College of Grassland Agriculture, Northwest A&F University, Yangling, 712100, China.
College of Horticulture, Northwest A&F University, Yangling, 712100, China.
Plant Physiol Biochem. 2024 Oct;215:109002. doi: 10.1016/j.plaphy.2024.109002. Epub 2024 Jul 31.
Cadmium (Cd) toxicity poses a significant threat to soil health and sustainable food production. Its bioaccumulation in plant tissues induces phytotoxicity by affecting physiological and biochemical attributes, leading to a reduction in plant biomass and production. Recently, nanotechnology has emerged as a promising approach for addressing heavy metal toxicity in an eco-friendly manner to enhance crop production. However, the comparative role of foliar applied calcium oxide nanoparticles (CaO-NPs) and bulk calcium fertilizer under Cd stress in alfalfa remains unexplored. Herein, we studied the ameliorative role of CaO-NPs and bulk calcium (50 and 100 mg L) to alleviate Cd stress (30 mg kg) in alfalfa seedlings. Plants exposed to Cd exhibited significant decreases in morpho-physiological traits, gas exchange attributes, and pigment contents as well as increase in Cd bioaccumulation in plant tissues. Notably, exogenous application of CaO-NPs ameliorates the toxic impact of Cd by enhancing plant biomass (45%), fluorescence efficiency and gaseous exchange attributes. The maximum dose of CaO-NPs induced Cd-tolerance response accompanied by a significant increase in antioxidative enzyme activities, such as superoxide dismutase (SOD; 29%), peroxidase (POD; 41%), catalase (CAT; 36%) and ascorbate peroxidase (APX; 49%), which play positive roles in ROS scavenging. TEM examination further revealed the protective role of these NPs in averting Cd-induced damage to leaf ultrastructure and mesophyll cells. Furthermore, CaO-NPs had a substantial influence on both Cd and Ca accumulation in plant tissues, while qRT‒PCR analysis demonstrated higher expression of antioxidant defense genes viz. Cu/ZnSOD (0.38 fold change (FC)), MtPOD (0.51 FC), MtCAT (0.61 FC) and MtAPX (0.79 FC) under CaO-NPs application, over Cd control. Overall, our findings suggested that exogenous CaO-NPs could be effective in alleviating the adverse effects of Cd on alfalfa seedlings to ensure food safety and support sustainable agriculture.
镉（Cd）毒性对土壤健康和可持续粮食生产构成重大威胁。它在植物组织中的生物积累通过影响生理生化特性诱导植物毒性，导致植物生物量和产量减少。最近，纳米技术作为一种有前途的方法，以生态友好的方式解决重金属毒性，以提高作物产量。然而，叶面喷施氧化钙纳米颗粒（CaO-NPs）和 bulk 钙肥在紫花苜蓿 Cd 胁迫下的比较作用仍未得到探索。在此，我们研究了 CaO-NPs 和 bulk 钙（50 和 100mg/L）在缓解紫花苜蓿幼苗 Cd 胁迫（30mg/kg）中的缓解作用。暴露于 Cd 的植物表现出形态生理特性、气体交换特性和色素含量的显著降低，以及植物组织中 Cd 生物积累的增加。值得注意的是，外源应用 CaO-NPs 通过增强植物生物量（45%）、荧光效率和气体交换特性来缓解 Cd 的毒性影响。最大剂量的 CaO-NPs 诱导 Cd 耐受性反应，同时显著增加抗氧化酶活性，如超氧化物歧化酶（SOD；29%）、过氧化物酶（POD；41%）、过氧化氢酶（CAT；36%）和抗坏血酸过氧化物酶（APX；49%），这些酶在清除 ROS 方面发挥积极作用。TEM 检查进一步揭示了这些 NPs 在避免 Cd 诱导的叶片超微结构和叶肉细胞损伤方面的保护作用。此外，CaO-NPs 对植物组织中 Cd 和 Ca 的积累有很大影响，而 qRT-PCR 分析表明，抗氧化防御基因的表达更高，如 Cu/ZnSOD（0.38 倍变化（FC））、MtPOD（0.51 FC）、MtCAT（0.61 FC）和 MtAPX（0.79 FC）在 CaO-NPs 应用下，超过 Cd 对照。总的来说，我们的研究结果表明，外源 CaO-NPs 可以有效地缓解 Cd 对紫花苜蓿幼苗的不利影响，以确保食品安全和支持可持续农业。
