It is shown that Oryza sativa RGF1-1 (OsRGF1-1) functions as a rice homologue of Arabidopsis RGF1 (AtRGF1), providing the first functional evidence that the RGF1–receptor–ROS signalling module is evolutionarily conserved in the regulation of root meristem development.
Abstract
The root meristem is essential for stem cell maintenance and root development in plants. In Arabidopsis, Root meristem Growth Factor (RGF) peptides and their receptors regulate root meristem size through reactive oxygen species (ROS)-dependent signalling. RGF1-mediated ROS redistribution post-translationally stabilises the root meristem master regulator PLETHORA2 (PLT2). Although genomic studies suggest that RGF–receptor modules are evolutionarily conserved across land plants, their functional characterisation has remained largely limited to Arabidopsis. Here, we show that Oryza sativa RGF1-1 (OsRGF1-1) functions as a rice homologue of Arabidopsis RGF1 (AtRGF1). CRISPR/Cas9-generated Osrgf1-1 mutants exhibited shorter seminal roots, reduced root meristem size, and decreased superoxide (O₂•⁻) accumulation. EdU staining further confirmed that cell proliferation activity was reduced in the Osrgf1-1 mutants. The Osrgf1-1 mutants were sensitive to low concentrations of chemically synthesised mature OsRGF1-1 peptide. This low dose of OsRGF1-1 peptide restored seminal root growth and O₂•⁻ accumulation in the Osrgf1-1 mutants but had no detectable effect on the wild type. Functional analyses using Arabidopsis rgfr receptor mutants further demonstrated that OsRGF1-1 is perceived through conserved RGF receptor machinery. Together, our findings provide the first functional evidence that the RGF1–receptor–ROS signalling module is evolutionarily conserved between dicots and monocots in the regulation of root meristem development.
Wheat (Triticum aestivum), a key global crop, faces rising drought stress that limits root growth and water uptake. Root meristem growth factors (RGFs) are small peptides that regulate root stem cell maintenance, meristem activity, and lateral root formation in model plants, yet the RGF gene family remains unexplored in wheat. Here, we performed a comprehensive genome-wide analysis of the TaRGF gene family, identifying 15 genes distributed across the A, B, and D subgenomes and classified into five homeologous groups (TaRGF1–TaRGF5), predominantly located on chromosomes 2 and 6. All TaRGFs contained a characteristic RGF motif, with dibasic cleavage sites and Asp–Tyr motifs indicating conserved maturation mechanisms. Based on the phylogenetic analysis, the TaRGF5 homeologs showed the highest similarity to Arabidopsis thaliana RGF5. Tested RNA-seq data revealed predominantly root-enriched expression for all TaRGF genes, with TaRGF5 exhibiting the most root-preferential and downregulation under drought stress. Quantitative real-time PCR (qRT-PCR) confirmed that drought stress suppressed the expression of TaRGF5A, TaRGF5B, and TaRGF5D in roots of wheat cultivar Sids-13 across all time points, unlike the higher accumulation seen in controls. Promoter analysis predicted a unique BES1 transcription factor binding site exclusively in TaRGF5B, linking brassinosteroid signaling to peptide-mediated root regulation. Structural modeling and molecular docking predicted an interaction between wheat TaRGF5 homeologs and root growth factor-insensitive receptor kinase (TaRGI3), characterized by conserved sulfotyrosine-mediated binding and favorable interaction energetics. Based on this characterization of the wheat RGF gene family, particularly the potential role of TaRGF5 in root development and drought-adaptation signaling, we propose targeting this gene for functional analysis to improve wheat resilience under water-limited conditions.
H. Khalil, Haidar A. Alsahoud, Abdulrahman Darwish Mostafa et al.· International Journal of Mol...· 0 citations
Elucidating the molecular mechanisms underlying ammonium (NH4+)-mediated root system development is critical for alleviating NH4+ toxicity in plants. The Arabidopsis thaliana [Ca2+]cyt-associated protein kinase CAP1 regulates root hair growth in response to NH4+ treatment, with the cap1-1 mutant exhibiting hypersensitivity to NH4+ and elevated reactive oxygen species (ROS) levels. Based on our previous phosphoproteomic data, here we investigated the role of Respiratory Burst Oxidase Homolog D (AtRBOHD) in CAP1-mediated root hair growth under NH4+ treatment. Through yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BiFC), co-immunoprecipitation (Co-IP), and in vitro phosphorylation assays, we demonstrate that CAP1 physically interacts with and phosphorylates RBOHD, with Ser347 identified as a critical phosphorylation site in RBOHD that is required for their interaction. Genetic complementation assays revealed that expressing either wild-type RBOHD or its phospho-mimetic variant (RBOHDS347D) partially restored root hair growth in cap1-1 mutants while reducing ROS levels to those of the wild type under NH4+ treatment. Collectively, our findings establish a mechanistic model in which CAP1 phosphorylates RBOHD at Ser347 to regulate NH4+-dependent root hair growth by modulating ROS homeostasis.
Hong Yang, Lianlian Wang, Yichen Dong et al.· Plant Science· 0 citations
It is shown that the Arabidopsis NatA N-terminal-acetyltransferase complex acts as a leaf-intrinsic brake on these root-to-leaf systemic responses to ISR priming, enabling plants to sustain lifelong ISR priming without growth penalty.
