AP2/ERF (APETALA2/ethylene-responsive factor) is one of the largest plant transcription factor families, characterized by 1-2 AP2/ERF domains (≈60–70 amino acids) that regulate plant development and biotic/abiotic stress responses. This study presents the first genome-wide identification and characterization of the AP2/ERF family in the selenium (Se) hyperaccumulator Cardamine hupingshanensis via bioinformatics. A total of 230 AP2/ERF genes were identified, which were non-randomly distributed across 16 chromosomes. Their encoded proteins varied in length (126–623 aa), molecular mass (13.927–68.112 kDa), and isoelectric point (4.48–10.31). Phylogenetic analysis classified these genes into five conserved subfamilies (AP2, DREB, ERF, RAV, Soloist), consistent with other plant species. Intron distribution differed among subfamilies (42.17% of genes contained introns), and motif 1 was universally conserved. Promoter cis-element analysis revealed enrichment of hormone-, stress-, and growth-related elements, highlighting potential roles in abiotic stress responses (notably, light and abscisic acid signaling). Expression profiling under Se stress (100 μg Se/L and 80,000 μg Se/L) demonstrated tissue-specific, dose-dependent, and temporal dynamic patterns. This inaugural genome-wide investigation of C. hupingshanensis AP2/ERFs provides foundational datasets for deciphering regulatory networks governing growth and Se stress response in this Se hyperaccumulator plant.

The thioredoxin system is crucial for maintaining redox balance and stress responses in plants, but its role in selenium hyperaccumulators remains poorly understood. To our knowledge, this study is the first to perform a genome-wide identification of the thioredoxin system in Se hyperaccumulator Cardamine hupingshanensis. We identified 74 ChTRX genes and 12 ChTR genes, among which ChTRX genes accounted for approximately 86.05% of the total identified thioredoxin system genes. Phylogenetic and structural analyses classified the ChTRXs into two types, typical (with the WCGPC active site) and atypical (with the XCXXC active site), with typical ChTRXs comprising about 48.65% and atypical ChTRXs about 51.35% of the total ChTRXs. Subcellular localization analysis revealed a diverse distribution, such as chloroplast, mitochondrion and cytoplasm. The chloroplast-localized ChTRXs are the most abundant, accounting for approximately 60% of all ChTRXs. Under Se stress, the expression of ChTRX genes exhibited significant tissue-specific differences: approximately 52.5% of ChTRX genes showed responsive expression in the roots, while only 31.25% responded in the leaves, suggesting that root-specific genes may play an important role in mitigating Se-induced oxidative damage. Through expression data and molecular docking analysis, we discovered that ChACHT4-1 can interact with the disulfide bonds of key Se metabolism related enzymes ChAPK and ChAPR, suggesting its potential reductive activity. Furthermore, we predicted stress-responsive ChTRXs regulated by multiple ChNTRs in TRX–TR regulatory pathway. Overall, our research indicates that the thioredoxin system influences Se metabolism in C. hupingshanensis through redox regulation, providing insights into the Se tolerance mechanisms of hyperaccumulating plants and offering perspectives for optimizing Se biofortification strategies in crops.

The glutaredoxin (GRX) system is one of the important antioxidant systems in plants, involving two key enzymes: GRX and glutathione reductase (GR). The bas

Cardamine hupingshanensis (C. hupingshanensis) is an important dietary source of selenium for humans due to its remarkable capacity for selenium hyperaccumulation. As core components of the SCF (SKP1–Cullin–F-box) ubiquitin ligase complex, F-box proteins play vital roles in plant responses to environmental stress, such as salt and drought. However, information regarding the F-box gene family in C. hupingshanensis and its potential functions in regulating responses to abiotic stress remains limited. In this study, members of the F-box gene family in C. hupingshanensis were identified through sequence alignment. Comprehensive bioinformatic analyses, including analyses of physicochemical properties, phylogenetic relationships, subcellular localization, conserved motifs and domains, gene structure, chromosomal distribution, promoter cis-elements, and gene duplication events, were performed using TBtools and associated online resources. In particular, a total of 548 F-box genes were identified and classified into nine distinct groups based on phylogenetic analysis. Protein sequence analysis predicted 15 conserved motifs and 18 distinct domains across the identified F-box proteins. Promoter analysis suggested the presence of 32 different cis-elements that may be potentially associated with growth, development, hormone signaling, and abiotic stress responses. Furthermore, 283 collinear gene pairs were detected within the C. hupingshanensis genome, providing insights into the possible expansion of this gene family. Quantitative real-time PCR was employed to examine the tissue-specific expression levels of F-box genes in various organs, as well as their expression profiles in response to exogenous selenium, salt, osmotic stress, and abscisic acid treatment. The results indicated that 11 ChFBX genes responded to exogenous selenium, salt, osmotic stress, or abscisic acid. Notably, transgenic plants overexpressing ChFBX171 displayed heightened sensitivity to salt stress during seed germination. In conclusion, this study provides a comprehensive identification and characterization of 548 F-box genes in C. hupingshanensis and offers valuable insights into the potential role of ChFBX genes, particularly ChFBX171, in mediating responses to abiotic stress.

Multi-walled carbon nanotubes (MWCNTs) can modulate plant growth and development, but the signaling mechanisms underlying their effects on organogenesis remain unclear. Here, we found that MWCNTs promote adventitious root (AR) formation and that RBOH-dependent hydrogen peroxide (H₂O₂) production plays a key role in this process in cucumber (Cucumis sativus L.) and Arabidopsis thaliana. MWCNTs treatment promoted AR formation in cucumber hypocotyls. Concomitantly, endogenous H₂O₂ levels increased rapidly, along with enhanced CsRBOHD expression and NADPH oxidase activity, suggesting activation of an RBOH-dependent H₂O₂ response. Consistent with this, scavenging H₂O₂ or inhibiting NADPH oxidase markedly reduced MWCNTs-induced rooting, whereas exogenous H₂O₂ partially restored AR formation under NADPH oxidase inhibition. Genetic evidence further supported this relationship, as Atrbohd and Atrbohf mutants showed reduced responses to MWCNTs but remained responsive to exogenous H₂O₂, suggesting that RBOH-mediated H₂O₂ generation is a critical step in MWCNTs-induced adventitious rooting. In parallel, MWCNTs and H₂O₂ treatments enhanced the expression of genes associated with adventitious root development. Together, these findings support a model in which MWCNTs promote adventitious rooting through RBOH-dependent H₂O₂ signaling, providing new insight into nanomaterial-mediated regulation of plant development.