Transcription factors play a key role in plant growth and development. As the largest family of plant-specific transcription factors, the NAC family plays a central role in coordinating plant growth and development and environmental adaptation through its unique molecular design paradigm of “fixed N-terminal structural domain + variable C-terminal regulatory domain”. This review systematically analyses the multidimensional regulatory mechanisms of NAC transcription factors in developmental processes such as cell wall remodelling, root system architecture, leaf senescence and fruit ripening, and reveals their molecular basis for responding to biotic/abiotic stresses through strategies such as hormone signalling integration (ABA, SA, JA, etc.), antioxidant defence activation and metabolic reprogramming. The study found that NAC proteins precisely control plant growth through multiple regulatory mechanisms and have evolved to form both conservative and diverse functional modules, which are of great value for crop improvement. However, research still faces three major challenges: the NAC regulatory network in different crops is still unclear, the coordinated response to multiple stresses has not been solved, and the ecological risks of gene editing have not been assessed. To this end, this paper proposes to build an ‘NAC regulatory map database’ and use synthetic biology and artificial intelligence technology to design smarter, stress-tolerant and high-yielding crops, overcoming the limitations of traditional research.

Background/Objectives: The GARP transcription factor superfamily is crucial for plant growth, development, and stress responses. This study systematically identified and analyzed the GARP family genes in Populus deltoides to explore their roles in plant development and abiotic stress responses. Methods: A total of 58 PdGARP genes were identified using bioinformatics tools. Their physicochemical properties, genomic locations, conserved motifs, gene structures, and phylogenetic relationships were analyzed. Expression patterns under phosphorus and nitrogen deficiency, as well as tissue-specific expression, were investigated using RT-qPCR. Transgenic RNAi lines were generated to validate the function of GLK genes in chlorophyll biosynthesis. Results: The 58 PdGARP genes were classified into five subfamilies based on their evolutionary relationships and protein sequence similarity. Segmental duplication was found to be the primary driver of the PdGARP family’s expansion. Cis-regulatory elements (CREs) related to light, hormones, and abiotic stresses were identified in the promoters of PdGARP genes. Differential expression patterns were observed for NIGT1/HRS1/HHO and PHR/PHL subfamily members under phosphorus and nitrogen deficiency, indicating their involvement in stress responses. KAN subfamily members exhibited tissue-specific expression, particularly in leaves. Structural analysis of the GLK subfamily revealed conserved α-helices, extended chains, and irregular coils. Transgenic RNAi lines targeting GLK genes showed significant reductions in chlorophyll and carotenoid content. Conclusions: This study provides a comprehensive analysis of the GARP transcription factor superfamily in P. deltoides, highlighting their potential roles in nutrient signaling and stress response pathways. The findings lay the foundation for further functional studies of PdGARP genes and their application in stress-resistant breeding of poplar.

Heavy metal pollution, particularly cadmium (Cd), is a significant environmental and health concern due to its high mobility and bioaccumulation potential. Our study identifies a novel Cd-responsive chelation protein gene, SpPDF, from the hyperaccumulator plant Sedum plumbizincicola, which enhances Cd tolerance through chelation. The SpPDF, belonging to the Knot1 superfamily and lacking a signal peptide, is primarily expressed in roots and is significantly induced by Cd treatment. Subcellular localization studies revealed a cytoplasmic distribution of the SpPDF protein. Heterologous expression in yeast demonstrated that SpPDF improves Cd tolerance and in vitro Cd-binding experiments confirmed SpPDF's chelation activity. Overexpression of SpPDF in plants significantly increased Cd accumulation in roots and decreased it in shoots, attributed to enhanced root chelation capacity and reduced translocation to above-ground parts. This study provides a new molecular approach for improving plant remediation of Cd pollution, challenging the view that defensins are exclusively secreted proteins. Our findings offer valuable insights for the molecular breeding of plants for the phytoremediation of Cd-contaminated soil.

Cadmium (Cd) pollution has caused severe environmental hazards and human health risks. Phytoremediation, a green and sustainable approach, has emerged as a promising solution for Cd-contaminated soil remediation. Sedum plumbizincicola, a typical Cd hyperaccumulator, can efficiently uptake Cd from soil and translocate it to above-ground tissues, making it an ideal model for studying Cd tolerance mechanisms. Our preliminary studies demonstrated that the Rubber elongation factor (SpREFl) enhances Cd tolerance in S. plumbizincicola, and yeast one-hybrid screening identified SpNAC089 (NCBI accession number: PV553670.1) as a potential upstream transcription factor of SpREFl. In this study, we systematically investigated the regulatory mechanism of the SpNAC089 transcription factor on SpREFl. Subcellular localization assays showed that SpNAC089 is exclusively localized in the cell nucleus, and yeast transcriptional activation experiments confirmed its intrinsic transcriptional autoactivation activity. Transgenic S. alfredii overexpressing SpNAC089 exhibited significantly enhanced cadmium tolerance—with milder leaf yellowing and growth inhibition under Cd stress—and reduced Cd accumulation in roots, stems, and leaves compared to wild-type (WT) plants. Further mechanistic analyses revealed that SpNAC089 directly binds to the 1901–1950 bp region of the SpREFl promoter, which contains cis-acting elements (MBS and TCA motifs). This binding activates SpREFl transcription, thereby upregulating the activities of antioxidant enzymes (superoxide dismutase, SOD; peroxidase, POD) and reducing malondialdehyde (MDA) content under Cd stress, ultimately mitigating oxidative damage. These findings uncover a novel transcriptional regulatory pathway (SpNAC089-SpREFl) underlying Cd tolerance in S. plumbizincicola and highlight SpNAC089 as a candidate gene for optimizing phytoremediation strategies of Cd-polluted soils.