College of Resources and Environment, Qingdao Agricultural University, Qingdao, China.
College of Resources and Environment, Qingdao Agricultural University, Qingdao, China.
Chemosphere. 2023 Nov;341:140001. doi: 10.1016/j.chemosphere.2023.140001. Epub 2023 Aug 31.
The use of rapeseed (Brassica napus) as a hyperaccumulator plant has shown great promise for the remediation of cadmium (Cd) contaminated soils. Nanosized materials (NPs) have been shown to mitigate heavy metal toxicity in plants, but it is unknown how l-aspartate nano-calcium (NPs-Ca) affects Cd uptake, transport, and tolerance in rapeseed. A soil pot experiment was conducted with two treatments: a control treatment (CK) with 2.16 g CaCl and NPs-Ca treatment with 6.00 g NPs-Ca, to evaluate the effects and mechanisms of NPs-Ca on Cd tolerance in rapeseed. Compared to CaCl, NPs-Ca promoted Cd transportation from roots to shoots by up-regulating the expression of Cd transport genes (ABCC12, HMA8, NRAM6, ZIP6, CAX4, PCR2, and HIP6). Therefore, NPs-Ca increased Cd accumulation in rapeseed shoots by 39.4%. Interestingly, NPs-Ca also enhanced Cd tolerance in the shoots, resulting in lower hydrogen peroxide (HO) accumulation and proline content, as well as higher antioxidant enzyme activities (POD, CAT). Moreover, NPs-Ca reduced the activity of pectin-degrading enzymes (polygalacturonase: PG, β-galactosidase: β-GAL), promoted the activity of pectin methyl esterase (PME), and changed transcription levels of related genes (PME, PMEI, PG, PGIP, and β-GAL). NPs-Ca treatment also significantly increased the Cd content in cell walls by 59.8%, that is, more Cd was immobilized in cell walls, and less Cd entered organelles in shoots of NPs-Ca treatment due to increased pectin content and degree of pectin demethylation. Overall, NPs-Ca increased Cd accumulation in rapeseed shoots by promoting Cd transport from roots to shoots. And meantime, NPs-Ca enhanced Cd tolerance of shoots by inhibiting pectin degradation, promoting pectin demethylation and increasing Cd fixation in pectin. These findings suggest that NPs-Ca can improve the potential of rapeseed as a hyperaccumulator for the remediation of Cd-contaminated soil and the protection of the environment. Furthermore, the study provides a theoretical basis for the application of NPs-Ca in the phytoremediation of Cd-contaminated soils with hyperaccumulating plants.
利用油菜（甘蓝型油菜）作为超积累植物，对于修复镉（Cd）污染土壤具有很大的前景。纳米材料（NPs）已被证明可以减轻植物的重金属毒性，但尚不清楚 L-天冬氨酸纳米钙（NPs-Ca）如何影响油菜对 Cd 的吸收、运输和耐受性。进行了一项土壤盆栽实验，有两个处理：对照处理（CK）用 2.16 g CaCl 和 NPs-Ca 处理用 6.00 g NPs-Ca，以评估 NPs-Ca 对油菜 Cd 耐受性的影响和机制。与 CaCl 相比，NPs-Ca 通过上调 Cd 转运基因（ABCC12、HMA8、NRAM6、ZIP6、CAX4、PCR2 和 HIP6）促进 Cd 从根部向地上部的运输，从而增加油菜地上部的 Cd 积累。因此，NPs-Ca 使油菜地上部的 Cd 积累增加了 39.4%。有趣的是，NPs-Ca 还增强了油菜地上部的 Cd 耐受性，导致 H2O2（HO）积累和脯氨酸含量降低，抗氧化酶活性（POD、CAT）升高。此外，NPs-Ca 降低了果胶降解酶（多聚半乳糖醛酸酶：PG、β-半乳糖苷酶：β-GAL）的活性，促进了果胶甲酯酶（PME）的活性，并改变了相关基因（PME、PMEI、PG、PGIP 和 β-GAL）的转录水平。NPs-Ca 处理还使细胞壁中的 Cd 含量增加了 59.8%，也就是说，由于果胶含量增加和果胶脱甲基化程度增加，更多的 Cd 被固定在细胞壁中，而较少的 Cd 进入油菜地上部的细胞器。总之，NPs-Ca 通过促进 Cd 从根部向地上部的运输，增加了油菜地上部的 Cd 积累。同时，NPs-Ca 通过抑制果胶降解、促进果胶脱甲基化和增加果胶中 Cd 的固定，增强了油菜地上部的 Cd 耐受性。这些发现表明，NPs-Ca 可以提高油菜作为修复 Cd 污染土壤和保护环境的超积累植物的潜力。此外，该研究为 NPs-Ca 在利用超积累植物修复 Cd 污染土壤中的应用提供了理论依据。
