In conventional agricultural practices, pesticides are applied to protect crops from harmful insect pests; however, pervasive usage in high-yield crop systems poses a significant risk to the viability and sustainability of agroecosystems. Agricultural output may be adversely affected by pesticide deposition in the soil as it affects biochemical interactions between plants and soil. Pesticides cause oxidative stress by blocking physiological and biochemical pathways and disrupting the photosynthetic machinery of plants. When exposed to abiotic challenges, plant growth regulators (PGRs) such as auxin, gibberellins, cytokinin and abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), brassinosteroids (BR), and 24-epibrassinolides (EBL) reduce pesticide toxicity by strengthening antioxidant defence mechanisms and enhancing tolerance to stressful conditions. By modulating a variety of physio-biochemical mechanisms, PGRs reduce pesticide toxicity in intact plants. Furthermore, PGRs eliminate reactive oxygen species (ROS) generation by inducing antioxidant enzyme production. Pesticide residues in plant compartments are reduced as a result of PGR-mediated increase in pesticide degradation. This review provides a detailed account of the potential role of PGRs in pesticide detoxification and growth promotion in plants. This work examines several elements of plant pesticidal reactions and assesses how PGRs support plants in tolerating pesticides. The underlying mechanisms during pesticide stress are also discussed. The need for additional study on PGR applications is also emphasized.

Heavy metal contamination negatively affects plants and animals in water as well as soils. Some microalgae can remove heavy metal contaminants from wastewater. The aim of this study was to screen green microalgae (GM) to identify those that tolerate high concentrations of toxic heavy metals in water as possible candidates for phytoremediation. Analyses of the tolerance, physiological parameters, ultrastructure, and transcriptomes of GM under Cd/Pb treatments were conducted. Compared with the other GM, Chlorella pyrenoidosa showed stronger tolerance to high concentrations of Cd/Pb. The reduced glutathione content and peroxidase activity were higher in C. pyrenoidosa than those in the other GM. Ultrastructural observations showed that, compared with other GM, C. pyrenoidosa had less damage to the cell surface and interior under Cd/Pb toxicity. Transcriptome analyses indicated that the peroxisome and sulfur metabolism pathways were enriched with differentially expressed genes under Cd/Pb treatments, and that CpSAT, CpSBP, CpKAT2, Cp2HPCL, CpACOX, CpACOX2, and CpACOX4, all of which encode antioxidant enzymes, were up-regulated under Cd/Pb treatments. These results show that C. pyrenoidosa has potential applications in the remediation of polluted water, and indicate that antioxidant enzymes contribute to Cd/Pb detoxification. These findings will be useful for producing algal strains for the purpose of bioremediation in water contamination.