Heavy metal toxicity generally refers to the negative impact on the environment, humans, and other living organisms caused by exposure to heavy metals (HMs). Heavy metal poisoning is the accumulation of HMs in the soft tissues of organisms in a toxic amount. HMs bind to certain cells and prevent organs from functioning. Symptoms of HM poisoning can be life-threatening and not only cause irreversible damage to humans and other organisms; but also significantly reduce agricultural yield. Symptoms and physical examination findings associated with HM poisoning vary depending on the metal accumulated. Many HMs, such as zinc, copper, chromium, iron, and manganese, are present at extremely low levels but are essential for the functioning of plants. However, if these metals accumulate in the plants in sufficient concentrations to cause poisoning, serious damage can occur. Rice is consumed around the world as a staple food and incidents of HM pollution often occur in rice-growing areas. In many rice-producing countries, cadmium (Cd), arsenic (As), and lead (Pb) have been recognized as commonly widespread HMs contaminating rice fields worldwide. In addition to mining and irrigation activities, the use of fertilizers and pesticides has also contributed significantly to HM contamination of rice-growing soils around the world. A number of QTLs associated with HM stress signals from various intermediary molecules have been reported to activate various transcription factors (TFs). Some antioxidant enzymes have been studied which contribute to the scavenging of reactive oxygen species, ultimately leading to stress tolerance in rice. Genome engineering and advanced editing techniques have been successfully applied to rice to improve metal tolerance and reduce HM accumulation in grains. In this review article, recent developments and progress in the molecular science for the induction of HM stress tolerance, including reduced metal uptake, compartmentalized transportation, gene-regulated signaling, and reduced accumulation or diversion of HM particles to plant parts other than grains, are discussed in detail, with particular emphasis on rice.

The plant epidermis, adorned with trichomes and root hairs, represents a critical interface where developmental programming and environmental responses converge. Although the genetic basis of epidermal patterning has been extensively characterized in model systems, how these pathways are modulated under abiotic stress remains incompletely understood. This review integrates recent advances in epidermal development and stress biology, focusing on MYB–bHLH–WD40 (MBW) complexes, GIS-family C2H2 zinc-finger proteins, and ROOT HAIR DEFECTIVE SIX-LIKE (RSL) transcription factors. These regulators participate in interconnected, organ-specific networks that coordinate trichome and root-hair development. Their activities are shaped by gibberellin–brassinosteroid interactions, ethylene–auxin coordination, jasmonate and abscisic acid signaling, and cytokinin- and nutrient-responsive pathways. We further discuss how reactive oxygen species and calcium oscillations translate transcriptional regulation into polarized cell growth. The resulting epidermal plasticity reflects trade-offs among growth, defense, resource acquisition, and conservation. By integrating single-cell transcriptomics, nutrient sensing, and evolutionary perspectives, this review provides a framework for understanding environmentally responsive epidermal development and identifies opportunities for improving crop resilience. The resulting framework identifies testable opportunities for crop improvement, while emphasizing that native network equivalence, pleiotropic effects, and field-level stress benefits remain to be established in crop species.

This narrative review synthesizes current knowledge on MADS-Box 27 (OsMADS27), a member of the AGL17 clade in rice that has emerged as a regulatory node linking nitrate signaling, root development, and abiotic stress tolerance. Because most functional and mechanistic studies on OsMADS27 to date have been conducted in rice, this review is centered on Oryza sativa, with cross-species comparisons used for evolutionary and comparative context. Specifically, we summarize the gene and protein structure, phylogenetic position, expression profile, upstream and downstream regulation, and emerging functional significance of OsMADS27. OsMADS27 is a typical MIKC-type MADS-box protein with root-preferential expression, and its activity is strongly influenced by nitrate availability and miR444-mediated regulation. Evidence from functional genomics, transcriptomics, ChIP-based studies, and transgenic analyses suggests that OsMADS27 contributes to the regulation of root architecture, nitrate uptake, hormonal crosstalk, and stress-responsive pathways. Notably, OsMADS27 enhances salt tolerance through nitrate-dependent activation of downstream targets such as OsHKT1;1 and OsSPL7, contributing to ion homeostasis and salinity tolerance. Recent findings also suggest roles in grain size regulation and yield improvement, expanding its significance beyond root biology. This review compares OsMADS27 with AGL17-clade genes and highlights its value for crop improvement aimed at salinity tolerance and nitrogen use efficiency. However, important research gaps remain, particularly the limited field-level validation, the absence of integrated multi-omics analyses, and the lack of functional studies of OsMADS27 orthologs in non-rice crops. Overall, OsMADS27 represents promising rice-centered target for future biotechnology applications, while its translational relevance to other cereals remains to be established through orthology analysis and field-level evaluation.