聚乙烯和聚乳酸微塑料对大豆生长和生理生化及代谢的影响

为揭示生物可降解性不同的微塑料对农作物的毒性效应,选择聚乳酸(polylactic acid可生物降解)和聚乙烯(polyethylene难生物降解)微塑料(microplastics)为供试材料,以大豆为供试植物,深入探究了不同暴露水平(0.1%,1%,W/W)下两种不同的微塑料对大豆(Glycine max)生长、光合作用、抗氧化性、营养品质以及代谢方面的影响.结果表明,聚乙烯微塑料(PEMPs)对大豆根部鲜重有促进作用,而0.1%聚乳酸微塑料(PLAMPs)则抑制根部长度.大豆的叶绿素含量在0.1% PEMPs作用下能够显著提高.PLAMPs则能够导致大豆过氧化氢酶(CAT)活性显著下降,而过氧化氢(H₂O₂)含量在0.1% PEMPs和1% PLAMPs下显著升高.此外,微塑料的暴露能够改变大豆根部中锰、铁以及铜的含量,其中0.1% PEMPs的效应最为显著.大豆叶片中的氨基酸代谢在PEMPs的作用下上调,而0.1% PLAMPs则引起有机酸以及糖类代谢下调.综上,微塑料的植物毒性效应与其生物可降解性及浓度密切相关,低浓度可生物降解微塑料的效应最强.这些发现有望为微塑料的植物毒理研究提供新的方向.

Impact of polyethylene and polylactic acid microplastics on growth,physio-biochemistry and metabolism in soybean (Glycine max)

The influence of bio (polylactic acid) and non-biodegradable (polyethylene) at two different concentrations (0.1%, 1%,W/W) on the growth, photosynthesis, oxidation resistance, nutritional quality, and metabolism of soybean (Glycine max) were deeply studied to reveal the ecotoxicological impact of microplastics with different biodegradability on crops. Results revealed that polyethylene microplastics (PEMPs) tend to increase the fresh weight of Glycine max roots. The treatment of 0.1% Polylactic acid microplastics (PLAMPs) inhibited the root length. Whereas, PEMPs enhanced the chlorophyll content of Glycine max significantly. The catalase (CAT) activity was decreased under PLAMPs, while the hydrogen peroxide (H₂O₂) content was increased by 0.1% PEMPs and 1% PLAMPs exposure. In addition, the Mn, Fe, and Cu content of Glycine max roots also changed, which had the most obvious impact with 0.1% PEMPs. Furthermore, the amino acid metabolisms in Glycine max were up regulated under PEMPs, while organic acid and sugar metabolisms were down regulated under 0.1% PLAMPs. Overall, the phytotoxicity of microplastics is closely related to their biodegradability and concentrations. Biodegradable microplastics at lower doses had the most profound effect on Glycine max. These findings are expected to provide new insights into the effects of microplastics on crop plants in the future.