Xiao-Jie Chen, Gu-Zi Chen, Yao Xu et al.· Proceedings of the National...· 0 citations
Root hairs are tubular protrusions of root epidermal cells that expand the root surface area to facilitate water and nutrient uptake. The target of rapamycin (TOR) kinase has been identified as a positive regulator of root hair elongation, and the RHD6-RSL4 bHLH transcriptional cascade is well established as a core module that governs root hair morphogenesis. However, whether TOR signaling acts upstream of the RHD6-RSL4 pathway and how glucose signals are integrated into this transcriptional regulatory network during root hair development remain incompletely understood. In this study, transcriptome profiling combined with pharmacological and genetic functional assays was performed to elucidate the TOR-mediated transcriptional regulatory pathway of root hair elongation in Arabidopsis. Chemical inhibition of TOR triggered genome-wide transcriptional reprogramming in seedling roots, including disruption of auxin and ethylene signal transduction and pronounced downregulation of hundreds of genes related to root hair development. Glucose-activated TOR signaling modulates the expression of root hair-specific (RHS) genes mainly through the core RHD6-RSL4 transcriptional cascade. The transcription of RSL1–RSL5 was strongly dependent on functional TOR activity, whereas RHD6 transcript abundance was specifically induced by glucose–TOR signaling under carbon-starvation recovery conditions. Genetic overexpression of either RHD6 or RSL4 partially rescued root hair elongation defects caused by TOR suppression, confirming that the RHD6-RSL4 cascade functions as a critical downstream transcriptional module of glucose–TOR signaling. Collectively, this work establishes a transcriptional framework in which glucose–TOR signals modulate root hair elongation via transcriptional activation of the master bHLH regulators RHD6 and RSL4.
Bing-Ru Wang, Jue Zhang, Wei Yan et al.· Plants· 0 citations
Phytosulfokine (PSK) is a crucial phytohormone that has been identified for over three decades; however, its transcriptional signaling pathway remains largely unexplored. Here, we disclose a PSK-triggered transcriptional signaling pathway that fine-tunes the tradeoff between growth and immunity in Arabidopsis thaliana. Through forward genetics, we identified the Growth Retardation and Autoimmunity 1 (GRA1) gene, which encodes tyrosylprotein sulfotransferase (TPST), a key enzyme essential for the biosynthesis of sulfated peptides. Notably, similar to the gra1 mutant, the PSK receptor double mutants pskr1 pskr2 also exhibit the gra1-like phenotype, characterized by growth retardation and autoimmunity. Exogenous PSK application rescued the growth defects in gra1 mutants, while overexpression of the PSK precursor gene PSK3 significantly enhanced plant growth. Integrated transcriptomic, genetic, and biochemical analyses demonstrated that PSK represses salicylic acid (SA)-dependent autoimmunity via the transcription factor CAMTA3 to promote plant growth. Mechanistically, PSK attenuates CAMTA3 phosphorylation, thereby enhancing CAMTA3 protein stability and facilitating its nuclear accumulation to constrain SA-mediated autoimmunity. CaM6 and CaM7, two calmodulins that interact with the PSK receptor PSKR1, directly bind to and stabilize CAMTA3. Ectopic expression of CAMTA3 triggers autoimmunity in the cam6 cam7 double mutants but enhances plant growth in wild-type plants, demonstrating that CaM6/7 are indispensable for CAMTA3-dependent growth promotion downstream of PSK signaling. In summary, this study uncovers a previously uncharacterized transcriptional regulatory pathway through which PSK orchestrates the balance between plant growth and immunity.
Penghong Zhang, Yujia Li, F. Yu et al.· Plant Communications· 0 citations
The pistil, a key female reproductive organ in flowering plants, plays a critical role in sexual reproduction. Although pistil function has been well studied in some species, the molecular mechanisms governing its development in rice (Oryza sativa) remain unclear. Here, we isolated and characterized a female-sterile rice mutant, Osdpms1, that exhibits pleiotropic reproductive defects, including greater stigma number and aberrant gametophyte development, while maintaining normal vegetative growth and male fertility. Using map-based cloning, genetic complementation, and CRISPR-Cas9 knockout experiments, we determined that LOC_Os07g03160 (named OsDPMS1), encoding a protein containing a WD40 repeat domain, is the causal gene underlying the mutant phenotype. OsDPMS1 was predominantly expressed during the flowering stage, and subcellular localization experiments revealed that OsDPMS1 localizes to both the nucleus and the cytoplasm. Using yeast two-hybrid, bimolecular fluorescence complementation, and GST-pulldown assays, we demonstrated that OsDPMS1 physically interacts with three components of the 26S proteasome pathway: OsUBQ, OsCDC48, and OsCDC48E. Furthermore, we showed that the female sterility of Osdpms1 can be efficiently maintained via seed production technology. When we combined Osdpms1 with male-sterile lines for hybrid seed production in a mixed planting manner, we achieved yield potentials comparable to those using conventional row-planting methods. Our findings establish OsDPMS1 as a critical regulator of pistil development and female fertility in rice and highlight its potential application in hybrid rice breeding programs.
