Understanding these regulatory networks is crucial for improving crop nutrient use efficiency and stress resilience, key objectives for achieving sustainable agriculture under increasingly challenging environmental constraints (Antony Ceasar et al. , 2023). Abiotic stress tolerance was lost during crop domestication (Palmgren et al. , 2015;Wang et al. , 2020) ; as a result, crop production across the globe is severely affected by various climate-driven constraints such as drought, heat, salinity, and flooding, costing industry over 180Bln p. a. in lost productivity (Razzaq et al. , 2021). Regaining this tolerance is a challenging process that may require a paradigm shift in identifying appropriate breeding targets. Membrane transporters are ideally suited for this purpose. In this Research Topic, we have compiled a series of reviews and research articles focusing on recent advances in nutrient transport and signaling, with emphasis on nitrogen (N), silicon (Si), carbon (C) allocation, and ion homeostasis under stress conditions. These studies span model plants such as Arabidopsis and rice, as well as economically important species including cucumber and the intertidal macroalga Pyropia haitanensis. Nitrate (NO3 -) serves not only as a primary N source but also as a key signaling molecule. In this volume, Mao et al. (2026) elucidate how NO3 -signaling integrates with hormones, calcium-dependent phosphorylation cascades (e. g. , CBL-CIPK, CPK), reactive oxygen species (ROS), and root-derived peptides (e. g. , CEP) to fine-tune root architecture and systemically integrate C-N status. Deeper understanding of this multi-layered network provides actionable targets for improving nitrogen use efficiency (NUE) through genome editing, synthetic chemicals, and engineered nitrogen redistribution (SINAR). Earlier, the rice NO3 -transporter NRT1. 1B has been identified as a dual receptor for nitrate and ABA (Ma et al. , 2025). Competitive binding at adjacent sites triggers distinct pathways, promoting growth under high NO3 -and activating stress responses under low NO3 -or ABA accumulation. The OsNRT1. 1B-OsSPX4-OsNLP4 module therefore functions as a dynamic molecular switch, balancing nutrient acquisition and stress defense and offering precise targets for simultaneously enhancing NUE and stress tolerance. The molecular regulatory network of NUE in rice was systematically reviewed by Guo et al. (2026). As an ammonium (NH4 +) -preferring crop, rice utilizes both NH₄⁺ and NO₃⁻, with uptake mediated by the OsAMT and OsNRT/NPF families, respectively. Key regulators, including transcription factors such as OsWRKY23, OsDREB1C, OsGRF4, and OsNGR5, as well as auxin-related OsDNR1, form a signaling network that coordinates N uptake, assimilation, and allocation. NUE differences between indica and japonica subspecies partly stem from natural variations in genes such as OsNRT1. 1B and OsDNR1. Additionally, pH homeostasis (via OsNRT2. 3b and OSA1) and multi-gene synergies (e. g. , OsAMT1. 2/OsGS1. 2/OsAS1) are crucial for achieving high yield and enhanced NUE. Recent studies have further revealed that high-NH₄⁺ stress induces NH₄⁺ toxicity in plants, with futile NH₄⁺ efflux serving as a key mechanism underlying this toxicity. The magnitude of NH₄⁺ efflux has been shown to be significantly negatively correlated with both high-NH₄⁺ tolerance and NUE in rice (Di et al. , 2025). Pharmacological or genetic suppression of this efflux enhances NH₄⁺ uptake and alleviates toxicity, pointing to a tripartite strategy: enhance uptake, optimize assimilation, and suppress efflux (Wu et al. , 2025). The role of PRPs in Si biomineralization was investigated by Sun et al. (2026) using cucumber as a target species. Among seven CsPRP genes, tandem duplicates CsPRP1 and CsPRP3 share high evolutionary and expression similarity. Both exhibit strong Si-binding activity under distinct pH conditions and localize polarly in the cell wall. Their expression correlates with tissue Si accumulation, mainly in mature leaves and roots at the seedling stage, expanding to leaves, roots, petals, and stamens at maturity. These findings clarify the mechanistic role of PRPs in Si deposition and support strategies for enhancing crop stress tolerance through Si application. Collectively, the articles highlight a recurring theme: nutrient movement and stress adaptation are governed by complex, interconnected systems. Transporters are not merely conduits for nutrient movement, but dynamic regulatory components integrated into larger networks involving signal transduction, protein-protein interactions, and metabolic feedback loops. Future research and breeding efforts should move beyond manipulating single genes toward system-level approaches. This may include: • Elucidating signal crosstalk to deepen our understanding of how nutrient signals (e. g. , NO3 -, Si) interact with hormones, ROS, and energy (carbon) status to coordinate whole-plant responses. • Leverage insights from protein interactomes (e. g. , PhNKA2 interactors) and regulatory factors (e. g. , UBC34 for AVP1) to enhance the stability, activity, and specificity of key transporters and enzymes. • Utilize tissue-specific or inducible promoters, gene-editing tools (e. g. , CRISPR-Cas9), and synthetic biology to control gene expression and protein function spatiotemporally, minimizing pleiotropic effects. • Integrating multiple traits by stack genes that improve nutrient uptake (N, Si), efficient C allocation, and robust ion homeostasis (Na⁺/K⁺) to develop crops that simultaneously achieve high yield, enhanced nutrient use efficiency, and resilience to key abiotic stresses. Abiotic stress tolerance has been present in wild crop relatives but lost during domestication (Palmgren and Shabala, 2024). By integrating molecular insights gained from evolutionary diverse plant systems algae, we can accelerate the design of next-generation crops capable of addressing the dual challenges of global food security and environmental sustainability.
Di et al. (Tue,) studied this question.