Elevated atmospheric carbon dioxide (ECO2) is a key climatic factor influencing the resilience of plant–microbial symbiotic systems against heavy metal contamination. Robinia pseudoacacia–rhizobia symbiosis shows great potential for cadmium (Cd) remediation. However, the mechanism by which ECO2 regulates Cd phytostabilization in symbiosis remains unclear. This study conducted a 90-day experiment in growth chambers to investigate the effects of ECO2 on the growth, Cd accumulation and chemical forms, as well as nutrient uptake and antioxidant system in Robinia pseudoacacia–rhizobia symbiosis. Results indicated that ECO2 significantly increased plant biomass and photosynthetic efficiency while significantly raising Cd content in roots (34.5%, p < 0.001) and decreasing it in shoots (31.4%, p < 0.001). This resulted in a significant reduction in Cd translocation factor (TF). Meanwhile, ECO2 markedly increased Cd accumulation in roots (81.2%, p < 0.001) and reduced the bioavailability of Cd in the symbiosis. Moreover, ECO2 promoted the content of nutrients and stimulated the antioxidant system. The random forest model indicated that root weight, Cd and Mn contents are the core factors for ECO2-driven Cd phytostabilization. This study demonstrates that ECO2 enhanced Cd phytostabilization by optimizing the resistance of symbiosis to Cd, offering a novel perspective for predicting plant–microbe joint restoration of heavy metal pollution under global climate change scenarios.
Xun Wang, Ruo-Shi Wang, Shao-Xiong Lin et al.· Toxics· 0 citations
Heavy metal contamination is a major environmental constraint that negatively affects plant growth, metabolism, and agricultural productivity. Excess metals such as cadmium, lead, and copper disturb cellular functions mainly by inducing oxidative stress, disrupting nutrient balance, and causing toxicity at multiple levels of organization. To cope with these stresses, plants activate complex defense systems, among which melatonin (MT) (N-acetyl-5-methoxytryptamine) has recently emerged as a key regulatory molecule. This review highlights MT's central role in coordinating plant responses to heavy metal stress. MT strengthens redox homeostasis by enhancing both enzymatic and non-enzymatic antioxidant systems, thereby reducing reactive oxygen species (ROS) accumulation and limiting oxidative damage to cellular components. In addition to its antioxidant function, MT regulates metal uptake, transport, and sequestration by modulating transporter families such as NRAMP, ZIP, and HMA, while also promoting detoxification through phytochelatin (PC) and metallothionein (MT) pathways. MT also plays an important role in hormonal crosstalk, interacting with abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) signaling pathways to fine-tune stress perception and downstream defense responses. Furthermore, recent multi-omics studies have shown that MT induces broad transcriptional, proteomic, and metabolomic reprogramming, leading to coordinated adjustments in gene expression, protein activity, and metabolic pathways under heavy metal stress. Overall, MT functions as a central signaling hub that integrates redox regulation, hormonal signaling, and multi-omics networks to enhance plant tolerance to heavy metal stress. These insights deepen understanding of plant stress biology and offer promising strategies to improve crop resilience and phytoremediation efficiency in contaminated environments.
Si-Xi Zhu, Yu-Tian Lv, Shao-Xiong Lin et al.· Plant physiology and biochem...· 0 citations
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