP, et al., 2003. Dicyandiamide and 3,4-dimethyl pyrazole phosphate decrease N₂O emissions from grassland but dicyandiamide produces deleterious effects in clover. J Plant Physiol, 160(12):1517-1523.

[33]MaoQQ, GuanMY, LuKX, et al., 2014. Inhibition of nitrate transporter 1.1-controlled nitrate uptake reduces cadmium uptake in Arabidopsis. Plant Physiol, 166(2):934-944.

[34]Martens-HabbenaW, BerubePM, UrakawaH, et al., 2009. Ammonia oxidation kinetics determine niche separation of nitrifying Archaea and Bacteria. Nature, 461(7266):976-979.

[35]MengDL, LiJ, LiuTB, et al., 2019. Effects of redox potential on soil cadmium solubility: insight into microbial community. J Environ Sci, 75:224-232.

[36]NazarR, IqbalN, MasoodA, et al., 2012. Cadmium toxicity in plants and role of mineral nutrients in its alleviation. Am J Plant Sci, 3(10):1476-1489.

[37]O'CallaghanM, GerardEM, CarterPE, et al., 2010. Effect of the nitrification inhibitor dicyandiamide (DCD) on microbial communities in a pasture soil amended with bovine urine. Soil Biol Biochem, 42(9):1425-1436.

[38]PapadopoulouES, BachtsevaniE, LampronikouE, et al., 2020. Comparison of novel and established nitrification inhibitors relevant to agriculture on soil ammonia- and nitrite-oxidizing isolates. Front Microbiol, 11:581283.

[39]PasternakZ, PietrokovskiS, RotemO, et al., 2013. By their genes ye shall know them: genomic signatures of predatory bacteria. ISME J, 7(4):756-769.

[40]PérezJ, Moraleda-MuñozA, Marcos-TorresFJ, et al., 2016. Bacterial predation: 75 years and counting! Environ Microbiol, 18(3):766-779.

[41]Piché-ChoquetteS, ConstantP, 2019. Molecular hydrogen, a neglected key driver of soil biogeochemical processes. Appl Environ Microbiol, 85(6):e02418-18.

[42]QuastC, PruesseE, YilmazP, et al., 2013. The SILVA ribosomal RNA gene database project: improved data processing and web-based tools. Nucleic Acids Res, 41(D1):D590-D596.

[43]RognesT, FlouriT, NicholsB, et al., 2016. VSEARCH: a versatile open source tool for metagenomics. PeerJ, 4:e2584.

[44]RyanJA, PahrenHR, LucasJB, 1982. Controlling cadmium in the human food chain: a review and rationale based on health effects. Environ Res, 28(2):251-302.

[45]SarwarN, Saifullah, MalhiS, et al., 2010. Role of mineral nutrition in minimizing cadmium accumulation by plants. J Sci Food Agric, 90(6):925-937.

[46]SatarugS, GarrettSH, SensMA, et al., 2010. Cadmium, environmental exposure, and health outcomes. Environ Health Perspect, 118(2):182-190.

[47]SchaeferHR, DennisS, FitzpatrickS, 2020. Cadmium: mitigation strategies to reduce dietary exposure. J Food Sci, 85(2):260-267.

[48]SchaussK, FocksA, LeiningerS, et al., 2009. Dynamics and functional relevance of ammonia-oxidizing archaea in two agricultural soils. Environ Microbiol, 11(2):446-456.

[49]SegataN, IzardJ, WaldronL, et al., 2011. Metagenomic biomarker discovery and explanation. Genome Biol, 12(6):1-18.

[50]ShahidM, JavedMT, MushtaqA, et al., 2019. Microbe-mediated mitigation of cadmium toxicity in plants. In: Hasanuzzaman M, Prasad MNV, Fujita M (Eds.), Cadmium Toxicity and Tolerance in Plants: From Physiology to Remediation. Academic Press, Amsterdam, p.427-449.

[51]SheJY, WangJ, WeiXD, et al., 2021. Survival strategies and dominant phylotypes of maize-rhizosphere microorganisms under metal(loid)s contamination. Sci Total Environ, 774:145143.

[52]ShiRY, NiN, NkohJN, et al., 2019. Beneficial dual role of biochars in inhibiting soil acidification resulting from nitrification. Chemosphere, 234:43-51.

[53]ShiXZ, HuHW, MüllerC, et al., 2016. Effects of the nitrification inhibitor 3,4-dimethylpyrazole phosphate on nitrification and nitrifiers in two contrasting agricultural soils. Appl Environ Microbiol, 82(17):5236-5248.

