铀胁迫下根施褪黑素和苏云金芽孢杆菌对上海青生长和铀吸收的影响

Effect of Melatonin and Bacillus thuringiensis on Growth and Uranium Uptake of Brassica chinensis L Under Uranium Stress

[目的]揭示褪黑素和苏云金芽孢杆菌对上海青缓解铀胁迫的作用机制,为褪黑素-抗性菌-植物联合修复铀污染土壤的应用提供理论依据。[方法]通过室内盆栽试验,以添加铀(10 mg/kg)污染红壤为供试土壤,研究褪黑素(100μmol/L)、铀抗性菌苏云金芽孢杆菌以及联合施用下对土壤pH和养分、上海青生长生理特性以及在土壤-上海青系统中铀含量和转运的影响。[结果](1)褪黑素和苏云金芽孢杆菌显著促进了上海青的生长,提高了上海青的株高(1.8%~11.8%)、生物量(0.8%~34.4%)、叶绿素含量(12.1%~50.2%)和养分含量(7.1%~39.5%);(2)褪黑素和苏云金芽孢杆菌减弱了铀胁迫对上海青造成的氧化损伤,增强了抗氧化损伤防御能力,进而促进上海青的生长;(3)褪黑素和苏云金芽孢杆菌增加了根的富集系数(9.26%),降低了铀从根向叶的转运,进而降低了食用上海青的风险;(4)褪黑素和苏云金芽孢杆菌在减轻上海青中铀含量和促进上海青生长方面有协同作用,联合施用效果更好。[结论]褪黑素和抗性菌通过显著增强土壤酶活性和上海青抗氧化防御,增强上海青对养分的吸收、减弱氧化损伤,维持细胞稳态,来减弱上海青对铀的吸收与转运,促进植物生长。

[Objective]This study aims at revealing the mechanism of melatonin and Bacillus thuringiensis on alleviating uranium stress in Brassica chinensis L,and providing a theoretical basis for the combined application of melatonin-resistant bacteria-plant to ameliorate uranium-contaminated soil.[Methods]Through indoor pot experiment of adding uranium(10 mg/kg),the effects of melatonin(100μmol/L),the uranium resistant bacteria B.thuringiensis on the growth and physiological characteristics of B.chinensis.and the uranium contents and transport in soil and B.chinensis system were studied.[Results](1)Melatonin and B.thuringiensis significantly promoted the growth of B.chinensis,increased the plant height(1.8%~11.8%),biomass(0.8%~34.4%),chlorophyll content(12.1%~50.2%)and nutrient content(7.1%~39.5%).(2)Melatonin and B.thuringiensis attenuated the oxidative damage caused by uranium stress to B.chinensis,enhanced the defense of the oxidative damage system,and promoted the growth of B.chinensis.(3)Melatonin and B.thuringiensis significantly reduced the uranium enrichment coefficient(24.4%)and transport coefficient(33.3%),but increased the enrichment coefficient of roots(9.26%),reduced the risk of eating B.chinensis.(4)Melatonin and B.thuringiensis had a synergistic effect on reducing the uranium content and promoting the growth of B.chinensis,and the combined application effect was better.[Conclusion]Melatonin and resistant bacteria can significantly enhance the soil enzyme activity and antioxidant defense of B.chinensis to boost the absorption of nutrients and weaken oxidative damage,to maintain cell homeostasis,to weaken the absorption and transport of B.chinensis,and to promote plant growth.