Nature Plants最新文献

Arabidopsis PHOSPHATE 1 (AtPHO1) and its closest homologue AtPHO1;H1 are phosphate transporters that load phosphate into the xylem vessel for root-to-shoot translocation. AtPHO1 and AtPHO1;H1 are prototypical members of the unique SPX–EXS family, whose structural and molecular mechanisms remain elusive. In this study, we determined the cryogenic electron microscopy structure of AtPHO1;H1 binding with inorganic phosphate (Pi) and inositol hexakisphosphate in a closed conformation. Further molecular dynamic simulation and AlphaFold prediction support an open conformation. AtPHO1;H1 forms a domain-swapped homodimer that involves both the transmembrane ERD1/XPR1/SYG1 (EXS) domain and the cytoplasmic SYG1/Pho81/XPR1 (SPX) domain. The EXS domain presented by the SPX–EXS family represents a novel protein fold, and an independent substrate transport pathway and substrate-binding site are present in each EXS domain. Two gating residues, Trp719 and Tyr610, are identified above the substrate-binding site to control opening and closing of the pathway. The SPX domain features positively charged patches and/or residues at the dimer interface to accommodate inositol hexakisphosphate molecules, whose binding mediates dimerization and enhances AtPHO1;H1 activity. In addition, a C-terminal tail is required for AtPHO1;H1 activity. On the basis of structural and functional analysis, a working model for Pi efflux mediated by AtPHO1;H1 and its homologues was postulated, suggesting a channel-like mechanism. This study not only reveals the molecular and regulatory mechanism underlying Pi transport mediated by the unique SPX–EXS family, but also provides potential for crop engineering to enhance phosphorus-use efficiency in sustainable agriculture.

Plants deploy cell-surface pattern recognition receptors (PRRs) and intracellular nucleotide-binding site–leucine-rich repeat receptors (NLRs) to recognize pathogens. However, how plant immune receptor repertoires evolve in responding to changed pathogen burdens remains elusive. Here we reveal the convergent reduction of NLR repertoires in plants with diverse special lifestyles/habitats (SLHs) encountering low pathogen burdens. Furthermore, a parallel but milder reduction of PRR genes in SLH species was observed. The reduction of PRR and NLR genes was attributed to both increased gene loss and decreased gene duplication. Notably, pronounced loss of immune receptors was associated with the complete absence of signalling components from the enhanced disease susceptibility 1 (EDS1) and the resistance to powdery mildew 8 (RPW8)-NLR (RNL) families. In addition, evolutionary pattern analysis suggested that the conserved toll/interleukin-1 receptor (TIR)-only proteins might function tightly with EDS1/RNL. Taken together, these results reveal the hierarchically adaptive evolution of the two-tiered immune receptor repertoires during plant adaptation to diverse SLHs.

Parthenocarpy is a pivotal trait that enhances the yield and quality of fruit crops by enabling the development of seedless fruits. Here we unveil a molecular framework for the regulation and domestication of parthenocarpy in cucumber (Cucumis sativus L.). We previously discovered a natural non-parthenocarpic mutant and demonstrated that the AP2-like transcription factor NON-PARTHENOCARPIC FRUIT 1 (NPF1) is a central regulator of parthenocarpy through activating YUC4 expression and promoting auxin biosynthesis in ovules. A Phe-to-Ser substitution at amino acid residue 7 results in a stable form of NPF1 that is localized in the nucleus. An A-to-G polymorphism (SNP-383) within an NPF1-binding site in the YUC4 promoter significantly enhances the activation of NPF1 towards YUC4, leading to an increased rate of parthenocarpy. Additionally, NPF1 influences bitterness by reducing cucurbitacin C biosynthesis through the suppression of Bt expression. Our results suggest a two-step evolutionary model for parthenocarpy and fruit bitterness during cucumber domestication.

Precise manipulation of genome structural variations holds great potential for plant trait improvement and biological research. Here we present a genome-editing approach, dual prime editing (DualPE), that efficiently facilitates precise deletion, replacement and inversion of large DNA fragments in plants. In our experiments, DualPE enabled the production of specific genomic deletions ranging from ~500 bp to 2 Mb in wheat protoplasts and plants. DualPE was effective in directly replacing wheat genomic fragments of up to 258 kb with desired sequences in the absence of donor DNA. Additionally, DualPE allowed precise DNA inversions of up to 205.4 kb in wheat plants with efficiencies of up to 51.5%. DualPE also successfully edited large DNA fragments in the dicots Nicotiana benthamiana and tomato, with editing efficiencies of up to 72.7%. DualPE thus provides a precise and efficient approach for large DNA sequence and chromosomal engineering, expanding the availability of precision genome-editing tools for crop improvement.

Hydrogen peroxide (H₂O₂) functions as a critical signalling molecule in controlling multiple biological processes. How H₂O₂ signalling integrates with other regulatory pathways such as epigenetic modification to coordinately regulate plant development remains elusive. Here we report that SlALKBH2, an m⁶A demethylase required for normal ripening of tomato fruit, is sensitive to oxidative modification by H₂O₂, which leads to the formation of homodimers mediated by intermolecular disulfide bonds, and Cys39 serves as a key site in this process. The oxidation of SlALKBH2 promotes protein stability and facilitates its function towards the target transcripts including the pivotal ripening gene SlDML2 encoding a DNA demethylase. Furthermore, we demonstrate that the thioredoxin reductase SlNTRC interacts with SlALKBH2 and catalyses its reduction, thereby modulating m⁶A levels and fruit ripening. Our study establishes a molecular link between H₂O₂ and m⁶A methylation and highlights the importance of redox regulation of m⁶A modifiers in controlling fruit ripening.