[54]SinghPP, PriyamA, SinghJ, et al., 2023. Biologically synthesised urea-based nanomaterial shows enhanced agronomic benefits in maize and rice crops during Kharif season. Sci Hortic, 315:111988.

[55]SinghS, RathvaHK, SahayT, et al., 2020. Gemmata obscuriglobus: a connecting link between prokaryotic and eukaryotic cell. Biologia, 75(12):2433-2439.

[56]SmoldersE, 2001. Cadmium uptake by plants. Int J Occup Med Environ Health, 14(2):177-183.

[57]Souza-ArroyoV, FabiánJJ, Bucio-OrtizL, et al., 2022. The mechanism of the cadmium-induced toxicity and cellular response in the liver. Toxicology, 480:153339.

[58]SteinS, SelesiD, SchillingR, et al., 2005. Microbial activity and bacterial composition of H₂-treated soils with net CO₂ fixation. Soil Biol Biochem, 37(10):1938-1945.

[59]VilsmeierK, 1980. Effect of temperature on the breakdown of dicyandiamide in the soil. Z Pflanzenernahrung Bodenkunde, 143(1):113-118.

[60]WangGB, ZhangQQ, DuWC, et al., 2021. Microbial communities in the rhizosphere of different willow genotypes affect phytoremediation potential in Cd contaminated soil. Sci Total Environ, 769:145224.

[61]WangXW, LiuT, ChuGX, 2017. Inhibition of DCD, DMPP and nitrapyrin on soil nitrification and their appropriate use dosage. J Plant Nutr Fert, 23(1):54-61 (in Chinese).

[62]WitteCP, 2011. Urea metabolism in plants. Plant Sci, 180(3):431-438.

[63]WoltJD, 2000. Nitrapyrin behavior in soils and environmental considerations. J Environ Qual, 29(2):367-379.

[64]XieHL, JiangRF, ZhangFS, et al., 2009. Effect of nitrogen form on the rhizosphere dynamics and uptake of cadmium and zinc by the hyperaccumulator Thlaspi caerulescens. Plant Soil, 318(1-2):205-215.

[65]YangYJ, XiongJ, TaoLX, et al., 2020. Regulatory mechanisms of nitrogen (N) on cadmium (Cd) uptake and accumulation in plants: a review. Sci Total Environ, 708:135186.

[66]YouY, WuCN, ZhongWJ, et al., 2020. Effects of dicyandiamide on cadmium accumulation in pakchoi under instant soluble nitrogen fertilizers. Chin J Appl Ecol, 31(9):3093-3100 (in Chinese).

[67]YuHY, LiuCP, ZhuJS, et al., 2016. Cadmium availability in rice paddy fields from a mining area: the effects of soil properties highlighting iron fractions and pH value. Environ Pollut, 209:38-45.

[68]YuanQS, WangPF, WangX, et al., 2022. Phytoremediation of cadmium-contaminated sediment using Hydrilla verticillata and Elodea canadensis harbor two same keystone rhizobacteria Pedosphaeraceae and Parasegetibacter. Chemosphere, 286:131648.

[69]ZerullaW, BarthT, DresselJ, et al., 2001. 3,4-Dimethylpyrazole phosphate (DMPP) ‒ a new nitrification inhibitor for agriculture and horticulture: an introduction. Biol Fert Soils, 34(2):79-84.

[70]ZhangZF, ZhangWF, 2008. The situation and trend of fertilizer application in China. Phosphate Compd Fert, 23(6):9-12 (in Chinese).

[71]ZhouX, WangSW, MaST, et al., 2020. Effects of commonly used nitrification inhibitors—dicyandiamide (DCD), 3,4-dimethylpyrazole phosphate (DMPP), and nitrapyrin—on soil nitrogen dynamics and nitrifiers in three typical paddy soils. Geoderma, 380:114637

[72]ZhuHH, ChenC, XuC, et al., 2016. Effects of soil acidification and liming on the phytoavailability of cadmium in paddy soils of central subtropical China. Environ Pollut, 219:99-106.

[73]ZhuYX, DuWX, FangXZ, et al., 2020. Knockdown of BTS may provide a new strategy to improve cadmium-phytoremediation efficiency by improving iron status in plants. J Hazard Mater, 384:121473.

[74]ZhuYX, ZhuangY, SunXH, et al., 2023. Interactions between cadmium and nutrients and their implications for safe crop production in Cd-contaminated soils. Crit Rev Environ Sci Technol, 53(24):2071-2091.

[75]ZulfiqarU, AyubA, HussainS, et al., 2022. Cadmium toxicity in plants: recent progress on morpho-physiological effects and remediation strategies. J Soil Sci Plant Nutr, 22(1):212-269.